Voyager 1 observed changes in cosmic ray intensities on August 25, 2012 when it was 122 AU from the Sun, indicating it had entered a new region outside the heliosphere still dominated by the Sun's magnetic field. Energetic particles from inside the heliosphere disappeared, while intensities of low-energy galactic cosmic rays increased. Analysis of cosmic ray spectra revealed hydrogen and helium spectra peaking between 10-40 MeV/nucleon, consistent with abundances in the solar photosphere. This provides the first direct measurements of low-energy galactic cosmic rays outside of Earth's environment.
Search for the Exit: Voyager 1 at Heliosphere’s Border with the Galaxy.Carlos Bella
Voyager 1 has detected changes in energetic particle intensities that suggest it has reached the outer boundary of the heliosphere and entered interstellar space. Measurements show a sudden decrease in particles of solar origin by over 100 times on August 25, 2012, while galactic cosmic rays increased by 9.3% at the same time. This indicates Voyager 1 has reached a region dominated by interstellar plasma rather than heated solar plasma. The spacecraft is now detecting unexpected anisotropies in cosmic rays and temporary increases that may be associated with large solar storms, implying it is still within a transitional region to the local interstellar medium.
Search for the_exit_voyager1_at_heliosphere_border_with_the_galaxySérgio Sacani
Voyager 1 has detected changes in energetic particle intensities that suggest it has reached the outer boundary of the heliosphere and entered interstellar space. Measurements show a sudden decrease in particles of solar origin by over 100 times on August 25, 2012, while galactic cosmic rays increased by 9.3% at the same time. This indicates Voyager 1 has reached a region dominated by interstellar plasma rather than heated solar plasma. The spacecraft is now detecting unexpected anisotropies in cosmic rays and temporary increases that may be associated with large solar storms, implying it is still within a transitional region to the local interstellar medium.
This document discusses electromagnetic waves and Maxwell's equations. It provides an overview of key topics:
- Maxwell derived equations showing electric and magnetic fields form propagating waves at the speed of light.
- The electromagnetic spectrum ranges from radio to gamma rays. Waves are generated by oscillating electric fields creating magnetic fields and vice versa.
- Maxwell's equations precisely relate the electric and magnetic fields and how they vary over time. This allowed calculation of the waves' speed as the measured speed of light.
This document summarizes how diffraction occurs as a consequence of Faraday's law of induction. It describes how a linearly polarized electromagnetic wave incident on an opaque screen with a small aperture will develop both transverse and longitudinal magnetic field components after passing through the aperture. Specifically:
1) Applying Faraday's law to a semicircular loop near the aperture shows that the time derivative of the magnetic flux through the loop is non-zero, indicating a longitudinal magnetic field component.
2) The ratio of the longitudinal to transverse magnetic field is derived, showing this ratio is a measure of the diffraction angle of the wave.
3) It is concluded that the wave is diffracted and no longer a plane wave after passing through the
Discovery of superluminal velocities of X-rays and Bharat Radiation challengi...IOSR Journals
This document discusses the discovery of superluminal velocities of X-rays and Bharat radiation based on solar spectral evidence. The evidence challenges Einstein's assertion that nothing can travel faster than the speed of light. Solar spectra recorded in 2011 showed GOES X-rays arriving earlier than 13.5 nm emissions, which arrived earlier than 33.5 nm emissions, indicating the shorter wavelengths traveled faster. The author provides an explanation for how the emissions originated from the same excited atoms in solar flares, allowing a conclusion that the X-rays and 13.5 nm radiation traveled faster than the speed of light. This challenges the validity of Einstein's mass-energy equivalence formula E=mc2 for high-energy electromagnetic radiation like X-
This document provides an overview of electromagnetic waves and key concepts in physics including:
- James Clerk Maxwell showed that electric and magnetic fields can form propagating electromagnetic waves.
- Electromagnetic waves include visible light, ultraviolet rays, infrared rays, radio waves, x-rays and gamma rays.
- The speed of electromagnetic waves in a vacuum is a constant at approximately 3×10^8 m/s.
- Electromagnetic waves transport energy and the total energy density carried by a wave depends on the electric and magnetic field amplitudes.
1) James Clerk Maxwell formulated a theory unifying electricity and magnetism known as Maxwell's equations.
2) Maxwell's equations predicted that changing electric and magnetic fields would propagate as electromagnetic waves moving at the speed of light.
3) This theoretical prediction was later confirmed with the realization that visible light is a type of electromagnetic wave, providing strong evidence for the power and validity of Maxwell's theory.
Maxwell derived a set of equations that unified electricity, magnetism and light as manifestations of electromagnetic waves. His equations predicted that changes in electric and magnetic fields propagate as waves at the speed of light. This supported Maxwell's theory that light itself is an electromagnetic wave. The electromagnetic spectrum encompasses all possible frequencies of electromagnetic waves, from radio waves to gamma rays. Maxwell's equations form the basis for the modern understanding of electromagnetism and optics.
Search for the Exit: Voyager 1 at Heliosphere’s Border with the Galaxy.Carlos Bella
Voyager 1 has detected changes in energetic particle intensities that suggest it has reached the outer boundary of the heliosphere and entered interstellar space. Measurements show a sudden decrease in particles of solar origin by over 100 times on August 25, 2012, while galactic cosmic rays increased by 9.3% at the same time. This indicates Voyager 1 has reached a region dominated by interstellar plasma rather than heated solar plasma. The spacecraft is now detecting unexpected anisotropies in cosmic rays and temporary increases that may be associated with large solar storms, implying it is still within a transitional region to the local interstellar medium.
Search for the_exit_voyager1_at_heliosphere_border_with_the_galaxySérgio Sacani
Voyager 1 has detected changes in energetic particle intensities that suggest it has reached the outer boundary of the heliosphere and entered interstellar space. Measurements show a sudden decrease in particles of solar origin by over 100 times on August 25, 2012, while galactic cosmic rays increased by 9.3% at the same time. This indicates Voyager 1 has reached a region dominated by interstellar plasma rather than heated solar plasma. The spacecraft is now detecting unexpected anisotropies in cosmic rays and temporary increases that may be associated with large solar storms, implying it is still within a transitional region to the local interstellar medium.
This document discusses electromagnetic waves and Maxwell's equations. It provides an overview of key topics:
- Maxwell derived equations showing electric and magnetic fields form propagating waves at the speed of light.
- The electromagnetic spectrum ranges from radio to gamma rays. Waves are generated by oscillating electric fields creating magnetic fields and vice versa.
- Maxwell's equations precisely relate the electric and magnetic fields and how they vary over time. This allowed calculation of the waves' speed as the measured speed of light.
This document summarizes how diffraction occurs as a consequence of Faraday's law of induction. It describes how a linearly polarized electromagnetic wave incident on an opaque screen with a small aperture will develop both transverse and longitudinal magnetic field components after passing through the aperture. Specifically:
1) Applying Faraday's law to a semicircular loop near the aperture shows that the time derivative of the magnetic flux through the loop is non-zero, indicating a longitudinal magnetic field component.
2) The ratio of the longitudinal to transverse magnetic field is derived, showing this ratio is a measure of the diffraction angle of the wave.
3) It is concluded that the wave is diffracted and no longer a plane wave after passing through the
Discovery of superluminal velocities of X-rays and Bharat Radiation challengi...IOSR Journals
This document discusses the discovery of superluminal velocities of X-rays and Bharat radiation based on solar spectral evidence. The evidence challenges Einstein's assertion that nothing can travel faster than the speed of light. Solar spectra recorded in 2011 showed GOES X-rays arriving earlier than 13.5 nm emissions, which arrived earlier than 33.5 nm emissions, indicating the shorter wavelengths traveled faster. The author provides an explanation for how the emissions originated from the same excited atoms in solar flares, allowing a conclusion that the X-rays and 13.5 nm radiation traveled faster than the speed of light. This challenges the validity of Einstein's mass-energy equivalence formula E=mc2 for high-energy electromagnetic radiation like X-
This document provides an overview of electromagnetic waves and key concepts in physics including:
- James Clerk Maxwell showed that electric and magnetic fields can form propagating electromagnetic waves.
- Electromagnetic waves include visible light, ultraviolet rays, infrared rays, radio waves, x-rays and gamma rays.
- The speed of electromagnetic waves in a vacuum is a constant at approximately 3×10^8 m/s.
- Electromagnetic waves transport energy and the total energy density carried by a wave depends on the electric and magnetic field amplitudes.
1) James Clerk Maxwell formulated a theory unifying electricity and magnetism known as Maxwell's equations.
2) Maxwell's equations predicted that changing electric and magnetic fields would propagate as electromagnetic waves moving at the speed of light.
3) This theoretical prediction was later confirmed with the realization that visible light is a type of electromagnetic wave, providing strong evidence for the power and validity of Maxwell's theory.
Maxwell derived a set of equations that unified electricity, magnetism and light as manifestations of electromagnetic waves. His equations predicted that changes in electric and magnetic fields propagate as waves at the speed of light. This supported Maxwell's theory that light itself is an electromagnetic wave. The electromagnetic spectrum encompasses all possible frequencies of electromagnetic waves, from radio waves to gamma rays. Maxwell's equations form the basis for the modern understanding of electromagnetism and optics.
The document discusses electromagnetic waves and their properties. Some key points:
1) Electromagnetic waves consist of oscillating electric and magnetic fields perpendicular to each other and perpendicular to the direction of wave propagation.
2) Both the electric and magnetic fields of an electromagnetic wave are transverse to the direction of wave propagation.
3) Electromagnetic waves include radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. They differ in wavelength and frequency.
1) The document discusses several topics in quantum mechanics including Planck's law, Wien's law, Rayleigh-Jeans law, Compton scattering, the Compton effect, de Broglie's hypothesis of matter waves, and the Davisson-Germer experiment.
2) It explains that Compton scattering results in a shift in wavelength when X-rays interact with electrons. Compton treated this as particle collision between photons and electrons.
3) The Davisson-Germer experiment in 1927 provided the first evidence of matter waves by observing interference patterns when electrons were diffracted by a nickel crystal, supporting de Broglie's hypothesis that particles can behave as waves.
- The document discusses transverse and longitudinal waves. Transverse waves have a disturbance perpendicular to the direction of propagation, while longitudinal waves have a disturbance parallel to the direction of propagation.
- It provides examples of different types of waves - ocean water waves are a combination of transverse and longitudinal waves, while waves on guitar strings are transverse. Sound waves in air and water are longitudinal.
- Differentiating between longitudinal and transverse waves is important because the energy and motion propagate in different directions for each type of wave. This affects how the waves behave and transfer energy.
Pieter Zeeman was a Dutch physicist who shared the 1902 Nobel Prize in Physics with Hendrik Lorentz for his discovery of the Zeeman effect in 1896. The Zeeman effect is the splitting of spectral lines into multiple components when in the presence of a magnetic field. Zeeman observed that each emission line from a light source split into several lines when under the influence of a magnetic field. This splitting, known as the Zeeman effect, demonstrated that atomic energy levels are affected by magnetic fields.
This document provides information about quantum mechanics concepts such as:
1. The origin of spectral lines from hydrogen atoms and the Rydberg formula for calculating wavelengths.
2. De Broglie's hypothesis that particles have an associated wavelength and the formula for calculating this wavelength.
3. Davisson and Germer's experiment in 1927 which provided evidence for the wave nature of electrons by observing diffraction patterns when electrons were fired at a nickel crystal.
In wireless communication, we frequently use an electromagnetic wave. In this presentation, we can study wave equation, reflection, plane wave, and transmission line.
This document discusses MATLAB simulations of electromagnetic wave propagation characteristics in water and oil. The simulations show that in water (a conductive medium), the electric and magnetic fields are out of phase and their amplitudes are continuously attenuated during propagation. But in oil (a non-conductive medium), the electric and magnetic fields remain in phase and their amplitudes remain unchanged. The simulations provide insights into how electromagnetic waves can be used to measure oil spill thickness in water.
This document provides an overview of geometric optics and the behavior of light. It discusses three key topics:
1. The ray model of light, where light travels in straight lines called rays. Light can travel directly, through media, or after reflecting.
2. The law of reflection, which states that the angle of incidence is equal to the angle of reflection. Reflection occurs from smooth surfaces, while rough surfaces scatter light in many directions.
3. Geometric optics, which describes light using geometry and models its interactions with surfaces much larger than its wavelength as rays reflecting and refracting according to specific laws.
The document discusses the wave-particle duality of light and electrons. It describes how Max Planck proposed that electromagnetic radiation was quantized into discrete packets of energy called quanta or photons. Later, Albert Einstein applied this idea and suggested that light consists of quantized packets or photons. The document also discusses how Louis de Broglie applied wave-particle duality to electrons in 1924, showing that electrons can exhibit wave properties. This led to the development of quantum mechanics and the modern quantum mechanical model of the atom, which uses orbitals and quantum numbers to describe where electrons are likely to be found.
1) The document discusses concepts related to radiation heat transfer including radiative properties like reflectivity, transmissivity, and emissivity.
2) It describes how radiation shields can be used to reduce radiation heat transfer between surfaces by increasing the resistance to radiation flow through multiple reflections.
3) An example is given showing the calculation of radiation heat transfer rate between two parallel plates separated by an aluminum radiation shield, and how the rate is reduced compared to the case without the shield.
X raying the ejecta of supernova 1987 aSérgio Sacani
This study analyzed observations of Supernova 1987A (SN 1987A) from 1994 to 2009 using the Hubble Space Telescope. [1] From 1994 to 2001, the brightness of the ejecta faded as expected due to radioactive decay. [2] After 2001, the brightness began increasing, reaching over twice the 2001 level by 2009. [3] This study finds that the increase is caused by X-rays from the collision between the ejecta and surrounding circumstellar ring, which deposits heat in the ejecta and powers its increased brightness.
This document discusses polarization of antennas and polarization matching between antennas and electromagnetic waves. It can be summarized as:
1) The polarization of an antenna is the polarization of the wave it radiates, which is generally directionally dependent and can be elliptical, linear, or circular.
2) The vector effective length of an antenna relates the electric field it radiates to the input current and is usually a complex quantity.
3) For maximum power transfer between an antenna and an electromagnetic wave during reception, their polarizations must match, which can be quantified as polarization efficiency or polarization loss factor.
B.Tech sem I Engineering Physics U-IV Chapter 1-ATOMIC PHYSICSAbhi Hirpara
Atomic physics describes phenomena at the scale of atoms and subatomic particles. It emerged in the early 20th century to address limitations in classical physics' ability to describe certain phenomena. Quantum physics recognizes that there is less difference between waves and particles than previously thought. It is probabilistic and counterintuitive, describing particles that can behave as waves and vice versa. Quantum physics underlies our understanding of atomic and subatomic systems and is crucial to fields like chemistry, materials science, and astrophysics. Planck's quantum hypothesis proposed that atoms can only absorb or emit energy in discrete quanta, initiating the development of quantum theory. Einstein later theorized that electromagnetic radiation consists of discrete photon particles, helping explain the photoelectric effect.
1. Maxwell's equations predict that electromagnetic energy propagates away from time-varying sources in the form of waves.
2. The document derives the electromagnetic wave equation and describes its solution for uniform plane waves in various media.
3. Key wave properties like velocity, wavelength, frequency and attenuation are determined by examining solutions to the wave equations for the electric and magnetic fields.
Maxwell's equations describe the relationships between electric and magnetic fields and their sources. They show that changing electric fields produce magnetic fields and changing magnetic fields produce electric fields. This leads to the prediction that electric and magnetic fields can propagate as electromagnetic waves moving at the speed of light. The document provides examples of applying Maxwell's equations to derive the speed of light and describe propagating and standing electromagnetic waves. It also discusses the energy, momentum, and Poynting vector associated with electromagnetic waves.
Microwaves are electromagnetic waves with wavelengths between 1 mm and 1 m, or frequencies between 300 MHz and 300 GHz. They were first theorized by James Clerk Maxwell in 1864. Later, scientists like Heinrich Hertz and Albert Hull helped develop practical applications of microwaves such as radar and microwave ovens. Today, microwaves are used widely in technologies like GPS and in household appliances like microwave ovens, which use a magnetron to generate microwave radiation and heat food efficiently.
This document provides an overview of chapter 22 on electromagnetic induction. It discusses key concepts such as magnetic flux, Faraday's law of induction, Lenz's law, and applications including electric generators. The chapter covers how changing magnetic fields can induce emfs and currents in conductors based on Faraday's law. Lenz's law describes how the direction of induced currents will oppose the change that created them. Applications discussed include the reproduction of sound and electric generators.
The Michelson-Morley experiment was conducted between 1887 and 1926 using increasingly precise interferometers to attempt to detect the hypothesized luminiferous ether and measure the speed of Earth through it. Michelson and Morley's 1887 experiment at Case Western Reserve University used an 11 meter interferometer and found no detectable fringe shift, contrary to predictions. Subsequent repeated experiments by multiple observers using improved designs up to 32 meters also found no detectable fringe shift, establishing that the luminiferous ether hypothesis was invalid and that the speed of light appears constant regardless of the motion of the light source. This result was one of the important experimental evidences leading to the development of special relativity.
Magnetic field observations_as_voyager1_entered_the_heliosheath_depletion_regionSérgio Sacani
1) Voyager 1 encountered an unexpected region in 2012 between 120-122 AU from the sun, entering it five times between days 210-238 based on magnetic field measurements.
2) When it entered this region, called the heliosheath depletion region (HDR), the magnetic field strength increased from around 0.2 nT to 0.4 nT and remained high, while energetic particle counts dropped significantly.
3) The direction of the magnetic field did not change significantly during the boundary crossings, indicating Voyager 1 likely did not cross the heliopause but remained in the heliosheath.
1) Global climate models that include sophisticated cloud schemes show that tidally locked planets can develop thick water clouds near the substellar point due to strong convection. These clouds greatly increase the planetary albedo and stabilize temperatures, allowing habitability at twice the stellar flux previously thought possible.
2) The cloud feedback is stabilizing, as higher stellar flux produces stronger convection and higher albedos. Substellar clouds can block outgoing radiation, reducing the day-night temperature contrast.
3) Non-tidally locked planets do not experience this stabilizing cloud feedback, as clouds only form over parts of the tropics and mid-latitudes. Their albedo decreases with increasing stellar flux, producing a destabil
Hubble Space Telescope observations of the globular cluster NGC 6752 reveal a broadened and asymmetric main sequence, indicative of a large binary population. Artificial star experiments show that photometric errors and chance star superpositions alone cannot account for the observed broadening. A Monte Carlo technique is used to estimate the binary fraction, which is likely 15-38% in the inner core but less than 16% beyond that radius. The discovery of a significant main-sequence binary population provides constraints on the dynamical evolution and stellar populations of globular clusters.
The document discusses electromagnetic waves and their properties. Some key points:
1) Electromagnetic waves consist of oscillating electric and magnetic fields perpendicular to each other and perpendicular to the direction of wave propagation.
2) Both the electric and magnetic fields of an electromagnetic wave are transverse to the direction of wave propagation.
3) Electromagnetic waves include radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. They differ in wavelength and frequency.
1) The document discusses several topics in quantum mechanics including Planck's law, Wien's law, Rayleigh-Jeans law, Compton scattering, the Compton effect, de Broglie's hypothesis of matter waves, and the Davisson-Germer experiment.
2) It explains that Compton scattering results in a shift in wavelength when X-rays interact with electrons. Compton treated this as particle collision between photons and electrons.
3) The Davisson-Germer experiment in 1927 provided the first evidence of matter waves by observing interference patterns when electrons were diffracted by a nickel crystal, supporting de Broglie's hypothesis that particles can behave as waves.
- The document discusses transverse and longitudinal waves. Transverse waves have a disturbance perpendicular to the direction of propagation, while longitudinal waves have a disturbance parallel to the direction of propagation.
- It provides examples of different types of waves - ocean water waves are a combination of transverse and longitudinal waves, while waves on guitar strings are transverse. Sound waves in air and water are longitudinal.
- Differentiating between longitudinal and transverse waves is important because the energy and motion propagate in different directions for each type of wave. This affects how the waves behave and transfer energy.
Pieter Zeeman was a Dutch physicist who shared the 1902 Nobel Prize in Physics with Hendrik Lorentz for his discovery of the Zeeman effect in 1896. The Zeeman effect is the splitting of spectral lines into multiple components when in the presence of a magnetic field. Zeeman observed that each emission line from a light source split into several lines when under the influence of a magnetic field. This splitting, known as the Zeeman effect, demonstrated that atomic energy levels are affected by magnetic fields.
This document provides information about quantum mechanics concepts such as:
1. The origin of spectral lines from hydrogen atoms and the Rydberg formula for calculating wavelengths.
2. De Broglie's hypothesis that particles have an associated wavelength and the formula for calculating this wavelength.
3. Davisson and Germer's experiment in 1927 which provided evidence for the wave nature of electrons by observing diffraction patterns when electrons were fired at a nickel crystal.
In wireless communication, we frequently use an electromagnetic wave. In this presentation, we can study wave equation, reflection, plane wave, and transmission line.
This document discusses MATLAB simulations of electromagnetic wave propagation characteristics in water and oil. The simulations show that in water (a conductive medium), the electric and magnetic fields are out of phase and their amplitudes are continuously attenuated during propagation. But in oil (a non-conductive medium), the electric and magnetic fields remain in phase and their amplitudes remain unchanged. The simulations provide insights into how electromagnetic waves can be used to measure oil spill thickness in water.
This document provides an overview of geometric optics and the behavior of light. It discusses three key topics:
1. The ray model of light, where light travels in straight lines called rays. Light can travel directly, through media, or after reflecting.
2. The law of reflection, which states that the angle of incidence is equal to the angle of reflection. Reflection occurs from smooth surfaces, while rough surfaces scatter light in many directions.
3. Geometric optics, which describes light using geometry and models its interactions with surfaces much larger than its wavelength as rays reflecting and refracting according to specific laws.
The document discusses the wave-particle duality of light and electrons. It describes how Max Planck proposed that electromagnetic radiation was quantized into discrete packets of energy called quanta or photons. Later, Albert Einstein applied this idea and suggested that light consists of quantized packets or photons. The document also discusses how Louis de Broglie applied wave-particle duality to electrons in 1924, showing that electrons can exhibit wave properties. This led to the development of quantum mechanics and the modern quantum mechanical model of the atom, which uses orbitals and quantum numbers to describe where electrons are likely to be found.
1) The document discusses concepts related to radiation heat transfer including radiative properties like reflectivity, transmissivity, and emissivity.
2) It describes how radiation shields can be used to reduce radiation heat transfer between surfaces by increasing the resistance to radiation flow through multiple reflections.
3) An example is given showing the calculation of radiation heat transfer rate between two parallel plates separated by an aluminum radiation shield, and how the rate is reduced compared to the case without the shield.
X raying the ejecta of supernova 1987 aSérgio Sacani
This study analyzed observations of Supernova 1987A (SN 1987A) from 1994 to 2009 using the Hubble Space Telescope. [1] From 1994 to 2001, the brightness of the ejecta faded as expected due to radioactive decay. [2] After 2001, the brightness began increasing, reaching over twice the 2001 level by 2009. [3] This study finds that the increase is caused by X-rays from the collision between the ejecta and surrounding circumstellar ring, which deposits heat in the ejecta and powers its increased brightness.
This document discusses polarization of antennas and polarization matching between antennas and electromagnetic waves. It can be summarized as:
1) The polarization of an antenna is the polarization of the wave it radiates, which is generally directionally dependent and can be elliptical, linear, or circular.
2) The vector effective length of an antenna relates the electric field it radiates to the input current and is usually a complex quantity.
3) For maximum power transfer between an antenna and an electromagnetic wave during reception, their polarizations must match, which can be quantified as polarization efficiency or polarization loss factor.
B.Tech sem I Engineering Physics U-IV Chapter 1-ATOMIC PHYSICSAbhi Hirpara
Atomic physics describes phenomena at the scale of atoms and subatomic particles. It emerged in the early 20th century to address limitations in classical physics' ability to describe certain phenomena. Quantum physics recognizes that there is less difference between waves and particles than previously thought. It is probabilistic and counterintuitive, describing particles that can behave as waves and vice versa. Quantum physics underlies our understanding of atomic and subatomic systems and is crucial to fields like chemistry, materials science, and astrophysics. Planck's quantum hypothesis proposed that atoms can only absorb or emit energy in discrete quanta, initiating the development of quantum theory. Einstein later theorized that electromagnetic radiation consists of discrete photon particles, helping explain the photoelectric effect.
1. Maxwell's equations predict that electromagnetic energy propagates away from time-varying sources in the form of waves.
2. The document derives the electromagnetic wave equation and describes its solution for uniform plane waves in various media.
3. Key wave properties like velocity, wavelength, frequency and attenuation are determined by examining solutions to the wave equations for the electric and magnetic fields.
Maxwell's equations describe the relationships between electric and magnetic fields and their sources. They show that changing electric fields produce magnetic fields and changing magnetic fields produce electric fields. This leads to the prediction that electric and magnetic fields can propagate as electromagnetic waves moving at the speed of light. The document provides examples of applying Maxwell's equations to derive the speed of light and describe propagating and standing electromagnetic waves. It also discusses the energy, momentum, and Poynting vector associated with electromagnetic waves.
Microwaves are electromagnetic waves with wavelengths between 1 mm and 1 m, or frequencies between 300 MHz and 300 GHz. They were first theorized by James Clerk Maxwell in 1864. Later, scientists like Heinrich Hertz and Albert Hull helped develop practical applications of microwaves such as radar and microwave ovens. Today, microwaves are used widely in technologies like GPS and in household appliances like microwave ovens, which use a magnetron to generate microwave radiation and heat food efficiently.
This document provides an overview of chapter 22 on electromagnetic induction. It discusses key concepts such as magnetic flux, Faraday's law of induction, Lenz's law, and applications including electric generators. The chapter covers how changing magnetic fields can induce emfs and currents in conductors based on Faraday's law. Lenz's law describes how the direction of induced currents will oppose the change that created them. Applications discussed include the reproduction of sound and electric generators.
The Michelson-Morley experiment was conducted between 1887 and 1926 using increasingly precise interferometers to attempt to detect the hypothesized luminiferous ether and measure the speed of Earth through it. Michelson and Morley's 1887 experiment at Case Western Reserve University used an 11 meter interferometer and found no detectable fringe shift, contrary to predictions. Subsequent repeated experiments by multiple observers using improved designs up to 32 meters also found no detectable fringe shift, establishing that the luminiferous ether hypothesis was invalid and that the speed of light appears constant regardless of the motion of the light source. This result was one of the important experimental evidences leading to the development of special relativity.
Magnetic field observations_as_voyager1_entered_the_heliosheath_depletion_regionSérgio Sacani
1) Voyager 1 encountered an unexpected region in 2012 between 120-122 AU from the sun, entering it five times between days 210-238 based on magnetic field measurements.
2) When it entered this region, called the heliosheath depletion region (HDR), the magnetic field strength increased from around 0.2 nT to 0.4 nT and remained high, while energetic particle counts dropped significantly.
3) The direction of the magnetic field did not change significantly during the boundary crossings, indicating Voyager 1 likely did not cross the heliopause but remained in the heliosheath.
1) Global climate models that include sophisticated cloud schemes show that tidally locked planets can develop thick water clouds near the substellar point due to strong convection. These clouds greatly increase the planetary albedo and stabilize temperatures, allowing habitability at twice the stellar flux previously thought possible.
2) The cloud feedback is stabilizing, as higher stellar flux produces stronger convection and higher albedos. Substellar clouds can block outgoing radiation, reducing the day-night temperature contrast.
3) Non-tidally locked planets do not experience this stabilizing cloud feedback, as clouds only form over parts of the tropics and mid-latitudes. Their albedo decreases with increasing stellar flux, producing a destabil
Hubble Space Telescope observations of the globular cluster NGC 6752 reveal a broadened and asymmetric main sequence, indicative of a large binary population. Artificial star experiments show that photometric errors and chance star superpositions alone cannot account for the observed broadening. A Monte Carlo technique is used to estimate the binary fraction, which is likely 15-38% in the inner core but less than 16% beyond that radius. The discovery of a significant main-sequence binary population provides constraints on the dynamical evolution and stellar populations of globular clusters.
Global collapse of_molecular_clouds_as_a_formation_mechanism_for_the_most_mas...Sérgio Sacani
This document summarizes observations of the massive star-forming cloud SDC335 made using Spitzer, Herschel, Mopra, and ALMA. It finds that SDC335 contains over 5500 solar masses of gas distributed in a network of filaments that converge on a central hub region. ALMA observations reveal two massive cores within this hub region, the most massive of which contains over 500 solar masses of gas. Kinematic analysis of molecular line data from Mopra and ALMA indicates that the cloud is undergoing global collapse, with infalling gas bringing additional material at a rate of over 2.5 solar masses per year to the central region, which could double its mass within the next few million years and allow
Herschel galactic plane_survey_the_global_distribution_of_ism_gas_componnentSérgio Sacani
This document summarizes a study using Herschel observations of the [C ii] 158μm line to analyze the distribution of different gas components in the Milky Way galaxy. The observations provide high-resolution maps of [C ii] emission across the Galactic plane. By comparing these maps to observations of HI, CO, and other tracers, the study finds that [C ii] emission is associated with spiral arms between 4-10 kpc from the Galactic center. It estimates that [C ii] traces dense photon-dominated regions (47%), CO-dark H2 gas (28%), cold atomic gas (21%), and ionized gas (4%). The study also analyzes the distribution of cold neutral medium versus
This document summarizes the analysis of periodic variable stars in the open cluster NGC 3766 based on a 7-year monitoring campaign. The authors detected a new class of 36 variable stars located between the instability strips for slowly pulsating B stars and delta Scuti stars, where no variability was previously predicted. The majority of these new variables have periods between 0.1-0.7 days and amplitudes of 1-4 millimagnitudes. The properties of this new class are discussed and the authors argue they are likely pulsating variables sustained by stellar rotation. Additionally, the authors identify other periodic variables such as eclipsing binaries, slowly pulsating B stars, delta Scuti stars, and gamma Doradus candidates.
The deep blue_color_of_hd189733b_albedo_measurements_with_hst_stis_at_visible...Sérgio Sacani
The document summarizes a study that measured the geometric albedo of the exoplanet HD 189733b across visible wavelengths using Hubble Space Telescope observations. It found an albedo of 0.40 ± 0.12 at 290-450 nm that decreased to below 0.12 at 450-570 nm, suggesting optically thick clouds reflecting light at shorter wavelengths and sodium absorption suppressing reflection beyond 450 nm. This wavelength-dependent albedo implies HD 189733b would appear deep blue in color at visible wavelengths.
A population of_fast_radio_bursts_ar_cosmological_distancesSérgio Sacani
1) Four fast radio bursts (FRBs) lasting only a few milliseconds were detected in a radio survey of the high Galactic latitude sky.
2) The bursts' properties indicate they are of celestial rather than terrestrial origin and likely originate from cosmological distances of 0.5 to 3 billion light years.
3) No coincident x-ray or gamma-ray signals were found associated with the bursts. Characterizing the population of FRBs could help determine the baryonic content of the universe.
Detection of the_central_star_of_the_planetary_nebula_ngc_6302Sérgio Sacani
The document summarizes the detection of the central star of the planetary nebula NGC 6302 using new observations from the Hubble Space Telescope's Wide Field Camera 3. Key points:
1) The central star is directly detected for the first time at the center of the nebula, confirming its location but not at the center of the inner dust torus.
2) Photometry of the central star yields a reddening value of c=3.1, corresponding to AV=6.6 magnitudes of extinction, mostly from circumstellar dust.
3) Estimates of the stellar temperature, luminosity, and distance suggest a fairly massive central star of around 0.64 solar masses that is evolving rapidly and fading over time
This document summarizes a 1.3 mm continuum survey of protoplanetary disks in the 2-3 Myr old IC348 star cluster using the Submillimeter Array. 10 disks out of 85 young stars were detected with masses ranging from 2-6 Jupiter masses. This distribution is shifted to lower masses by a factor of 20 compared to younger regions like Taurus and Ophiuchus. The results reveal a rapid decline in the number of small dust grains in disks after 1 Myr, likely due to grain growth. The few detected disks may be the best candidates in IC348 to study planet formation.
This document summarizes the results of an MHD simulation coupled with a radiation transport model to simulate X-ray spectra from an accreting black hole. Key points:
- For the first time, the simulation is able to reproduce the main components seen in observed X-ray spectra, including a thermal peak, power-law tail, reflection hump, and iron line, by varying only the mass accretion rate.
- The temperature in the corona varies from 10 keV near the disk to over 100 keV in low-density regions, producing the hard X-ray emission through inverse-Compton scattering.
- Even as the disk's reflection edge varies from the horizon out to 6 gravitational radii with decreasing accretion
Insects live fascinating lives and play important roles in ecosystems. Marco Belzoni gave a presentation in 2010 about the magical world of insects, sharing photos and music to educate others. While the presentation materials were copyrighted, insects deserve our appreciation for their amazing diversity and contributions to the natural world.
Too much pasta_for_pulsars_to_spin_downSérgio Sacani
This document summarizes a study investigating why no isolated X-ray pulsars have been observed with spin periods longer than 12 seconds. The researchers suggest this is due to a highly resistive layer in the inner crust of neutron stars, which is expected to be in a state called "nuclear pasta". Nuclear pasta has an irregular structure that increases electrical resistivity, limiting the spin-down of pulsars. Modeling the long-term magnetic field evolution incorporating a resistive nuclear pasta layer successfully reproduced the observed 12 second period limit. The results provide the first potential observational evidence for the existence of nuclear pasta in neutron star crusts.
The sombrero galaxy_modelling_the_dust_contentSérgio Sacani
The document repeatedly lists the reference "1995A&A...303..673E" 18 times without providing any other context or information. It is unclear what the document is about based on the limited reference listing provided.
Dust in the_polar_region_as_a_major_contributor_to_the_infrared_emission_of_a...Sérgio Sacani
The mid-infrared emission of the active galactic nucleus NGC 3783 was observed using interferometry over multiple epochs, providing dense coverage of position angles and baselines. The emission was found to be strongly elongated along a position angle of -52 degrees, closely aligned with the polar axis orientation of -45 degrees. The half-light radii were measured to be 20.0 mas by 6.7 mas, corresponding to an axis ratio of 3:1. This implies that 60-90% of the 8-13 micron emission is from the polar-elongated component. The observations support a scenario where the majority of mid-infrared emission in Seyfert galaxies originates from a dusty wind in the polar region,
A dynamically packed_planetary _system_around_gj667_c_with_three_superearths_...Sérgio Sacani
This document summarizes the discovery of six potentially habitable super-Earth planets orbiting the red dwarf star GJ 667C. Analyzing new Doppler measurements from HARPS and previous data from other spectrographs, the authors detect six planetary candidates with orbital periods of 7, 28, 92, 62, 39, and 260 days. They validate the signals against stellar activity and find the system could be dynamically stable. Three or four of the planets may be located within the star's habitable zone where liquid water could exist, making this one of the first exoplanetary systems discovered with multiple Earth-sized planets in the habitable zone of an M-dwarf star.
The document lists various natural elements such as species, ecosystems, habitats, soils, clouds, lakes, rivers, mountains, humans, insects, mammals, oceans, birds, fishes, worms, plants, and flowers in repetitive phrases without any connecting context.
Insects have developed various ways to communicate, including through sight, smell, touch, dancing, and sound. They communicate to find food, defend their nests, and find mates. Sight is used by dragonflies and fireflies to recognize each other. Smell involves glands producing odors detected by antennae. Touch involves transferring chemicals through antennae contact. Bees communicate through dancing. Sound methods are used by cicadas, crickets, and mosquitoes.
This document discusses insect migration in three paragraphs or less:
Insects migrate to escape unfavorable conditions like temperature extremes, lack of food or water, or overcrowding. Common migratory insects include monarch butterflies, dragonflies, locusts, and aphids. Migration can occur over long distances of hundreds to thousands of kilometers and is often driven by seasonal changes and availability of resources across environments. Remote sensing technologies like radar are useful for monitoring large-scale insect migrations.
This document summarizes different types of communication used by insects, including visual, chemical, tactile, and acoustic communication. It discusses how insects communicate through color patterns, pheromones, touch, dance, sounds, and vibrations to recognize others of their species, find mates, locate food, warn of danger, and more. The key forms of communication are chemical signals like pheromones that convey information between individuals of the same species, and visual signals from patterns, flashes of light, or dances that help with tasks like attracting mates or locating food sources. Insects rely on these innate communication abilities to survive and thrive in their environments.
1. On August 25, 2012 at a distance of 121.7 AU from the Sun, Voyager 1 observed sudden and unprecedented changes in anomalous cosmic rays (ACR) and galactic cosmic rays (GCR).
2. Within a few days, the intensity of ACR protons and helium nuclei between 1.9-2.7 MeV decreased by over 99%, while the intensity of GCR protons, helium, and electrons increased by factors of 1.5 to 2.
3. These abrupt changes indicate that Voyager 1 crossed a well-defined boundary at this time, possibly related to the heliopause, that acts as an effective barrier to ACR but allows increased GCR flux.
Resolved imaging confirms a radiation belt around an ultracool dwarfSérgio Sacani
Radiation belts are present in all large-scale Solar System planetary
30 magnetospheres: Earth, Jupiter, Saturn, Uranus, and Neptune1. These persistent
31 equatorial zones of relativistic particles up to tens of MeV in energy can extend farther
32 than 10 times the planet’s radius, emit gradually varying radio emissions2–4 and impact
33 the surface chemistry of close-in moons5. Recent observations demonstrate that very low
34 mass stars and brown dwarfs, collectively known as ultracool dwarfs, can produce planet35
like radio emissions such as periodically bursting aurorae6–8 from large-scale
36 magnetospheric currents9–11. They also exhibit slowly varying quiescent radio
37 emissions7,12,13 hypothesized to trace low-level coronal flaring14,15 despite departing from
38 empirical multi-wavelength flare relationships8,15. Here we present high resolution
39 imaging of the ultracool dwarf LSR J1835+3259 at 8.4 GHz demonstrating that its
40 quiescent radio emission is spatially resolved and traces a double-lobed and axisymmetric
41 structure similar in morphology to the Jovian radiation belts. Up to 18 ultracool dwarf
42 radii separate the two lobes, which are stably present in three observations spanning
43 more than one year. For plasma confined by the magnetic dipole of LSR J1835+3259, we
44 estimate 15 MeV electron energies consistent with Jupiter’s radiation belts4. Our results
45 confirm recent predictions of radiation belts at both ends of the stellar mass sequence8,16–
46 19 and support broader re-examination of rotating magnetic dipoles in producing non47
thermal quiescent radio emissions from brown dwarfs7, fully convective M dwarfs20, and
4
Magnetic fields and relativistic electrons fill entire galaxy clusterSérgio Sacani
- The authors analyzed deep LOFAR radio observations of the galaxy cluster Abell 2255, detecting radio synchrotron emission distributed over an unprecedented scale of at least 5 megaparsecs, well beyond the cluster outskirts.
- This pervasive radio emission indicates that shocks and turbulence efficiently transfer kinetic energy into relativistic particles and magnetic fields throughout the cluster, including the periphery.
- The strength of the emission requires magnetic field energy densities at least 100 times higher than expected from simple compression of primordial fields, suggesting efficient dynamo action even in the cluster outskirts.
A luminous X-ray outburst from an intermediatemass black hole in an off-centr...Sérgio Sacani
A unique signature for the presence of massive black holes in
very dense stellar regions is occasional giant-amplitude outbursts
of multi-wavelength radiation from tidal disruption and
subsequent accretion of stars that make a close approach to
the black holes1
. Previous strong tidal disruption event (TDE)
candidates were all associated with the centres of largely
isolated galaxies2–6. Here, we report the discovery of a luminous
X-ray outburst from a massive star cluster at a projected
distance of 12.5 kpc from the centre of a large lenticular galaxy.
The luminosity peaked at ~1043 erg s−1
and decayed systematically
over 10 years, approximately following a trend
that supports the identification of the event as a TDE. The
X-ray spectra were all very soft, with emission confined to be
≲3.0 keV, and could be described with a standard thermal disk.
The disk cooled significantly as the luminosity decreased—a
key thermal-state signature often observed in accreting stellar-mass
black holes. This thermal-state signature, coupled
with very high luminosities, ultrasoft X-ray spectra and the
characteristic power-law evolution of the light curve, provides
strong evidence that the source contains an intermediatemass
black hole with a mass tens of thousand times that of
the solar mass. This event demonstrates that one of the most
effective means of detecting intermediate-mass black holes is
through X-ray flares from TDEs in star clusters.
In your previous class you have already studies about the structure of an atom but some of the exception you can learn here in this chapter how the structure of an atom is fully defined
1) Experiments with cathode ray tubes led to the discovery of the electron as a negatively charged fundamental particle.
2) Further experiments showed that atoms are mostly empty space and contain a small, dense nucleus made up of protons and neutrons, around which electrons orbit.
3) The photoelectric effect showed that light behaves as a particle (photon) rather than just a wave, transferring its energy in discrete quantized amounts to electrons and ejecting them from metal surfaces.
1. The document discusses the discovery of the electron through cathode ray experiments and the determination of the charge to mass ratio of electrons.
2. Rutherford's alpha particle scattering experiments showed that the atom has a small, dense nucleus containing positive charge and mass, surrounded by electrons. This led to the development of the Rutherford model of the atom.
3. The document also discusses the discovery of protons and neutrons, atomic number and mass number, isotopes, drawbacks of the Rutherford model, wave-particle duality of light, and Planck's quantum theory.
Todo mundo sabe que os raios produzidos pela Estrela da Morte em Guerra nas Estrelas não pode existir na vida real, porém no universo existem fenômenos que as vezes conseguem superar até a mais surpreendente ficção.
A galáxia Pictor A, é um desses objetos que possuem fenômenos tão espetaculares quanto aqueles exibidos no cinema. Essa galáxia localiza-se a cerca de 500 milhões de anos-luz da Terra e possui um buraco negro supermassivo no seu centro. Uma grande quantidade de energia gravitacional é lançada, à medida que o material cai em direção ao horizonte de eventos, o ponto sem volta ao redor do buraco negro. Essa energia produz um enorme jato de partículas que viajam a uma velocidade próxima da velocidade da luz no espaço intergaláctico, chamado de jato relativístico.
Para obter imagens desse jato, os cientistas usaram o Observatório de Raios-X Chandra, da NASA várias vezes durante 15 anos. Os dados do Chandra, apresentados em azul nas imagens, foram combinados com os dados obtidos em ondas de rádio a partir do Australia Telescope Compact Array, e são aparesentados em vermelho nas imagens.
This document discusses various plasma diagnostic techniques including optical emission spectroscopy, laser-induced fluorescence, and absorption spectroscopy. Instrumentation for plasma diagnostics typically includes a light source, light guide, spectrometer, and detector. Optical emission spectroscopy analyzes light emitted from plasma and can be used to determine electron temperature and density. Laser-induced fluorescence excites plasma species with a laser and analyzes spontaneous emission. Absorption spectroscopy measures light absorption through plasma to determine species concentrations. Hydrogen Balmer lines are commonly used for density measurements as hydrogen can be added without disturbing the plasma.
CBSE Class 11 Chemistry Chapter 2 (The Structure of Atom)Homi Institute
The document summarizes key concepts about the structure of atoms and types of radiation. It discusses three common types of radiation emitted during radioactive decay - alpha particles, beta particles, and gamma rays. It provides examples of nuclei that undergo alpha and beta decay, such as U-238 and Th-230. The document also explains that a beta particle is a high energy electron emitted from the nucleus during beta decay.
This document provides an overview of electron spin resonance (ESR) spectroscopy. It discusses how ESR works by applying a magnetic field to induce transitions between electron spin energy levels, which are split due to interactions between unpaired electrons and their environment. Specifically, it describes how orbital interactions and nuclear hyperfine interactions affect the ESR spectrum. It also discusses experimental considerations like microwave frequencies, magnetic field strengths, sensitivity, saturation effects, and nuclear hyperfine interactions. The goal is to provide fundamentals of ESR spectroscopy and introduce its capabilities for studying organic and organometallic radicals and complexes.
This document discusses the development of atomic structure models from the early 20th century to the present. It describes experiments that showed light and matter have both wave-like and particle-like properties. This led to the development of quantum mechanics and quantum numbers to describe electron orbitals. The Bohr model of the hydrogen atom was an early success but did not apply to other atoms. Modern quantum mechanics uses probability distributions and accounts for electron spin and the Pauli exclusion principle.
X-rays and gamma rays are both forms of electromagnetic radiation that are differentiated based on their source. X-rays are produced outside the nucleus when electrons interact with matter, while gamma rays are produced within atomic nuclei through nuclear reactions. X-rays have wavelengths ranging from about 10 nanometers down to 0.01 nanometers. They are commonly used in medical imaging and security screening due to their ability to pass through objects. X-rays are generated using X-ray tubes, which accelerate electrons toward a metal target to produce X-ray photons through braking radiation or characteristic radiation. The properties, generation, and absorption of X-rays are described.
Dissecting x ray_emitting_gas_around_the_center_of_our_galaxySérgio Sacani
1) The Chandra X-ray Observatory was used to observe the supermassive black hole at the center of the Milky Way, Sgr A*, for a total of 3 megaseconds.
2) The observations revealed extended X-ray emission around Sgr A* that aligns spatially with a surrounding disk of massive stars.
3) Spectral analysis ruled out low-mass stars as the origin of the X-ray emission and instead found evidence that the emission is from a radiatively inefficient accretion flow onto the black hole, with an outflow present.
The document discusses periodicity and how properties vary across periods and down groups in the periodic table. It specifically focuses on Period 3 elements (Na to Ar). Key points:
1) Atomic radius decreases across Period 3 as nuclear charge increases, attracting electrons more strongly. Radius increases down groups as atomic size increases.
2) Ionization energy generally increases across Period 3 as nuclear charge increases, requiring more energy to remove electrons. It decreases down groups as distance from nucleus increases.
3) Melting/boiling points are highest for metals/covalent networks and lower for weak molecular bonds. Electrical conductivity is highest for metals and lowest for nonmetals.
Crystal Structures and X-Ray Diffraction - Sultan LeMarcslemarc
Report on the investigation of the characteristics of X-rays by measuring the count rate of X-rays reflected off alkali halide crystals at varying angles of incidence and using the principles of Bragg’s law. The experiment probes into crystal structures using X-ray diffractometry and deduces the lattice constants and ionic radii using the Miller index notation. The experiment successfully computes the characteristic wavelengths of Copper and clearly demonstrates the effect of filters on spectrum intensities. The interpretation of Miller indices and diffraction patterns are effectively used to analyse crystalline structures and compare lattice arrangements. By Sultan LeMarc
This document discusses electromagnetic radiation and antenna fundamentals. It begins by defining an antenna as a transducer between transmission lines and the surrounding medium that allows efficient launching of electromagnetic waves. The key characteristics of antennas like frequency, mounting location, gain, polarization, and efficiency are discussed. The document then covers topics such as radiation patterns, directivity, power gain, near fields, far fields, and polarization. Dipole antennas and the Friis transmission equation are also summarized.
This document provides an overview of electromagnetic radiation, antenna fundamentals, and wave propagation. It discusses antennas as the linkage between circuits and electromagnetic fields. Key concepts covered include the electromagnetic spectrum, frequency-wavelength relationships, antenna radiation patterns, gain, directivity, polarization, and near, intermediate, and far field regions. Common antenna types for mobile communication like dipoles, monopoles, and arrays are also mentioned. Baluns are described as devices that convert between balanced and unbalanced signals.
This dissertation project examines the oscillation properties of coronal streamers after collisions with shock waves from coronal mass ejections (CMEs). The author developed an IDL program to calculate properties like wave speed, Alfvén speed, magnetic field, and magnetic tension force using electron density data from two CME/streamer collision events observed by the LASCO C2 coronagraph on SOHO. Results showed wave speed and Alfvén speed increased with height while density, magnetic field, and tension decreased with height. The study aimed to provide a method for calculating streamer wave properties to further understanding of coronal structures.
Effect of a_high_opacity_on_the_light_curves_of_radioactively_powered_transie...Sérgio Sacani
This document discusses how higher opacities from lanthanide elements in the ejecta of neutron star mergers could dramatically affect the predicted light curves of electromagnetic counterparts. The key points are:
1) Ab initio calculations show r-process element opacities are orders of magnitude higher than previously assumed iron opacities, particularly from lanthanide elements.
2) With these higher opacities, radiation transport models predict light curves that are longer (lasting about a week), dimmer, and redder, with emission peaked in the infrared rather than optical/ultraviolet.
3) A two-component light curve may result if there is both lanthanide-rich ejecta and a secondary
Similar to Voyager1 observes low_energy_galactic_cosmic_rays_in_a_region_depleted_of_heliospheric_ions (20)
Compositions of iron-meteorite parent bodies constrainthe structure of the pr...Sérgio Sacani
Magmatic iron-meteorite parent bodies are the earliest planetesimals in the Solar System,and they preserve information about conditions and planet-forming processes in thesolar nebula. In this study, we include comprehensive elemental compositions andfractional-crystallization modeling for iron meteorites from the cores of five differenti-ated asteroids from the inner Solar System. Together with previous results of metalliccores from the outer Solar System, we conclude that asteroidal cores from the outerSolar System have smaller sizes, elevated siderophile-element abundances, and simplercrystallization processes than those from the inner Solar System. These differences arerelated to the formation locations of the parent asteroids because the solar protoplane-tary disk varied in redox conditions, elemental distributions, and dynamics at differentheliocentric distances. Using highly siderophile-element data from iron meteorites, wereconstruct the distribution of calcium-aluminum-rich inclusions (CAIs) across theprotoplanetary disk within the first million years of Solar-System history. CAIs, the firstsolids to condense in the Solar System, formed close to the Sun. They were, however,concentrated within the outer disk and depleted within the inner disk. Future modelsof the structure and evolution of the protoplanetary disk should account for this dis-tribution pattern of CAIs.
Signatures of wave erosion in Titan’s coastsSérgio Sacani
The shorelines of Titan’s hydrocarbon seas trace flooded erosional landforms such as river valleys; however, it isunclear whether coastal erosion has subsequently altered these shorelines. Spacecraft observations and theo-retical models suggest that wind may cause waves to form on Titan’s seas, potentially driving coastal erosion,but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titanremain unknown. No widely accepted framework exists for using shoreline morphology to quantitatively dis-cern coastal erosion mechanisms, even on Earth, where the dominant mechanisms are known. We combinelandscape evolution models with measurements of shoreline shape on Earth to characterize how differentcoastal erosion mechanisms affect shoreline morphology. Applying this framework to Titan, we find that theshorelines of Titan’s seas are most consistent with flooded landscapes that subsequently have been eroded bywaves, rather than a uniform erosional process or no coastal erosion, particularly if wave growth saturates atfetch lengths of tens of kilometers.
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆Sérgio Sacani
Context. The early-type galaxy SDSS J133519.91+072807.4 (hereafter SDSS1335+0728), which had exhibited no prior optical variations during the preceding two decades, began showing significant nuclear variability in the Zwicky Transient Facility (ZTF) alert stream from December 2019 (as ZTF19acnskyy). This variability behaviour, coupled with the host-galaxy properties, suggests that SDSS1335+0728 hosts a ∼ 106M⊙ black hole (BH) that is currently in the process of ‘turning on’. Aims. We present a multi-wavelength photometric analysis and spectroscopic follow-up performed with the aim of better understanding the origin of the nuclear variations detected in SDSS1335+0728. Methods. We used archival photometry (from WISE, 2MASS, SDSS, GALEX, eROSITA) and spectroscopic data (from SDSS and LAMOST) to study the state of SDSS1335+0728 prior to December 2019, and new observations from Swift, SOAR/Goodman, VLT/X-shooter, and Keck/LRIS taken after its turn-on to characterise its current state. We analysed the variability of SDSS1335+0728 in the X-ray/UV/optical/mid-infrared range, modelled its spectral energy distribution prior to and after December 2019, and studied the evolution of its UV/optical spectra. Results. From our multi-wavelength photometric analysis, we find that: (a) since 2021, the UV flux (from Swift/UVOT observations) is four times brighter than the flux reported by GALEX in 2004; (b) since June 2022, the mid-infrared flux has risen more than two times, and the W1−W2 WISE colour has become redder; and (c) since February 2024, the source has begun showing X-ray emission. From our spectroscopic follow-up, we see that (i) the narrow emission line ratios are now consistent with a more energetic ionising continuum; (ii) broad emission lines are not detected; and (iii) the [OIII] line increased its flux ∼ 3.6 years after the first ZTF alert, which implies a relatively compact narrow-line-emitting region. Conclusions. We conclude that the variations observed in SDSS1335+0728 could be either explained by a ∼ 106M⊙ AGN that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGNobserved in the process of activating. If the latter were found to be the case, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour. Key words. galaxies: active– accretion, accretion discs– galaxies: individual: SDSS J133519.91+072807.4
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
"Frontline Battles with DDoS: Best practices and Lessons Learned", Igor IvaniukFwdays
At this talk we will discuss DDoS protection tools and best practices, discuss network architectures and what AWS has to offer. Also, we will look into one of the largest DDoS attacks on Ukrainian infrastructure that happened in February 2022. We'll see, what techniques helped to keep the web resources available for Ukrainians and how AWS improved DDoS protection for all customers based on Ukraine experience
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectorsDianaGray10
Join us to learn how UiPath Apps can directly and easily interact with prebuilt connectors via Integration Service--including Salesforce, ServiceNow, Open GenAI, and more.
The best part is you can achieve this without building a custom workflow! Say goodbye to the hassle of using separate automations to call APIs. By seamlessly integrating within App Studio, you can now easily streamline your workflow, while gaining direct access to our Connector Catalog of popular applications.
We’ll discuss and demo the benefits of UiPath Apps and connectors including:
Creating a compelling user experience for any software, without the limitations of APIs.
Accelerating the app creation process, saving time and effort
Enjoying high-performance CRUD (create, read, update, delete) operations, for
seamless data management.
Speakers:
Russell Alfeche, Technology Leader, RPA at qBotic and UiPath MVP
Charlie Greenberg, host
Northern Engraving | Modern Metal Trim, Nameplates and Appliance PanelsNorthern Engraving
What began over 115 years ago as a supplier of precision gauges to the automotive industry has evolved into being an industry leader in the manufacture of product branding, automotive cockpit trim and decorative appliance trim. Value-added services include in-house Design, Engineering, Program Management, Test Lab and Tool Shops.
What is an RPA CoE? Session 1 – CoE VisionDianaGray10
In the first session, we will review the organization's vision and how this has an impact on the COE Structure.
Topics covered:
• The role of a steering committee
• How do the organization’s priorities determine CoE Structure?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
inQuba Webinar Mastering Customer Journey Management with Dr Graham HillLizaNolte
HERE IS YOUR WEBINAR CONTENT! 'Mastering Customer Journey Management with Dr. Graham Hill'. We hope you find the webinar recording both insightful and enjoyable.
In this webinar, we explored essential aspects of Customer Journey Management and personalization. Here’s a summary of the key insights and topics discussed:
Key Takeaways:
Understanding the Customer Journey: Dr. Hill emphasized the importance of mapping and understanding the complete customer journey to identify touchpoints and opportunities for improvement.
Personalization Strategies: We discussed how to leverage data and insights to create personalized experiences that resonate with customers.
Technology Integration: Insights were shared on how inQuba’s advanced technology can streamline customer interactions and drive operational efficiency.
AppSec PNW: Android and iOS Application Security with MobSFAjin Abraham
Mobile Security Framework - MobSF is a free and open source automated mobile application security testing environment designed to help security engineers, researchers, developers, and penetration testers to identify security vulnerabilities, malicious behaviours and privacy concerns in mobile applications using static and dynamic analysis. It supports all the popular mobile application binaries and source code formats built for Android and iOS devices. In addition to automated security assessment, it also offers an interactive testing environment to build and execute scenario based test/fuzz cases against the application.
This talk covers:
Using MobSF for static analysis of mobile applications.
Interactive dynamic security assessment of Android and iOS applications.
Solving Mobile app CTF challenges.
Reverse engineering and runtime analysis of Mobile malware.
How to shift left and integrate MobSF/mobsfscan SAST and DAST in your build pipeline.
Discover top-tier mobile app development services, offering innovative solutions for iOS and Android. Enhance your business with custom, user-friendly mobile applications.
The Department of Veteran Affairs (VA) invited Taylor Paschal, Knowledge & Information Management Consultant at Enterprise Knowledge, to speak at a Knowledge Management Lunch and Learn hosted on June 12, 2024. All Office of Administration staff were invited to attend and received professional development credit for participating in the voluntary event.
The objectives of the Lunch and Learn presentation were to:
- Review what KM ‘is’ and ‘isn’t’
- Understand the value of KM and the benefits of engaging
- Define and reflect on your “what’s in it for me?”
- Share actionable ways you can participate in Knowledge - - Capture & Transfer
High performance Serverless Java on AWS- GoTo Amsterdam 2024Vadym Kazulkin
Java is for many years one of the most popular programming languages, but it used to have hard times in the Serverless community. Java is known for its high cold start times and high memory footprint, comparing to other programming languages like Node.js and Python. In this talk I'll look at the general best practices and techniques we can use to decrease memory consumption, cold start times for Java Serverless development on AWS including GraalVM (Native Image) and AWS own offering SnapStart based on Firecracker microVM snapshot and restore and CRaC (Coordinated Restore at Checkpoint) runtime hooks. I'll also provide a lot of benchmarking on Lambda functions trying out various deployment package sizes, Lambda memory settings, Java compilation options and HTTP (a)synchronous clients and measure their impact on cold and warm start times.
"Choosing proper type of scaling", Olena SyrotaFwdays
Imagine an IoT processing system that is already quite mature and production-ready and for which client coverage is growing and scaling and performance aspects are life and death questions. The system has Redis, MongoDB, and stream processing based on ksqldb. In this talk, firstly, we will analyze scaling approaches and then select the proper ones for our system.
Introduction of Cybersecurity with OSS at Code Europe 2024Hiroshi SHIBATA
I develop the Ruby programming language, RubyGems, and Bundler, which are package managers for Ruby. Today, I will introduce how to enhance the security of your application using open-source software (OSS) examples from Ruby and RubyGems.
The first topic is CVE (Common Vulnerabilities and Exposures). I have published CVEs many times. But what exactly is a CVE? I'll provide a basic understanding of CVEs and explain how to detect and handle vulnerabilities in OSS.
Next, let's discuss package managers. Package managers play a critical role in the OSS ecosystem. I'll explain how to manage library dependencies in your application.
I'll share insights into how the Ruby and RubyGems core team works to keep our ecosystem safe. By the end of this talk, you'll have a better understanding of how to safeguard your code.
Skybuffer SAM4U tool for SAP license adoptionTatiana Kojar
Manage and optimize your license adoption and consumption with SAM4U, an SAP free customer software asset management tool.
SAM4U, an SAP complimentary software asset management tool for customers, delivers a detailed and well-structured overview of license inventory and usage with a user-friendly interface. We offer a hosted, cost-effective, and performance-optimized SAM4U setup in the Skybuffer Cloud environment. You retain ownership of the system and data, while we manage the ABAP 7.58 infrastructure, ensuring fixed Total Cost of Ownership (TCO) and exceptional services through the SAP Fiori interface.
1. Reports
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A key objective of the Voyager Cosmic Ray Subsystem (1) is the deter-
mination of the intensity of galactic cosmic ray (GCR) nuclei and elec-
trons in the interstellar medium outside of the heliosphere. On 25 August
2012, Voyager 1 (V1) entered a region where the heliospheric ions were
depleted and replaced by low energy GCR nuclei and electrons. This
would have been expected had Voyager 1 crossed the heliopause, the
boundary separating the solar wind plasma and magnetic field from the
interstellar plasma and magnetic field. However, there was no change in
the direction of the magnetic field even though the field intensity abrupt-
ly increased by 60%, indicating that the magnetic field lines in this re-
gion originated at the sun, not from interstellar space (2). So, V1 appears
to have entered a new region that is depleted of energetic heliospheric
ions and accessible to low energy cosmic rays (see also (3, 4)).
The first indication of a heliospheric depletion region was observed
on 28 July 2012, when the intensity of ions from inside the heliosphere
with energies 0.5 MeV ≤ E ≤ 60 MeV abruptly decreased and subse-
quently recovered 5 days later (counting rates C and D in Fig. 1). A sec-
ond decrease on 13 August lasted 8 days and was followed 4 days later
by the durable entry of V1 into the heliospheric depletion region on 25
August. The magnetic field increased simultaneously with the decreases
in energetic ions, suggesting that lower energy plasma may also have
escaped, with the resulting decrease in plasma pressure leading to a
compression of the magnetic field (2).
The intensity changes for four distinct populations of energetic parti-
cles are strongly correlated as shown in Fig. 1. Because of their small
mass, the GCR electrons have the smallest radii of gyration around the
magnetic field lines, typically 0.0006 AU for a 10 MeV electron in a
heliosheath magnetic field of 0.4 nT. Because V1 crosses that distance in
<1.5 hours, the electrons provide the sharpest indication of when V1
crossed the boundary of the region where there is enhanced access of
GCRs from outside. The edges of the regions of enhanced electron in-
tensities are closely aligned with the five boundaries of the regions of
enhanced magnetic field that occurred on DOY 210.6, 215.6, 225.7,
233.5, and 237.7 (2). The heavier ions have larger gyroradii that result in
broader intensity transitions as seen in
the counting rate of >70 MeV cosmic
ray nuclei. For example, V1 crosses the
0.025 AU gyroradius of a 100 MeV
proton in ~2.5 days. Anomalous cosmic
rays (ACRs) are also accelerated in the
outer heliosphere and at energies below
~100 MeV/nucleon their intensity
greatly exceeds that of GCRs. As seen
by the intensity of 7-60 MeV protons in
Fig. 1, the intensities of ACRs also
decrease in the depletion regions as
they escape out of the heliosphere.
Their disappearance beginning on DOY
238 reveals the intensity of GCRs of the
same energy that have flowed into the
depletion region from outside.
Voyager has four Low Energy Tel-
escopes (LETs) arranged in an orthogo-
nal array (1). As illustrated in Fig. 2,
there are significant differences in in-
tensity among the telescopes over ex-
tended periods. LET D is oriented so
that it observes protons with pitch an-
gles of 75 ± 25° to the spiral magnetic
field which is pointing outward along
the spiral direction (2), so LET D is
sensitive to ions moving outward along
the field (θ<90°) and also inward
(θ>90°). LET C observes protons with pitch angles of 135 ± 25°, so it is
sensitive to ions coming inward along the spiral field.
These ions originate at the termination shock or in the heliosheath
and diffuse mainly along the spiral magnetic field. Before 28 July, there
was sufficient scattering on the field line that the intensity of ions in LET
C was the same as in LET D. However, during the first two decreases,
the intensity of ions diffusing inward toward LET C was significantly
lower than in LET D, indicating some of the ions spiraling outward were
lost and not scattered back toward V1.
Following the boundary crossing on 25 August (DOY 238), the in-
tensity of H ions (protons) in LET C dropped much more rapidly than
the intensity of protons in LET D. The two rates converged following
2012.72 (DOY 263), indicating that low energy protons from the helio-
sphere were no longer dominating the intensity near 5 MeV at V1. In-
stead, the intensity was isotropic as expected if the remaining protons are
low energy GCRs diffusing in along the magnetic field.
Figure 2 also shows similar anisotropies for He and O. Although
longer time averages are required due to the lower intensities, there is
evidence for losses in LET C during the events prior to DOY 238 and for
extended periods following when the outward flow was observed in LET
D, while LET C was already observing a lower intensity of isotropic
galactic cosmic rays diffusing inward along the magnetic field. The
longer persistence of the heavier heliospheric ions is consistent with the
expectation that singly ionized 5 MeV/nucleon He+
and 9 MeV/nucleon
O+
with gyroradii of 0.022 and 0.12 AU, respectively, will have larger
scattering mean free paths and will be scattered into the loss cone more
slowly than 5 MeV H+
that has a gyroradius of 0.0054 AU.
The disappearance of most of the heliospheric ions after 25 August
2012, provides an opportunity to examine the energy spectra of GCRs to
lower energies than previously possible (4). Figure 2 shows that GCR H
and He dominate the 3-7.8 MeV/nucleon energy range from approxi-
mately 2012.77 (DOY 282) onward, as the intensity apparently became
isotropic at that time, consistent with the expectation for GCRs. Figure 3
shows the energy spectra for the period 2012/303-366 for H and He from
Voyager 1 Observes Low-Energy
Galactic Cosmic Rays in a Region
Depleted of Heliospheric Ions
E. C. Stone,1
* A. C. Cummings,1
F. B. McDonald,2
† B. C. Heikkila,3
N. Lal,3
W. R. Webber4
1
California Institute of Technology, Pasadena, CA 91125, USA.
2
University of Maryland, College Park, MD
20742, USA.
3
NASA/Goddard Spaceflight Center, Greenbelt, MD 20771, USA.
4
New Mexico State
University, Las Cruces, NM 88003, USA.
*Corresponding author. E-mail: ecs@srl.caltech.edu
†Deceased
On 25 August 2012, Voyager 1 was at 122 astronomical units when the steady
intensity of low-energy ions it had observed for the last 6 years suddenly dropped
for a third time and soon completely disappeared as the ions streamed away into
interstellar space. Although the magnetic field observations indicate that Voyager 1
remained inside the heliosphere, the intensity of cosmic ray nuclei from outside the
heliosphere abruptly increased. We report the spectra of galactic cosmic rays down
to ~3 × 106
electron volts per nucleon, revealing H and He energy spectra with broad
peaks from 10 × 106
to 40 × 106
electron volts per nucleon and an increasing galactic
cosmic ray electron intensity down to ~10 × 106
electron volts.
onJune27,2013www.sciencemag.orgDownloadedfrom
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1.8 to several hundred MeV/nucleon along with an energy spectrum of H
from a period prior to the onset of the recent activity. This reference
spectrum shows the dominance of the spectrum by the Termination
Shock Particle and ACR heliospheric populations of particles below
~100 MeV/nucleon during this time. These particles have largely
streamed away in the more recent period (DOY 303-366), replaced by
the inflow of low-energy GCRs. A small turn up in the energy spectra of
H and He below ~2 MeV/nucleon, suggests a remnant heliospheric ion
population may be present at the lowest energies.
However, it is uncertain whether GCRs have fully unimpeded access
into this new region. In addition, the GCR intensity immediately outside
the heliosphere may be lower than the galactic intensity due to modula-
tion in the local interstellar medium (5–7). Recent models indicate a
reduction of ~25 to ~40% in the intensity of 100 MeV protons, with
corresponding positive radial gradients of ~0.5 and ~0.9%/AU near the
heliopause (7), although other models suggest there should be no inter-
stellar gradient (8). The time dependence of the observed intensities after
the disappearance of heliospheric protons (DOY 270 to 366 in Fig. 1)
correspond to gradients of -1.4 ± 0.9%/AU for 7-60 MeV protons and -
1.0 ± 0.4%/AU for >70 MeV GCR nuclei, mainly protons. The gradient
of 6-100 MeV electrons is also small, only -0.6 ± 0.6%/AU from DOY
239 to 366. Thus, there is no evidence for a positive radial gradient in
the current region.
The GCR H and He spectra have the same shape from ~3 – 346
MeV/nucleon. The H/He ratio has been determined in three energy rang-
es corresponding to different telescope and/or operation modes of the
instrument. In the lowest energy band, 3-7.8 MeV/nucleon, we find the
H/He ratio to be 11.9 ± 0.4. In the 7.8 – 57 MeV/nucleon band, the ratio
is 12.9 ± 0.6, and in the highest energy interval, 134-346 MeV/nucleon,
the ratio is 12.6 ± 0.3. These uncertainties are purely statistical and there
may be systematic uncertainties as well. However, the reasonably good
agreement of the ratios across the range from 3 to 346 MeV/nucleon
suggests that systematic uncertainties are likely small. The peak intensi-
ties of the GCR spectra of H and He are in the ~10-40 MeV/nucleon
energy range.
The H/He ratio of 12.9 ± 0.6 in the energy region of the peak in the
spectra is consistent with the recommended abundance in the solar pho-
tosphere, 12.6 (9). It differs from previous cosmic ray observations of
4.7 ±0.5 at 100 MeV/nucleon observed at 1 AU where the spectra and
abundance ratios are modified by the effects of solar modulation (10). It
also differs from the ACR ratio of 4.1 (11), indicating that ACRs do not
dominate GCRs outside the heliosphere as has been suggested (12).
Only the leaky box model of Ip and Axford (13) addresses the low-
energy portion of the GCR spectra (Fig. 3). Their model appears to have
approximately the right peak intensity for H but the energy of the peak is
lower than observed. For He both the peak intensity and energy of the
peak are somewhat displaced from the observations. At higher energies,
>70 MeV/nucleon, the leaky box model spectra from Webber and Higbie
(14) are in good agreement with the observed H and He spectra.
Also shown in Fig. 3 are C and O spectra for 2012/261-366. This
longer period improves the statistical significance of the observations
and is justified by the intensity vs. time profile of O with 5.4-13.9
MeV/nucleon for LETs A, B, and C shown in Fig. 2. In constructing the
energy spectra for O in Fig. 3, the LET D telescope was not used as it
has a more persistent heliospheric contribution due to its bore sight look-
ing nearly perpendicular to the magnetic field direction. Even ignoring
LET D, there may be some residual heliospheric contribution present
below ~10 MeV/nucleon. The C and O energy spectra above ~10
MeV/nucleon are very similar with the peak C intensity occurring at ~70
MeV/nucleon. The C/O ratio for the energy range 21.6 – 106
MeV/nucleon is 0.95 ± 0.06, consistent with GCR observations at higher
energies at 1 AU (10, 15), and not with the ACR ratio of 0.005 (11). All
previous measurements below ~100 MeV/nucleon represent particles
decelerated from much higher energies by the solar modulation process.
The intensity of electrons with ~6-100 MeV had jumps in concert
with the GCR nuclei (Fig. 1), indicating that V1 is observing GCR elec-
trons in this energy range as opposed to electrons accelerated in the heli-
osphere. The ratio of intensities of the two periods shown in Fig. 4 is
approximately a factor of two over the energy range shown, indicating
an energy independent diffusive mean free path for 6-60 MeV electrons.
The energy spectrum for the new region is proportional to E-1.45 ± 0.09
and has a spectral shape that is very similar to the theoretical estimates
of the interstellar electron spectrum of Ip and Axford (13) and Langner
et al. (16), but the overall intensity is about a factor of two below those
estimates. The observed intensity exceeds an extrapolation of the spec-
trum from a diffusion model by Strong et al. (17) that assumes an elec-
tron source spectrum proportional to E−1.6
below a few GeV as implied
by fits to radio synchrotron emission. A source spectrum of E−2
would
better match the electron spectrum (Fig. 4), but would not be consistent
with the radio observations without other adjustments to the model.
The presence of a region having a spiral magnetic field, but depleted
of energetic heliospheric particles and accessible by low energy galactic
cosmic ray nuclei and electrons, is an important feature of the interaction
between the heliosphere and the local interstellar medium. It has been
suggested that this could be a disconnection region where the spiral field
has been convected far enough beyond the termination shock so that
there is not an effective connection to the source of anomalous cosmic
rays at the termination shock (18). Further development of this and other
possible models will benefit our understanding of the region beyond 122
AU that Voyager 1 is now exploring.
References and Notes
1. E. C. Stone, R. E. Vogt, F. B. McDonald, B. J. Teegarden, J. H. Trainor, J. R.
Jokipii, W. R. Webber, Cosmic Ray Investigation for the Voyager Missions:
Energetic Particle Studies in the Outer Heliosphere - and Beyond. Space Sci.
Rev. 21, 355 (1977). doi:10.1007/BF00211546
2. L. F. Burlaga, N. F. Ness, E. C. Stone, Magnetic Field Observations of the
Entry of Voyager 1 into the Heliosheath Depletion Region. Science 340, xxx
(2013).
3. S. M. Krimigis et al., Search for the Exit: Voyager 1 at Heliosphere's Border
with the Galaxy. Science 340, xxx (2013).
4. W. R. Webber, F. B. McDonald, Recent Voyager 1 data indicate that on 25
August 2012 at a distance of 121.7 AU from the Sun, sudden and
unprecedented intensity changes were observed in anomalous and galactic
cosmic rays. Geophys. Res. Lett. •••, 1 (2013).
5. K. Herbst, B. Heber, A. Kopp, O. Sternal, F. Steinhilber, The Local Interstellar
Spectrum beyond the Heliopause: What can be Learned from Voyager in the
Inner Heliosheath? Astrophys. J. 761, 17 (2012). doi:10.1088/0004-
637X/761/1/17
6. K. Scherer, H. Fichtner, R. D. Strauss, S. E. S. Ferreira, M. S. Potgieter, H.-J.
Fahr, On Cosmic Ray Modulation beyond the Heliopause: Where is the
Modulation Boundary? Astrophys. J. 735, 128 (2011). doi:10.1088/0004-
637X/735/2/128
7. R. D. Strauss, M. S. Potgieter, S. E. S. Ferreira, H. Fichtner, K. Scherer,
Cosmic Ray Modulation Beyond the Heliopause: A Hybrid Modeling
Approach. Astrophys. J. 765, L18 (2013). doi:10.1088/2041-8205/765/1/L18
8. J. R. Jokipii, Cosmic Rays in the Outer Heliosphere and Nearby Interstellar
Medium. The Outer Heliosphere: The Next Frontiers, ed. K.Scherer, H.
Fichtner, H. J. Fahr, E. Marsch, 513 (New York: Pergamon Press 2001).
9. K. Lodders, Solar System Abundances and Condensation Temperatures of the
Elements. Astrophys. J. 591, 1220–1247 (2003). doi:10.1086/375492
10. J. A. Simpson, Elemental and Isotopic Composition of the Galactic Cosmic
Rays. Annu. Rev. Nucl. Part. Sci. 33, 323–382 (1983).
doi:10.1146/annurev.ns.33.120183.001543
11. A. C. Cummings, E. C. Stone, C. D. Steenberg, Composition of Anomalous
Cosmic Rays and Other Heliospheric Ions. Astrophys. J. 578, 194–210
(2002). doi:10.1086/342427
12. K. Scherer, H. Fichtner, S. E. S. Ferreira, I. Büsching, M. S. Potgieter, Are
Anomalous Cosmic Rays the Main Contribution to the Low-Energy Galactic
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Cosmic Ray Spectrum? Astrophys. J. 680, L105–L108 (2008).
doi:10.1086/589969
13. W.-H. Ip, W. I. Axford, Estimates of galactic cosmic ray spectra at low
energies. Astron. Astrophys. 149, 7 (1985).
14. W. R. Webber, P. R. Higbie, Galactic propagation of cosmic ray nuclei in a
model with an increasing diffusion coefficient at low rigidities: A comparison
of the new interstellar spectra with Voyager data in the outer heliosphere. J.
Geophys. Res. 114, (A2), 02103 (2009). doi:10.1029/2008JA013689
15. J. S. George, K. A. Lave, M. E. Wiedenbeck, W. R. Binns, A. C. Cummings,
A. J. Davis, G. A. de Nolfo, P. L. Hink, M. H. Israel, R. A. Leske, R. A.
Mewaldt, L. M. Scott, E. C. Stone, T. T. von Rosenvinge, N. E. Yanasak,
Elemental Composition and Energy Spectra of Galactic Cosmic Rays During
Solar Cycle 23. Astrophys. J. 698, 1666–1681 (2009). doi:10.1088/0004-
637X/698/2/1666
16. U. W. Langner, O. C. de Jager, M. S. Potgieter, in Proc. 27th International
Cosmic Ray Conference. (Hamburg, 2001), vol. 10, pp. 3992-3995.
17. A. W. Strong, E. Orlando, T. R. Jaffe, The interstellar cosmic-ray electron
spectrum from synchrotron radiation and direct measurements. Astron.
Astrophys. 534, 54 (2011). doi:10.1051/0004-6361/201116828
18. D. J. McComas, N. A. Schwadron, Disconnection from the Termination
Shock: The End of the Voyager Paradox. Astrophys. J. 758, 19 (2012).
doi:10.1088/0004-637X/758/1/19
19. I. V. Moskalenko, A. W. Strong, J. F. Ormes, M. S. Potgieter, Secondary
Antiprotons and Propagation of Cosmic Rays in the Galaxy and Heliosphere.
Astrophys. J. 565, 280–296 (2002). doi:10.1086/324402
20. L. A. Fisk, G. Gloeckler, Acceleration of Galactic Cosmic Rays in the
Interstellar Medium. Astrophys. J. 744, 127 (2012). doi:10.1088/0004-
637X/744/2/127
21. W. R. Webber, P. R. Higbie, Limits on the interstellar cosmic ray electron
spectrum below ~1-2 GeV derived from the galactic polar radio spectrum and
constrained by new Voyager 1 measurements. J. Geophys. Res. 113, (A11),
11106 (2008). doi:10.1029/2008JA013386
Acknowledgments: This work was supported by NASA (NNN12A012). This
paper is dedicated to the memory of Frank McDonald whose leadership in the
cosmic ray investigation on Voyager began in 1972. His contributions
continued until the day of his passing just after Voyager 1 durably entered the
depletion region and fulfilled his vision of observing low energy galactic
cosmic rays from the local interstellar medium. This paper benefited
substantially from discussions during meetings of the International Team on
the Physics of the Heliopause at the International Space Science Institute in
Bern, Switzerland.
Supplementary Materials
www.sciencemag.org/cgi/content/full/science.1236408/DC1
Supplementary Text
Fig. S1
References
11 February 2013; accepted 24 May 2013
Published online 27 June 2013
10.1126/science.1236408
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Fig. 1. The counting rates (6-hour averages) of four different energetic particle
species in the vicinity of the depletion region. (A) (y-axis on right) GCR nuclei
(mainly protons with E>70 MeV) penetrating the High Energy Telescope 1 (HET
1). (B) (y-axis on left) GCR electrons with energies between 6 and ~100 MeV
observed by the Electron Telescope (TET). (C) (y-axis on left) Protons with 7 to
60 MeV stopping in HET 1 (rate shown is divided by 11.55) are mainly anomalous
cosmic rays before 2012/238 (25 August) and galactic cosmic rays after that. (D)
(y-axis on left) Low energy particles observed in the LET A (rate shown is divided
by 124.5) are mainly protons with 0.5 to ~30 MeV accelerated at the termination
shock and in the heliosheath plus a background rate of 0.017 s
−1
due to higher
energy nuclei. Three distinct periods in 2012 on days 210-215 (28 July-2 Aug),
226-233 (13-20 Aug), and from 238 (25 Aug.) are indicated by vertical lines
corresponding to the magnetic boundaries of the depletion region (2). The
simultaneous intensity changes coincide with abrupt increases and decreases in
the magnitude of the magnetic field, suggesting that after two brief encounters
with a depletion region or regions, V1 durably entered a broad depletion region on
28 August (DOY 238).
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Fig. 2. Intensities of H, He, and O from V1 for the last half of 2012. (A) 1-day
average intensities of H with 3.0 – 7.8 MeV. Intensities are shown for two of the
four LET telescopes (see (1) for arrangement of the telescopes). The bore sight of
LET D is approximately pointed perpendicular to the magnetic field direction. The
bore sight of LET C is oriented at 90 degrees to that of LET D. (B) Similar to A
except for 13-day averages of the intensities of He with 3.0 – 7.8 MeV/nucleon.
(C) Similar to B except for O with 5.4 - 13.9 MeV/nucleon and the average
intensity from the LET A, B, and C telescopes is plotted instead of only LET C, in
order to improve the statistical significance of the result. The LET A bore sight is
oppositely directed to that of LET C and the bore sights of LET A, B, and D form
an orthogonal set.
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Fig. 3. Differential energy spectra of H, He, C, and O
from V1. Two spectra are shown for H: one for a
reference period before the depletion region was
reached, 2011/274 – 2012/121, and one for a new period
within the depletion region, 2012/303-366. For these two
H spectra and the He spectrum, intensities from all four
LET telescopes were averaged together for E > 3
MeV/nuc. At higher energies, >57 MeV/nuc, intensities
from only the HET 2 telescope are shown. For C,
intensities from all four LET telescopes were used and at
higher energies, >20 MeV/nucleon, intensities from both
HET telescopes were averaged together. For O with 5.4-
17.1 MeV/nucleon, only LET telescopes A, B, and C
were used in order to minimize the contribution from
heliospheric particles. For O with 17.1-21.6
MeV/nucleon, HET 2 only was used and for energies
>21.6 MeV/nucleon, intensities from both HETs were
averaged together. The C and O spectra are for the
period 2012/261-366. Several estimates of the local
interstellar galactic cosmic ray H and He spectra are
shown. The solid lines are model a from Ip and Axford
(13). The dotted lines represent the leaky box model
from Webber and Higbie (14). The dashed lines are the
DC model from Moskalenko et al. (19), and the dot-dash
line for H is from Fisk and Gloeckler (20).
Fig. 4. Differential energy spectra of electrons from the
V1 TET telescope. Two pairs of spectra are shown, one
pair for a reference period before the new region was
reached, 2011/274 – 2012/121, and one pair for a period
within the new region, 2012/303-366. The open symbols
represent spectra derived using response functions from
a pre-launch accelerator calibration. The solid symbols
use response functions from a GEANT4 simulation. The
intensity differences in the closed and open symbols for
a given period are an indication of the systematic
uncertainly in the electron spectrum that is proportional
to E
-1.45 ± 0.09
in the new region. The method used in
deriving the energy spectra is described in the
Supplementary Materials. Three estimates of the local
interstellar galactic cosmic ray electron spectrum are
shown. The solid line is model a from Ip and Axford (13),
the dot-dash line represents model IS7 from Webber and
Higbie (21), the short-dashed line represents the polar
model from Langner et al. (16), the long-dashed and
dotted lines from Strong et al. (17) for electron source
spectra proportional to E
−1.6
and E
−2.0
respectively and
include positrons.
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