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Titan is a moon of Saturn with a dense nitrogen-methane atmosphere that allows for organic chemistry on its surface. The Cassini mission and Huygens probe provided data about Titan's surface, which appears to have liquid methane and ethane at some point in its history. Evidence suggests Titan has an internal liquid water layer that allows geological activity like cryovolcanism, and that ammonia plays a key role in maintaining this layer and Titan's evolution.
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In situ collection of dust grainsfalling from Saturn’s rings intoits atmosphere
The Cassini spacecraft detected dust grains falling from Saturn's rings into its atmosphere using an onboard cosmic dust analyzer (CDA). The CDA collected nanometer-sized dust grains during Cassini's final orbits between Saturn and its inner D ring. Analysis found the dust was predominantly tens of nanometers in size and composed of water ice and silicates. The silicate content of 8-30% was higher than inferred from previous ring observations. Spatial distribution data showed the dust flux was highest at the ring plane and varied with the CDA's orientation, providing evidence that the dust originated from the rings and was influenced by Saturn's offset magnetic field into its atmosphere.
My student handout
- Saturn has the most extensive ring system in the solar system, consisting of ice and dust particles orbiting the planet. It has several moons within its rings.
- Titan is Saturn's largest moon, composed of ice and rock. It is the only known moon with a dense nitrogen-rich atmosphere and contains lakes of liquid methane and ethane.
- Cassini's radar images provided the first evidence of liquid on Titan's surface in the form of large lakes, suggesting weather patterns similar to Earth's.
Cassini huygens with_video_placeholder
Cassini has been orbiting Saturn since 2004, conducting numerous science investigations of the planet, its rings and moons. It discovered water plumes erupting from Enceladus, signs of possible oceans and organic activity on Titan, and continues monitoring Saturn's weather, rings and developing new insights into the moons. Cassini remains in excellent health and its Solstice mission extends through 2017, promising more discoveries to come from this unprecedented exploration of the Saturn system.
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The international Cassini-Huygens spacecraft was launched on October 15, 1997 and had a marathon 7-year 2-billion mile journey to the distant planet Saturn. The 23-foot tall, 14-foot wide, 6-ton spacecraft is the largest most sophisticated outer planet spacecraft ever built, and is in its third year of operation in orbit around the planet Saturn. Cassini-Huygens has been returning extraordinary data about the entire Saturn system: the spectacular rings; the numerous icy satellites with a variety of unique surface features; the giant planet itself; a huge magneto-sphere teeming with particles that interact with the rings and moons; and the intriguing moon Titan, which is slightly larger than the planet Mercury, and whose hazy atmosphere is denser than that of Earth. This talk will be an overview of the Cassini-Huygens mission to Saturn with a summary of the top science returns of its first three years in orbit.
The Minnesota Space Grant Consortium, run out of the Department of Aerospace Engineering and Mechanics at the University of Minnesota, hosts Trina Ray of NASA JPL on January 22, 2008.
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Past remote observations of
Saturn by Pioneer 11, Voyager 1 and 2, Earthbased
observatories, and the Cassini prime and
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from the rings to the atmosphere. This would
modify the chemistry of Saturn’s upper atmosphere
and ionosphere. In situ observations
during the Cassini Grand Finale provided an
opportunity to study this chemical interaction
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- Titan is Saturn's largest moon, composed of ice and rock. It is the only known moon with a dense nitrogen-rich atmosphere and contains lakes of liquid methane and ethane.
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Cassini huygens with_video_placeholder
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The Minnesota Space Grant Consortium, run out of the Department of Aerospace Engineering and Mechanics at the University of Minnesota, hosts Trina Ray of NASA JPL on January 22, 2008.
Chemical interactions between Saturn’s atmosphere and its rings
Past remote observations of
Saturn by Pioneer 11, Voyager 1 and 2, Earthbased
observatories, and the Cassini prime and
solstice missions suggested an inflow of water
from the rings to the atmosphere. This would
modify the chemistry of Saturn’s upper atmosphere
and ionosphere. In situ observations
during the Cassini Grand Finale provided an
opportunity to study this chemical interaction
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1) ALMA observations of the protoplanetary disk around HD 142527 reveal diffuse CO gas and denser HCO+ filaments inside the dust gap.
2) The HCO+ filaments extend from the outer disk towards the inner disk and star, indicating gas flowing across the gap.
3) Estimates of the gas flow rate through the filaments are sufficient to sustain the observed rate of accretion onto the star, supporting the interpretation that the filaments are planet-induced gap-crossing accretion streams.
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On 19 Feb. 2016 nine Rosetta instruments serendipitously observed an outburst of gas and dust
from the nucleus of comet 67P/Churyumov-Gerasimenko. Among these instruments were cameras
and spectrometers ranging from UV over visible to microwave wavelengths, in-situ gas, dust and
plasma instruments, and one dust collector. At 9:40 a dust cloud developed at the edge of an image
in the shadowed region of the nucleus. Over the next two hours the instruments recorded a signature
of the outburst that signi cantly exceeded the background. The enhancement ranged from 50% of
the neutral gas density at Rosetta to factors >100 of the brightness of the coma near the nucleus.
Dust related phenomena (dust counts or brightness due to illuminated dust) showed the strongest
enhancements (factors >10). However, even the electron density at Rosetta increased by a factor 3
and consequently the spacecraft potential changed from 16V to 20V during the outburst. A
clear sequence of events was observed at the distance of Rosetta (34 km from the nucleus): within 15
minutes the Star Tracker camera detected fast particles ( 25 ms 1) while 100 m radius particles
were detected by the GIADA dust instrument 1 hour later at a speed of 6 ms 1. The slowest
were individual mm to cm sized grains observed by the OSIRIS cameras. Although the outburst
originated just outside the FOV of the instruments, the source region and the magnitude of the
outburst could be determined.
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Proxima b is a planet with a minimum mass of 1.3 M⊕ orbiting within the habitable zone (HZ) of Proxima Centauri, a very low-mass,
active star and the Sun’s closest neighbor. Here we investigate a number of factors related to the potential habitability of Proxima b
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and show that the planet currently receives 30 times more EUV radiation than Earth and 250 times more X-rays. We compute the time
evolution of the star’s spectrum, which is essential for modeling the flux received over Proxima b’s lifetime. We also show that Proxima
b’s obliquity is likely null and its spin is either synchronous or in a 3:2 spin-orbit resonance, depending on the planet’s eccentricity and
level of triaxiality. Next we consider the evolution of Proxima b’s water inventory. We use our spectral energy distribution to compute
the hydrogen loss from the planet with an improved energy-limited escape formalism. Despite the high level of stellar activity we find
that Proxima b is likely to have lost less than an Earth ocean’s worth of hydrogen (EOH) before it reached the HZ 100–200 Myr after
its formation. The largest uncertainty in our work is the initial water budget, which is not constrained by planet formation models. We
conclude that Proxima b is a viable candidate habitable planet.
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We are conducting a survey for distant solar system objects beyond the Kuiper
Belt edge ( 50 AU) with new wide-field cameras on the Subaru and CTIO tele-
scopes. We are interested in the orbits of objects that are decoupled from the
giant planet region in order to understand the structure of the outer solar sys-
tem, including whether a massive planet exists beyond a few hundred AU as first
reported in Trujillo and Sheppard (2014). In addition to discovering extreme
trans-Neptunian objects detailed elsewhere, we have found several objects with
high perihelia (q > 40 AU) that differ from the extreme and inner Oort cloud
objects due to their moderate semi-major axes (50 < a < 100 AU) and eccen-
tricities (e . 0.3). Newly discovered objects 2014 FZ71 and 2015 FJ345 have
the third and fourth highest perihelia known after Sedna and 2012 VP113, yet
their orbits are not nearly as eccentric or distant. We found several of these high
perihelion but moderate orbit objects and observe that they are mostly near Nep-
tune mean motion resonances and have significant inclinations (i > 20 degrees).
These moderate objects likely obtained their unusual orbits through combined
interactions with Neptune’s mean motion resonances and the Kozai resonance,
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2 and a mass of about 12 per cent the mass of the
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days,3 and its quiescent activity levels and X-ray luminosity4 are comparable to the Sun’s. New
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features, including the Ca II H+K lines and the G-band, and no detected emission lines. Its radial velocity of
cz=6280±120 km s−1 is within the 1σ velocity dispersion of the Coma cluster. The galaxy has an effective
radius of 4.3 ± 0.3 kpc and a Sérsic index of 0.89 ± 0.06, as measured from Keck imaging. We find no indications
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sparsely populated region of the size—magnitude plane of quiescent stellar systems, as they are ∼6 mag fainter
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come within a few parsecs. Such encounters could influence the solar system, for example through gravitational perturbations of the
Oort cloud. 16 stars are found to come within 2 pc (although a few of these have dubious data). This is fewer than were found in a
similar study based on Hipparcos data, even though the present study has many more candidates. This is partly because I reject stars
with large radial velocity uncertainties (>10 km s−1
), and partly because of missing stars in GDR1 (especially at the bright end). The
closest encounter found is Gl 710, a K dwarf long-known to come close to the Sun in about 1.3 Myr. The Gaia astrometry predict
a much closer passage than pre-Gaia estimates, however: just 16 000 AU (90% confidence interval: 10 000–21 000 AU), which will
bring this star well within the Oort cloud. Using a simple model for the spatial, velocity, and luminosity distributions of stars, together
with an approximation of the observational selection function, I model the incompleteness of this Gaia-based search as a function
of the time and distance of closest approach. Applying this to a subset of the observed encounters (excluding duplicates and stars
with implausibly large velocities), I estimate the rate of stellar encounters within 5 pc averaged over the past and future 5 Myr to be
545±59 Myr−1
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to 87 ± 9 Myr−1 within 2 pc. A more accurate analysis and assessment will be possible with future Gaia data releases.
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AAS National Conference 2008: Candice Hansen
The Titan Saturn System Mission (TSSM) is a proposed joint NASA-ESA mission to conduct in-depth exploration of Titan and Enceladus. The mission would include an orbiter carrying instruments to study Titan's atmosphere, surface and interior. It would also deploy a hot air balloon and lake lander to conduct in situ measurements. The orbiter would tour Saturn's system for over 9 years, performing multiple close flybys of Titan and Enceladus to advance understanding of processes on these moons beyond what was possible with the Cassini-Huygens mission.
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This document provides information about the planets in our solar system as well as asteroids, comets, and other celestial bodies. It details facts about each planet such as composition, size, atmospheric conditions, moons, and spacecraft missions. Key points include: the terrestrial planets like Earth are rocky, while the gas giants like Jupiter and Saturn have thick atmospheres composed primarily of hydrogen and helium; Venus' dense carbon dioxide atmosphere creates intense heat; Mars once had water and the potential for life; and asteroids and comets originate from the asteroid belt between Mars and Jupiter and the Kuiper Belt beyond Neptune's orbit. Spacecraft missions have revealed details of planets, moons, rings and other features of our solar system.
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The document summarizes NASA's past and current Mars missions, which have provided evidence that Mars once had liquid water and a thicker atmosphere capable of supporting life. Missions like Curiosity and MAVEN aim to determine the extent to which Mars' environment could have supported microbial life and what caused the planet to lose its atmosphere and surface water over time. While Mars cannot support liquid water on its surface today due to low temperatures and pressure, past missions have found evidence of dried riverbeds, minerals formed by acidic water, and large quantities of underground ice, indicating Mars was once significantly warmer and wetter.
The 19 Feb. 2016 Outburst of Comet 67P/CG: An ESA Rosetta Multi-Instrument Study
On 19 Feb. 2016 nine Rosetta instruments serendipitously observed an outburst of gas and dust
from the nucleus of comet 67P/Churyumov-Gerasimenko. Among these instruments were cameras
and spectrometers ranging from UV over visible to microwave wavelengths, in-situ gas, dust and
plasma instruments, and one dust collector. At 9:40 a dust cloud developed at the edge of an image
in the shadowed region of the nucleus. Over the next two hours the instruments recorded a signature
of the outburst that signi cantly exceeded the background. The enhancement ranged from 50% of
the neutral gas density at Rosetta to factors >100 of the brightness of the coma near the nucleus.
Dust related phenomena (dust counts or brightness due to illuminated dust) showed the strongest
enhancements (factors >10). However, even the electron density at Rosetta increased by a factor 3
and consequently the spacecraft potential changed from 16V to 20V during the outburst. A
clear sequence of events was observed at the distance of Rosetta (34 km from the nucleus): within 15
minutes the Star Tracker camera detected fast particles ( 25 ms 1) while 100 m radius particles
were detected by the GIADA dust instrument 1 hour later at a speed of 6 ms 1. The slowest
were individual mm to cm sized grains observed by the OSIRIS cameras. Although the outburst
originated just outside the FOV of the instruments, the source region and the magnitude of the
outburst could be determined.
The habitability of Proxima Centauri b - I. Irradiation, rotation and volatil...
Proxima b is a planet with a minimum mass of 1.3 M⊕ orbiting within the habitable zone (HZ) of Proxima Centauri, a very low-mass,
active star and the Sun’s closest neighbor. Here we investigate a number of factors related to the potential habitability of Proxima b
and its ability to maintain liquid water on its surface. We set the stage by estimating the current high-energy irradiance of the planet
and show that the planet currently receives 30 times more EUV radiation than Earth and 250 times more X-rays. We compute the time
evolution of the star’s spectrum, which is essential for modeling the flux received over Proxima b’s lifetime. We also show that Proxima
b’s obliquity is likely null and its spin is either synchronous or in a 3:2 spin-orbit resonance, depending on the planet’s eccentricity and
level of triaxiality. Next we consider the evolution of Proxima b’s water inventory. We use our spectral energy distribution to compute
the hydrogen loss from the planet with an improved energy-limited escape formalism. Despite the high level of stellar activity we find
that Proxima b is likely to have lost less than an Earth ocean’s worth of hydrogen (EOH) before it reached the HZ 100–200 Myr after
its formation. The largest uncertainty in our work is the initial water budget, which is not constrained by planet formation models. We
conclude that Proxima b is a viable candidate habitable planet.
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Artigo da revista Nature, descreve o trabalho de astrônomos para medir o tamanho e a massa de um exoplaneta parecido com Marte, além de caracterizar por completo o sistema planetário da estrela Kepler-138.
Beyond the Kuiper Belt Edge: New High Perihelion Trans-Neptunian Objects With...
We are conducting a survey for distant solar system objects beyond the Kuiper
Belt edge ( 50 AU) with new wide-field cameras on the Subaru and CTIO tele-
scopes. We are interested in the orbits of objects that are decoupled from the
giant planet region in order to understand the structure of the outer solar sys-
tem, including whether a massive planet exists beyond a few hundred AU as first
reported in Trujillo and Sheppard (2014). In addition to discovering extreme
trans-Neptunian objects detailed elsewhere, we have found several objects with
high perihelia (q > 40 AU) that differ from the extreme and inner Oort cloud
objects due to their moderate semi-major axes (50 < a < 100 AU) and eccen-
tricities (e . 0.3). Newly discovered objects 2014 FZ71 and 2015 FJ345 have
the third and fourth highest perihelia known after Sedna and 2012 VP113, yet
their orbits are not nearly as eccentric or distant. We found several of these high
perihelion but moderate orbit objects and observe that they are mostly near Nep-
tune mean motion resonances and have significant inclinations (i > 20 degrees).
These moderate objects likely obtained their unusual orbits through combined
interactions with Neptune’s mean motion resonances and the Kozai resonance,
similar to the origin scenarios for 2004 XR190. We also find the distant 2008
ST291 has likely been modified by the MMR+KR mechanism through the 6:1
Neptune resonance. We discuss these moderately eccentric, distant objects along
with some other interesting low inclination outer classical belt objects like 2012
FH84 discovered in our ongoing survey.
Exoplanets Notre Dame college (13t h MACFAIR International)
This was our team's presentation for MACFAIR International, Lucknow. Munem Shahriar Islam Shamonto was the author and I was the co-author
Jupiter
- Jupiter is the largest planet in our solar system, with a mass over 300 times that of Earth. It has 64 known moons, including the four largest called the Galilean moons - Io, Europa, Ganymede, and Callisto.
- Jupiter has intense radiation belts and a powerful magnetic field over 20,000 times stronger than Earth's. Its magnetic field traps energetic particles and creates spectacular auroras and synchrotron radiation.
- The Great Red Spot is a massive persistent storm on Jupiter twice the size of Earth that has lasted over 300 years. Jupiter's moon Io's volcanic activity feeds sulfur dioxide into Jupiter's magnetosphere, creating intense radiation belts around the planet.
Chemistry project - Space chemistry
- The document is a student's chemistry project on space chemistry. It thanks the teacher and school for allowing the project and providing resources.
- The project covers topics like the chemical composition of space, how space suits work, rocket propellants, and harnessing energy from space. It includes sections on stars and their properties, the life and death of stars, and references.
Large turbulent reservoirs of cold molecular gas around high-redshift starbur...
This document discusses observations of six lensed starburst galaxies at redshift ~2.5 using the Atacama Large Millimeter/submillimeter Array (ALMA). The key findings are:
1) ALMA detected emission and absorption lines of the CH+ molecule in the spectra of five out of the six galaxies, indicating dense shocks and highly turbulent reservoirs of cool gas extending over 10 kiloparsecs outside the starburst regions.
2) The broad CH+ emission lines trace shocks moving at ~40 km/s within dense gas, while the absorption lines reveal turbulent reservoirs with velocities of ~400 km/s.
3) The turbulent reservoirs have radii of 10-20 kilopar
Astrochemistry
Astrochemists study the chemistry of other planets and stars by working with astronomers and geologists. They analyze the chemistry of atmospheres, elemental makeup of stars and asteroids. This involves studying the chemistry and any organic compounds that may be present on other celestial bodies both near and far from Earth, including detecting organic molecules in very young galaxies over 10 billion light years away using infrared spectroscopy. A key finding is that over 90% of the mass of the human body consists of stardust from elements created in supernovas and scattered across the universe.
Protostars multiplicity and_disk_evolution_in_the_corona_australis_region
This document summarizes a study of the Corona Australis star-forming region using data from the Herschel space telescope. Key findings include:
1) Herschel maps reveal many cluster members, including some embedded very low-mass objects, several protostars (some extended), and substantial emission from the surrounding cloud.
2) Striking structures are seen, such as bright filaments around the IRS 5 protostar complex and a bubble-shaped rim associated with the Class I object IRS 2.
3) Disks around Class II objects show a wide range of properties, from massive primordial disks to disks with substantial dust depletion or evidence of inside-out evolution. This indicates a diversity of disk evolution
A rocky planet_transiting_a_nearby_low_mass_star
Um exoplaneta rochoso do tamanho da Terra, orbita uma estrela pequena e próxima, poderia ser o mundo mais importante já encontrado além do Sistema Solar, disseram os astrônomos.
O planeta localiza-se na constelação de Vela, no hemisfério sul do céu e é próximo o suficiente para que os telescópios possam observar qualquer atmosfera que ele possua, um procedimento que poderia ajudar a registrar algum tipo de vida, se ela existisse em outros planetas, no futuro.
Denominado de GJ 1132b, o exoplaneta é cerca de 16% maior que a Terra, e está localizado a cerca de 39 anos-luz de distância, o que faz com que ele seja três vezes mais próximo da Terra do que qualquer outro exoplaneta rochoso já descoberto. Nessa distância, espera-se que os telescópios sejam capazes de fazer uma análise química de sua atmosfera, a velocidade dos seus ventos e as cores do pôr-do-Sol, que acontecem no exoplaneta.
Os astrônomos registraram o planeta à medida que ele passava na frente da sua estrela, uma estrela do tipo anã vermelha, com somente um quinto do tamanho do Sol. Apesar de muito mais fria e muito mais apagada que o Sol, o GJ 1132b, tem uma órbita tão próxima da estrela que as suas temperaturas superficiais atingem cerca de 260 graus Celsius.
Essa temperatura, obviamente, é muito alta para reter a água em estado líquido na superfície do exoplaneta, fazendo com que ele seja inóspito para a vida, mas não tão quente para queimar toda uma atmosfera que pode ter se formado no planeta.
Geology of Mars
The document provides information about Mars' orbit, rotation, atmosphere and temperature. It then lists past Mars orbiters and landers/rovers. It discusses various geological features of Mars including volcanoes such as Olympus Mons, calderas, lava tubes, rift basins, and Valles Marinaris. Finally, it provides evidence that Mars once had an active hydrologic system through features such as drainage networks, springs, rivers, glaciers and oceans.
Geology of Mars
A short glimpse of geology of the planet Mars. Good for undergraduate and post-graduate students of geology, geography, earth and planetary sciences, astronomy.
The planets
The document provides information about the 8 planets and 3 dwarf planets in our solar system. It describes their key characteristics such as composition, size, orbital period, rotation period, and natural satellites. The inner planets are smaller rocky bodies, while the outer planets are large gas giants with rings. Features like impact craters, volcanoes, and storms shape the surfaces of different planets.
Active Geology on Mars
This document discusses active geological processes currently occurring on Mars. While Mars was once volcanically and sedimentarily active on a large scale, it is now considered active only on a small scale due to recent high-resolution imaging. Current small-scale processes include dust storms, dust avalanches, slope streaks caused by dry sand flows, migrating dunes, and recurring slope lineae which may indicate present liquid water. Gullies are formed by seasonal frost or dry ice sublimation and modified over time. Impacts continue to shape the surface by exposing underground ice.
A terrestrial planet_candidate_in_a_temperate_orbit_around_proxima_centauri
At a distance of 1.295 parsecs,1 the red-dwarf Proxima Centauri (α Centauri C, GL 551,
HIP 70890, or simply Proxima) is the Sun’s closest stellar neighbour and one of the best studied
low-mass stars. It has an effective temperature of only 3050 K, a luminosity of 0.1 per
cent solar, a measured radius of 0.14 R⊙
2 and a mass of about 12 per cent the mass of the
Sun. Although Proxima is considered a moderately active star, its rotation period is 83
days,3 and its quiescent activity levels and X-ray luminosity4 are comparable to the Sun’s. New
observations reveal the presence of a small planet orbiting Proxima with a minimum mass of
1.3 Earth masses and an orbital period of 11.2 days. Its orbital semi-major axis is 0.05 AU,
with an equilibrium temperature in the range where water could be liquid on its surface.5
SPECTROSCOPIC CONFIRMATION OF THE EXISTENCE OF LARGE, DIFFUSE GALAXIES IN THE...
We recently identified a population of low surface brightness objects in the field of the z = 0.023 Coma cluster,
using the Dragonfly Telephoto Array. Here we present Keck spectroscopy of one of the largest of these “ultradiffuse
galaxies” (UDGs), confirming that it is a member of the cluster. The galaxy has prominent absorption
features, including the Ca II H+K lines and the G-band, and no detected emission lines. Its radial velocity of
cz=6280±120 km s−1 is within the 1σ velocity dispersion of the Coma cluster. The galaxy has an effective
radius of 4.3 ± 0.3 kpc and a Sérsic index of 0.89 ± 0.06, as measured from Keck imaging. We find no indications
of tidal tails or other distortions, at least out to a radius of ∼2re. We show that UDGs are located in a previously
sparsely populated region of the size—magnitude plane of quiescent stellar systems, as they are ∼6 mag fainter
than normal early-type galaxies of the same size. It appears that the luminosity distribution of large quiescent
galaxies is not continuous, although this could largely be due to selection effects. Dynamical measurements are
needed to determine whether the dark matter halos of UDGs are similar to those of galaxies with the same
luminosity or to those of galaxies with the same size.
The completeness-corrected rate of stellar encounters with the Sun from the f...
I report on close encounters of stars to the Sun found in the first Gaia data release (GDR1). Combining Gaia astrometry with radial
velocities of around 320 000 stars drawn from various catalogues, I integrate orbits in a Galactic potential to identify those stars which
come within a few parsecs. Such encounters could influence the solar system, for example through gravitational perturbations of the
Oort cloud. 16 stars are found to come within 2 pc (although a few of these have dubious data). This is fewer than were found in a
similar study based on Hipparcos data, even though the present study has many more candidates. This is partly because I reject stars
with large radial velocity uncertainties (>10 km s−1
), and partly because of missing stars in GDR1 (especially at the bright end). The
closest encounter found is Gl 710, a K dwarf long-known to come close to the Sun in about 1.3 Myr. The Gaia astrometry predict
a much closer passage than pre-Gaia estimates, however: just 16 000 AU (90% confidence interval: 10 000–21 000 AU), which will
bring this star well within the Oort cloud. Using a simple model for the spatial, velocity, and luminosity distributions of stars, together
with an approximation of the observational selection function, I model the incompleteness of this Gaia-based search as a function
of the time and distance of closest approach. Applying this to a subset of the observed encounters (excluding duplicates and stars
with implausibly large velocities), I estimate the rate of stellar encounters within 5 pc averaged over the past and future 5 Myr to be
545±59 Myr−1
. Assuming a quadratic scaling of the rate within some encounter distance (which my model predicts), this corresponds
to 87 ± 9 Myr−1 within 2 pc. A more accurate analysis and assessment will be possible with future Gaia data releases.
What's hot (20)
ILOA Galaxy Forum Kansas -- Greg Novacek, Mars Exploration
ILOA Galaxy Forum Kansas -- Greg Novacek, Mars Exploration
The 19 Feb. 2016 Outburst of Comet 67P/CG: An ESA Rosetta Multi-Instrument Study
The 19 Feb. 2016 Outburst of Comet 67P/CG: An ESA Rosetta Multi-Instrument Study
The habitability of Proxima Centauri b - I. Irradiation, rotation and volatil...
The habitability of Proxima Centauri b - I. Irradiation, rotation and volatil...
The mass of_the_mars_sized_exoplanet_kepler_138_b_from_transit_timing
The mass of_the_mars_sized_exoplanet_kepler_138_b_from_transit_timing
Beyond the Kuiper Belt Edge: New High Perihelion Trans-Neptunian Objects With...
Beyond the Kuiper Belt Edge: New High Perihelion Trans-Neptunian Objects With...
Exoplanets Notre Dame college (13t h MACFAIR International)
Exoplanets Notre Dame college (13t h MACFAIR International)
Large turbulent reservoirs of cold molecular gas around high-redshift starbur...
Large turbulent reservoirs of cold molecular gas around high-redshift starbur...
Protostars multiplicity and_disk_evolution_in_the_corona_australis_region
Protostars multiplicity and_disk_evolution_in_the_corona_australis_region
A terrestrial planet_candidate_in_a_temperate_orbit_around_proxima_centauri
A terrestrial planet_candidate_in_a_temperate_orbit_around_proxima_centauri
SPECTROSCOPIC CONFIRMATION OF THE EXISTENCE OF LARGE, DIFFUSE GALAXIES IN THE...
SPECTROSCOPIC CONFIRMATION OF THE EXISTENCE OF LARGE, DIFFUSE GALAXIES IN THE...
The completeness-corrected rate of stellar encounters with the Sun from the f...
The completeness-corrected rate of stellar encounters with the Sun from the f...
Similar to Charm 050222
Titan's moon
Saturn´s Moon Titan shows many incredible features as; only liquid bodies observed in the solar other than Earth, huge seas of hydrocarbons, only moon with a thick atmosphere and also are similar to Earth in that it is dominated by nitrogen, methane and argon. Surface features consistent with erosion and however, it seems highly doubtful it is a good candidate for life.
AAS National Conference 2008: Candice Hansen
The Titan Saturn System Mission (TSSM) is a proposed joint NASA-ESA mission to conduct in-depth exploration of Titan and Enceladus. The mission would include an orbiter carrying instruments to study Titan's atmosphere, surface and interior. It would also deploy a hot air balloon and lake lander to conduct in situ measurements. The orbiter would tour Saturn's system for over 9 years, performing multiple close flybys of Titan and Enceladus to advance understanding of processes on these moons beyond what was possible with the Cassini-Huygens mission.
Enviromental chemistry ok1294987679
The document discusses the formation and evolution of Earth's atmosphere over billions of years. Isotope analysis indicates that 80-85% of the atmosphere was outgassed from the mantle within the first million years, with the remaining 15% released more slowly over time. Early gases included CO2, N2, and H2O, but oxygen only emerged around 2 billion years ago and allowed life to spread onto land. The ozone layer later developed to block harmful UV radiation.
Earth part 1
The document summarizes key aspects of Earth's habitability. It describes Earth's early history and formation, its interior structure including the solid mantle and liquid outer core that generates the magnetic field. It discusses the atmosphere, originating from outgassing and comet impacts, and how human activities like greenhouse gas emissions and CFCs are altering the atmosphere and climate.
Analysis of High Resolution Propane Spectra
This document provides background information on analyzing high resolution propane spectra and interpreting Titan's infrared spectra. It discusses:
1) Titan's atmosphere, which is dominated by nitrogen and includes trace amounts of hydrocarbons like propane.
2) Laboratory analysis of propane spectra, including characterizing spectral lines and modeling them.
3) Radiative transfer modeling to simulate how radiation interacts with molecules in Titan's atmosphere.
The analysis of propane spectra aims to better understand Titan's atmospheric composition and chemistry.
Cassini vims hyperspectral_observations_of_the_huygens _landing_site_on_titan
VIMS images of the Huygens landing site on Titan acquired during Cassini flybys in October and December 2004 provide insight into surface features near the landing site with spatial resolutions of 14.4-19 km/pixel. Ratio images of the brightest and darkest spectra in the 2.03 μm window reveal a particularly contrasted structure north of the landing site, consistent with local enrichment in exposed water ice. The images also show a possible 150 km diameter impact crater with a central peak. While scattering from haze particles dominates Titan's spectrum, spectral ratios of bright and dark areas suggest differences in surface composition and/or topography related to DISR images of the site.
Different Martian Crustal Seismic Velocities across the Dichotomy Boundary fr...
Article This article is protected by copyright. All rights reserved.
Abstract
We have observed both minor-arc (R1) and major-arc (R2) Rayleigh waves for the largest marsquake (magnitude
of 4.7 ± 0.2) ever recorded. Along the R1 path (in the lowlands), inversion results show that a simple, two-layer
model with an interface located at 21 - 29 km and an upper crustal shear-wave velocity of 3.05 - 3.17 km/s can fit the
group velocity measurements. Along the R2 path, observations can be explained by upper crustal thickness models
constrained from gravity data and upper crustal shear-wave velocities of 2.61 - 3.27 km/s and 3.28 - 3.52 km/s in the
lowlands and highlands, respectively. The shear-wave velocity being faster in the highlands than in the lowlands
indicates the possible existence of sedimentary rocks, and relatively higher porosity in the lowlands.
Ch 7 -earth
The document discusses several topics related to Earth science, including:
1) The layers of Earth's interior including the crust, mantle, and core. The mantle is partially melted lower down and rigid upper mantle.
2) Plate tectonics and how the movement of tectonic plates at a rate of 3 cm per year explains continental drift and mountain range formation.
3) The atmosphere is divided into four layers - troposphere, stratosphere, mesosphere, and thermosphere - based on temperature, composition, and density.
4) The ozone layer is an atmospheric filter that protects from UV rays, and holes in the ozone are caused by interactions with pollutant gases.
Climatology-Climatology Chapter
The document provides information about the Earth, including its formation approximately 4.5 billion years ago, composition and structure of its atmosphere, and how the atmosphere has changed over geological time through volcanic outgassing and the rise of oxygen through photosynthesis. It notes that the early Earth had a secondary atmosphere produced by volcanic outgassing rather than a primordial one, and that oxygen levels increased once cyanobacteria began producing oxygen through photosynthesis approximately 3.8 billion years ago.
interior of earth
The document discusses the interior structure of the Earth based on evidence from seismic waves, density measurements, and samples from meteorites and volcanic rocks. It describes the layers from outer to inner core:
- The crust makes up 0.5% of the Earth's mass and is divided into the continental and oceanic crust.
- The mantle lies below the crust, taking up over 80% of the Earth's mass. It is divided into the upper, lower, and outer mantle based on changes in seismic wave velocities.
- The outer core is liquid and responsible for the Earth's magnetic field through convection of molten iron.
- The solid inner core is the innermost part of the planet,
foundations of astronomy - the very basics
The document provides information about the Earth and Moon. It summarizes that the Earth is differentiated with an iron core, silicate mantle and crust. The mantle flows like a liquid due to heat convection. Plate tectonics causes geological activity. Radiometric dating indicates the Earth is approximately 4.6 billion years old. The Moon has no atmosphere or magnetic field and its surface is dominated by impact craters. Evidence suggests there may be water ice at the lunar poles.
Exocometary gas in_th_hd_181327_debris_ring
An increasing number of observations have shown that gaseous debris discs are not an
exception. However, until now we only knew of cases around A stars. Here we present the first
detection of 12CO (2-1) disc emission around an F star, HD 181327, obtained with ALMA
observations at 1.3 mm. The continuum and CO emission are resolved into an axisymmetric
disc with ring-like morphology. Using a Markov chain Monte Carlo method coupled with
radiative transfer calculations we study the dust and CO mass distribution. We find the dust is
distributed in a ring with a radius of 86:0 0:4 AU and a radial width of 23:2 1:0 AU. At
this frequency the ring radius is smaller than in the optical, revealing grain size segregation
expected due to radiation pressure. We also report on the detection of low level continuum
emission beyond the main ring out to 200 AU. We model the CO emission in the non-LTE
regime and we find that the CO is co-located with the dust, with a total CO gas mass ranging
between 1:2 10 6 M and 2:9 10 6 M, depending on the gas kinetic temperature and
collisional partners densities. The CO densities and location suggest a secondary origin, i.e.
released from icy planetesimals in the ring. We derive a CO cometary composition that is
consistent with Solar system comets. Due to the low gas densities it is unlikely that the gas is
shaping the dust distribution.
Stage astrofisica 2010- 3. Cassini e il sistema di Saturno - F.Tosi
Stage di astrofisica IASF/IFSI, 3° Edizione
Giorno 1- Lezione 3: La missione Cassini-Huygens, Il Sistema di Saturno
Martian soil as revealed by ground-penetrating radar at the Tianwen-1 landing...
Much of the Martian surface is covered by a weathering layer (regolith or soil) produced
by long-term surface processes such as impact gardening, eolian erosion, water weathering,
and glacial modifications. China’s first Martian mission, Tianwen-1, employed the Mars
Rover Penetrating Radar (RoPeR) to unveil the detailed structure of the regolith layer and
assess its loss tangent. The RoPeR radargram revealed the local regolith layer to be highly
heterogeneous and geologically complex and characterized by structures that resemble partial
or complete crater walls and near-surface impact lenses at a very shallow depth. However,
comparable radar data from the Lunar far side are rather uniform, despite the two surfaces
being geologically contemporary. The close-to-surface crater presented in this study shows
no detectable surface expression, which suggests an accelerated occultation rate for small
craters on the surface of Mars as compared to the rate on the Moon. This is probably due to
the relentless eolian processes on the Martian surface that led to the burial of the crater and
thus shielded it from further erosion. The high loss tangent indicates that the regolith at the
Tianwen-1 landing site is not dominated by water ice.
Molecular gas clumps_from_the_destruction_of_icy_bodies_in_beta_pictoris_debr...
1) ALMA observations detected carbon monoxide gas orbiting in a debris disk around the young star Beta Pictoris, with a total mass equivalent to 0.0023 times the mass of Earth's Moon.
2) The gas is distributed asymmetrically, with 30% located in a single clump 85 AU from the star. This gas clump is aligned with the orbit of an inner planet in the system.
3) The gas must be continuously replenished, likely from the destruction of icy planetesimals and comets through collisions within the debris disk. The collisions may be enhanced in the gas clump due to resonances with an unseen giant planet or from remnants of a large collision between
Molecular Gas Clumps from the Destruction of Icy Bodies in the β Pictoris Deb...
1) ALMA observations detected carbon monoxide gas orbiting in a debris disk around the young star Beta Pictoris, with a total mass equivalent to 0.0023 times the mass of Earth's Moon.
2) The gas is distributed asymmetrically, with 30% located in a single clump 85 AU from the star. This gas clump is aligned with the orbit of an inner planet in the system.
3) The gas must be continuously replenished, likely from the destruction of icy planetesimals and comets through collisions within the debris disk. The collisions may be enhanced in the gas clump due to resonances with an unseen giant planet or the remnants of a large collision between
Meteor Phenomena and Bodies
This document summarizes meteor phenomena and bodies. It discusses the different types of interactions that can occur when meteoroids collide with Earth's atmosphere, including meteors, fireballs, bolides, explosive impacts, and meteoric dust particles. It also describes the various stages of a meteoroid's trajectory through the atmosphere, including orbital motion, preheating, ablation, dark flight, and impact. Finally, it provides an overview of the size ranges and velocities associated with different meteor phenomena.
Titan’s aerosol and stratospheric ice opacities between 18 and 500 μm vertic...
This document is an accepted manuscript for publication in Icarus that summarizes research analyzing data from the Cassini CIRS instrument to characterize Titan's stratospheric aerosols and ices between 18-500 μm. The research finds that aerosols are well-mixed from the surface to 300 km altitude, while nitrile ice clouds (likely HCN and HC3N) appear centered around 90 km. There is also evidence of an ice cloud layer at 60 km that may be C2H6 ice. Volume extinction coefficients derived from CIRS data are compared to those from DISR, finding particle size ratios consistent with sub-micron aerosols and ice particle effective radii of only a few microns.
The Sol planetary system
This was completed as a training tool for a Star Trek club, and therefore contains references to Impulse- and Warp- speeds as well as Starfleet planetary classifications.
This project was also completed before Pluto's planetary status was revoked. The idea was for each presenter to learn about the solar system.
Astronomy - State of the Art - Stars
Astronomy- State of the art is a course covering the hottest topics in astronomy. In this section, the exotic end states of stars are discussed, including pulsars, neutron stars, and black holes.
Similar to Charm 050222 (20)
Cassini vims hyperspectral_observations_of_the_huygens _landing_site_on_titan
Cassini vims hyperspectral_observations_of_the_huygens _landing_site_on_titan
Different Martian Crustal Seismic Velocities across the Dichotomy Boundary fr...
Different Martian Crustal Seismic Velocities across the Dichotomy Boundary fr...
Stage astrofisica 2010- 3. Cassini e il sistema di Saturno - F.Tosi
Stage astrofisica 2010- 3. Cassini e il sistema di Saturno - F.Tosi
Martian soil as revealed by ground-penetrating radar at the Tianwen-1 landing...
Martian soil as revealed by ground-penetrating radar at the Tianwen-1 landing...
Molecular gas clumps_from_the_destruction_of_icy_bodies_in_beta_pictoris_debr...
Molecular gas clumps_from_the_destruction_of_icy_bodies_in_beta_pictoris_debr...
Molecular Gas Clumps from the Destruction of Icy Bodies in the β Pictoris Deb...
Molecular Gas Clumps from the Destruction of Icy Bodies in the β Pictoris Deb...
Titan’s aerosol and stratospheric ice opacities between 18 and 500 μm vertic...
Titan’s aerosol and stratospheric ice opacities between 18 and 500 μm vertic...
More from Sérgio Sacani
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆
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...
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...
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...
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 SEEDS
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 Universe
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 defects
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...
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 young
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...
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 ...
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.
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...
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...
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...
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...
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 Earth
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...
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.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a Technosignature
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
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A Giant Impact Origin for the First Subduction on Earth
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Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243
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Charm 050222
- 1. Titan: First Views of an Alien World Jonathan I. Lunine The University of Arizona
- 3. The three great questions: 1. Why does Titan have an atmosphere? 2. How much methane is, and has been, in the surface-atmosphere system over Titan’s history? 3. How far has organic chemistry gone on the surface of Titan?
- 5. methane ethane acetylene nitrogen HCN
- 6. ISS : high sensitivity but images of surface are affected by the haze extending from the high altitudes to the lowermost atmosphere Optical Near-IR (0.93 microns)
- 7. Credit: C. J. Lunine Credit: G. Nierenberg Haze scattering limits the information in an image…….
- 8. Credit: C. J. Lunine Credit: G. Nierenberg Haze scattering limits the information in an image…….
- 9. Each strip covers 1% of the surface at a wavelengths of a few cm’s and resolution ½-1 km. In radar images, dark is smooth or oriented away from beam; bright is rough or oriented toward the beam Radar probes the surface unaffected by the haze.
- 10. Volcanism These features are tectonic in nature, and/or might be associated with volcanism Data from Ta (October 04) Smallest features ~ 500 meters
- 11. Weaker evidence for volcanic flows in T3 data ~ 300 km
- 12. Titan—Heat flow today 6 milliWatts/m 2 Earth mean heat flow 80 milliWatts/m 2 Kargel et al., 1991
- 13. ~440 km Impact craters are seen in the most recent radar data. But the surface is still devoid of craters relative to the other Saturnian satellites. ~60 km Impacts
- 14. This portion of Tethys is roughly equal to the surface area covered by the radar on Titan pass Ta. Resolution is ~ 2 km. A direct example of cratering in the Saturn system from ISS (Titan’s dense atmosphere screens out impactors < 1 km diameter (craters < 10 km diameter). Relaxation or flooding of craters > 200 km may remove topographic clues.)
- 15. The bright plain in upper right of the T3 radar pass might be akin to the Huygens landing site But other areas look like none else—not cryovolcanic, fluvial, nor impact-related: ~200 km Longest channel ~ 200 km
- 16. PROBE RELEASE December 24, 2004 PROBE DESCENT January 14, 2005 The probe was designed only for the atmospheric descent, with the possibility of another 3-30 minutes of transmission on the surface. The probe returned over 80 minutes of data on the surface.
- 17. Complex, dendritic patterns carved by liquid methane and shaped by topography. Some of the patterns imply rainfall; others could be liquid methane liberated from subsurface. Descent Imager and Spectral Radiometer ~10 km
- 18. Huygens landed near horseshoe near lower right. Surface has a hard crust below which it is the consistency of wet sand (SSP) ~10 km
- 20. Possible history of methane degassing (consistent with isotopes of carbon, nitrogen measured by Cassini-Huygens): Tobie et al. 0 0.5 1.0 2.0 3.0 4.0 Ga Accretion + heavy bombardment Clathrate dissociation at the interface icy layer/ocean. Core overturn + Formation of an isolating MH layer + Heating of the ocean Cooling of the ocean + Formation of Ice I and HP ice layers Onset of convection Clathrate dissociation within the conductive lid Massive hot NH 3 -CH 4 atmosphere N 2 atmosphere with traces of CH 4 N 2 –CH 4 atmosphere (5-10% of CH 4 ) Escape-photolysis-condensation
- 23. Water and ammonia Atmospheric UV-driven chemistry Amino Acids Impact / volcanic melt of icy crust HCN oligomers Purines, Pyrimidines Sugars Hydrocarbons (C-H), Nitriles (H-C-N)