Pulsars
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Pulsars are rapidly rotating neutron stars that emit beams of electromagnetic radiation. They act as "lighthouses" that sweep through space as they spin. The first pulsar was discovered in 1967 and emitted pulses every 1.33 seconds. Pulsars form when massive stars undergo supernova explosions, collapsing the star into an ultra-dense neutron core. Their strong magnetic fields and rapid rotation produce beams of radiation detectable from Earth. Around 1600 pulsars have been discovered with properties like the Crab pulsar's 33 millisecond period.
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Introduction to Pulsar(Astrophysics)
This document discusses pulsars and provides information about them. It begins by listing the group members and topics to be discussed, including an introduction to pulsars, their properties, discovery, formation from neutron stars, examples of the Crab pulsar and binary pulsars, and their radiating mechanism. It then provides details on the properties of pulsars, their extremely high density, classification, and the discovery of the first pulsar PSR B1919+21. The document summarizes how pulsars are formed from the collapse and rotation of massive stars, and discusses the Crab pulsar and binary pulsars in more detail. It concludes by outlining some applications and milestones of pulsar research, including their use in gravitational wave
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Neutron stars are extremely dense remnants of dead stars approximately 4-8 times the mass of the Sun that have collapsed into a city-sized object composed almost entirely of neutrons. They form when a massive star runs out of fuel and collapses under its own gravity, compressing its core into neutrons. Neutron stars can spin hundreds of times per second and have immense gravitational pulls billions of times stronger than Earth. They emit radiation known as pulsars and have some of the strongest magnetic fields in the universe. Neutron stars can survive for billions of years as they slowly cool.
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Binary stars are two stars orbiting a common center of mass, with the brighter star classified as the primary and dimmer as the secondary. Galileo first observed binary stars in 1617 when he noticed one star seemed to be two. Binary stars can form when a massive star captures a passing star. There are four main classifications of binary stars: visual binaries which can be seen separately through a telescope; spectroscopic binaries which appear close but can't be resolved; eclipsing binaries whose orbits cause one star to pass in front of the other; and astrometric binaries where the companion star can only be inferred.
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Stars are formed from the collapse of giant clouds of dust and gas in space. As the cloud collapses due to gravity, it heats up and eventually nuclear fusion begins in its core, forming a new star. Stars exist in different colors and sizes depending on their mass, with more massive stars being hotter, brighter, and having shorter lifespans than less massive stars. Eventually a star runs out of hydrogen fuel for fusion in its core, causing it to expand into a red giant and later die, leaving behind a white dwarf, neutron star, or black hole depending on its original mass.
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A presentation I gave to the Brighton Astronomy Society in Jan 2016 - http://brightonastro.com/ , https://www.facebook.com/brightonastro/
Annoyingly that's removed the videos from the slides, so here are links to those:
https://www.youtube.com/watch?v=e-P5IFTqB98&t=18s
(This Youtube channel "In a nutshell" is absolutely fantastic by the way and I highly recommend a look through their other videos!)
https://www.youtube.com/watch?v=duoHtJpo4GY
https://vimeo.com/8723702
I've also made my notes from preparing the slides available here as well:
https://docs.google.com/document/d/1gqgsAbvoCB_7-_gPToqOuSixc02YnU-ajf-uT60R1vc/edit?usp=sharing
-- there are LOTS of further links to interesting videos in there as well, that I didn't use on the night so worth a scan through.
Any further questions, feel free to ask in comments on here
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The Sun is a typical star composed primarily of hydrogen and helium gases. It has a core temperature of 15 million K that fuels nuclear fusion reactions. Energy is transferred from the core through radiation and convection zones to the photosphere. Above the photosphere are the chromosphere and transition region, and the outer corona extends far out into space propelling the solar wind. Observation across electromagnetic wavelengths provides insights into the Sun's interior structure and dynamic atmosphere.
Space weather and potential impact on earth’s climate dec 19 10 v2
This document discusses space weather and its potential impacts on Earth's climate and seismic activity. It provides an overview of the solar system and its dynamics, as well as how our solar system interacts with the Milky Way galaxy and larger universe. Recent observations have found evidence that the outer boundaries of our solar system are being compressed as we pass through Galactic clouds, allowing more cosmic rays and energetic particles to enter the inner solar system. This could affect Earth's climate and increase seismic activity. The document also discusses changes observed on other planets in our solar system, such as the growth of dark spots on Pluto and changes in cloud cover on Mars.
MasersPresentation (1).ppt
- A maser is a device that amplifies microwaves through stimulated emission of radiation, causing electrons in excited molecules to release photons that add up coherently (in phase).
- The first ammonia maser was developed in 1953, and the first hydrogen maser used today was created by Norman Ramsey in 1960. Natural masers have been detected in space since 1965.
- Maser molecules include atomic hydrogen and ammonia, gaseous rubidium, solid-state ruby, dual noble gases, and liquid water. Laboratory masers are more powerful than natural ones.
- Hydrogen masers are used in atomic clocks for timekeeping. Astrophysical masers identify conditions
Neutron star ,an interesting part of astronomy.
A small work about neutron star which will make you interest in astrophysics ,a fascinating things on this earth.Moreover you will learn some facts about astronomy.
Apes earth systems
The document summarizes the origins and evolution of the universe, galaxy, solar system, and Earth. It begins by explaining how the Big Bang occurred approximately 13.7 billion years ago, marking the expansion of the early universe. It then describes how the universe cooled and formed elemental structures, galaxies, stars, and planets over billions of years. Specific details are provided about the formation of the Milky Way galaxy and solar system, including Earth. The geological history of Earth is outlined, dividing time into eons, eras, periods, and epochs marked by significant evolutionary changes and extinctions.
Astronomy - State of the Art - Galaxies
Astronomy - State of the Art is a course covering the hottest topics in astronomy. In this section, the properties of galaxies are discussed, including supermassive black holes and dark matter.
Physics of atom
This document discusses the physics of atoms and their subatomic particles. It describes the Bohr model of the atom, which depicts electrons orbiting the nucleus in fixed orbits or shells. When electrons move between these shells, energy is absorbed or emitted in the form of radiation. The document also outlines the discoveries of subatomic particles like electrons, protons, and neutrons through experiments such as Rutherford's gold foil experiment and Chadwick's work. Finally, it provides the names, symbols, masses, and charges of the basic particles that make up an atom: protons, neutrons, and electrons.
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Authoring a personal GPT for your research and practice: How we created the Q...
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
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.
BIRDS DIVERSITY OF SOOTEA BISWANATH ASSAM.ppt.pptx
Ahota Beel, nestled in Sootea Biswanath Assam , is celebrated for its extraordinary diversity of bird species. This wetland sanctuary supports a myriad of avian residents and migrants alike. Visitors can admire the elegant flights of migratory species such as the Northern Pintail and Eurasian Wigeon, alongside resident birds including the Asian Openbill and Pheasant-tailed Jacana. With its tranquil scenery and varied habitats, Ahota Beel offers a perfect haven for birdwatchers to appreciate and study the vibrant birdlife that thrives in this natural refuge.
fermented food science of sauerkraut.pptx
This ppt contains the production of a fermented food name - sauerkraut
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.
The cost of acquiring information by natural selection
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
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
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Randomised Optimisation Algorithms in DAPHNE
Slides from talk:
Aleš Zamuda: Randomised Optimisation Algorithms in DAPHNE .
Austrian-Slovenian HPC Meeting 2024 – ASHPC24, Seeblickhotel Grundlsee in Austria, 10–13 June 2024
https://ashpc.eu/
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
Farming systems analysis: what have we learnt?.pptx
Presentation given at the official farewell of Prof Ken Gillet at Wageningen on 13 June 2024
Direct Seeded Rice - Climate Smart Agriculture
Direct Seeded Rice - Climate Smart AgricultureInternational Food Policy Research Institute- South Asia Office
PPT on Direct Seeded Rice presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
HUMAN EYE By-R.M Class 10 phy best digital notes.pdf
Class 10 human eye notes physics
Handwritten best quality
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...
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Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.Recently uploaded (20)
Authoring a personal GPT for your research and practice: How we created the Q...
Authoring a personal GPT for your research and practice: How we created the Q...
Anti-Universe And Emergent Gravity and the Dark Universe
Anti-Universe And Emergent Gravity and the Dark Universe
BIRDS DIVERSITY OF SOOTEA BISWANATH ASSAM.ppt.pptx
BIRDS DIVERSITY OF SOOTEA BISWANATH ASSAM.ppt.pptx
The cost of acquiring information by natural selection
The cost of acquiring information by natural selection
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...
Farming systems analysis: what have we learnt?.pptx
Farming systems analysis: what have we learnt?.pptx
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...
HUMAN EYE By-R.M Class 10 phy best digital notes.pdf
HUMAN EYE By-R.M Class 10 phy best digital notes.pdf
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...
Juaristi, Jon. - El canon espanol. El legado de la cultura española a la civi...
Juaristi, Jon. - El canon espanol. El legado de la cultura española a la civi...
Pulsars
- 2. The Light House of the Universe PULSARS
- 3. WHAT ARE PULSARS? • “Lighthouses of the Universe” • Special kind of neutron star • Emits beam of gamma rays, x rays, or radio waves which sweeps through Earth’s line of sight; pulsating effect • Spins up to several 100 times a second • Have highly intense magnetic and electric field (several trillion Gauss and Volts)
- 4. DISCOVERY • First one discovered by Cambridge University Researchers Jocelyn Bell and Antony Hewish in 1967 • Detected pulses separated by 1.33 seconds from same position in the sky • Second pulsar was discovered in the Crab Nebula with a period of 33 milliseconds; confirmed it was a rotating a neutron star • Around 1600 pulsars found
- 5. FORMATION • Stars having 8 to 25 times mass of sun initially • At end of life undergoes supernova explosion (outer layers burst out) • Electrons and protons are crushed together to form neutron core • collapses into neutron star without collapsing into black hole • 1.4 to 3.2 times mass of sun • About 20 kilometres in diameter and extremely high density
- 6. STRUCTURE AND MECHANISM • When star collapses into a neutron star radius is dramatically decreased to fraction of original star; very high speed • As mass moves closer to centre of mass rotational speed increases • Produces strong magnetic field • Magnetic axis and rotational axis not aligned
- 7. • Combination of strong magnetic field and rapid rotation produces powerful electric field • Electric field accelerates electrons • High energy electrons produce radiations By acting as plasma to produce radiation By interacting with photons or magnetic field • Point of emission of radiation is somewhere around magnetic poles • When beam around magnetic poles is in earth’s line of sight, radiation is detected • Lighthouse effect
- 8. STRUCTURE AND MECHANISM • rotation slows down over time as electromagnetic power is emitted • When a pulsar's spin period slows down sufficiently, the radio pulsar mechanism turns off
- 9. HOW WE DETECT PULSARS • When rotating pulse is pointed towards earth, signal is detected (mainly as x ray, gamma or radiowaves by spectroscopic methods) • When pointed away signal fades • Appear as pulses at very regular intervals
- 10. ACCRETION POWERED PULSARS • Binary System of pulsar and companion star • Gas from companion gets pulled in or “accreted” to magnetic polar caps (gravity) • Mass transfer increases speed of rotation tremendously • Converts them into millisecond pulsars
- 11. • CRAB PULSAR Situated in Crab Nebula Second Pulsar discovered Has period 33 milliseconds Forms major portion of emissions from the Crab Nebula IMPORTANT PULSARS A slow-motion movie of the Crab Pulsar taken at 800 nm wavelength (near- infrared) using a Lucky Imaging camera from Cambridge University, showing the bright pulse and fainter interpulse
- 12. • VELA PULSAR Spins 11.195 times per second Emits radio, optical and gamma rays Brightest known object in gamma ray sky Cycle of pulsed gamma rays from Vela Pulsar
- 13. • PSR J0108-1431 Oldest Pulsar known (200 million years old) Only 770 LY from earth
- 14. • PSR J1823−3021A Youngest millisecond pulsar yet observed (25 million years old) Fastest pulsar yet observed 183.8 times per second Detected in NGC 6624 (spherical cluster of ancient stars)
- 15. APPLICATIONS • Maps and Navigation – pulsar position to create a spacecraft navigation system; eg. Sun’s position relative to 14 pulsars mapped out; identified by unique periods • Precise Clocks – very regular period, more accurate than atomic clocks • To Test theories of Gravity – strong gravitational force
- 16. THANK YOU