The Nature of Gravitational Collapse
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CHEMISTRY International October-December 2019 Volume 41 No
CHEMISTRY International The News Magazine of IUPAC October-December 2019 Volume 41 No. 4 Special IYPT2019 Elements of X INTERNATIONAL UNION OFBrought to you by | IUPAC The International Union of Pure and Applied Chemistry PURE AND APPLIED CHEMISTRY Authenticated Download Date | 11/6/19 3:09 PM Elements of IYPT2019 CHEMISTRY International he Periodic Table of Chemical Elements has without any The News Magazine of the doubt developed to one of the most significant achievements International Union of Pure and Tin natural sciences. The Table (or System, as called in some Applied Chemistry (IUPAC) languages) is capturing the essence, not only of chemistry, but also of other science areas, like physics, geology, astronomy and biology. All information regarding notes for contributors, The Periodic Table is to be seen as a very special and unique tool, subscriptions, Open Access, back volumes and which allows chemists and other scientists to predict the appear- orders is available online at www.degruyter.com/ci ance and properties of matter on earth and even in other parts of our the universe. Managing Editor: Fabienne Meyers March 1, 1869 is considered as the date of the discovery of the Periodic IUPAC, c/o Department of Chemistry Law. That day Dmitry Mendeleev completed his work on “The experi- Boston University ence of a system of elements based on their atomic weight and chemi- Metcalf Center for Science and Engineering cal similarity.” This event was preceded by a huge body of work by a 590 Commonwealth Ave. number of outstanding chemists across the world. We have elaborated Boston, MA 02215, USA on that in the January 2019 issue of Chemistry International (https:// E-mail: [email protected] bit.ly/2lHKzS5). -
CHIME and Probing the Origin of Fast Radio Bursts by Liam Dean Connor a Thesis Submitted in Conformity with the Requirements
CHIME and Probing the Origin of Fast Radio Bursts by Liam Dean Connor A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Graduate Department of Astronomy and Astrophysics University of Toronto c Copyright 2016 by Liam Dean Connor Abstract CHIME and Probing the Origin of Fast Radio Bursts Liam Dean Connor Doctor of Philosophy Graduate Department of Astronomy and Astrophysics University of Toronto 2016 The time-variable long-wavelength sky harbours a number of known but unsolved astro- physical problems, and surely many more undiscovered phenomena. With modern tools such problems will become tractable, and new classes of astronomical objects will be revealed. These tools include digital telescopes made from powerful computing clusters, and improved theoretical methods. In this thesis we employ such devices to understand better several puzzles in the time-domain radio sky. Our primary focus is on the origin of fast radio bursts (FRBs), a new class of transients of which there seem to be thousands per sky per day. We offer a model in which FRBs are extragalactic but non-cosmological pulsars in young supernova remnants. Since this theoretical work was done, observations have corroborated the picture of FRBs as young rotating neutron stars, including the non-Poissonian repetition of FRB 121102. We also present statistical arguments regard- ing the nature and location of FRBs. These include reinstituting the classic V=Vmax-test @ log N to measure the brightness distribution of FRBs, i.e., constraining @ log S . We find consis- tency with a Euclidean distribution. This means current observations cannot distinguish between a cosmological population and a more local uniform population, unless added assumptions are made. -
Neutron Stars & Black Holes
Introduction ? Recall that White Dwarfs are the second most common type of star. ? They are the remains of medium-sized stars - hydrogen fused to helium Neutron Stars - failed to ignite carbon - drove away their envelopes to from planetary nebulae & - collapsed and cooled to form White Dwarfs ? The more massive a White Dwarf, the smaller its radius Black Holes ? Stars more massive than the Chandrasekhar limit of 1.4 solar masses cannot be White Dwarfs Formation of Neutron Stars As the core of a massive star (residual mass greater than 1.4 ?Supernova 1987A solar masses) begins to collapse: (arrow) in the Large - density quickly reaches that of a white dwarf Magellanic Cloud was - but weight is too great to be supported by degenerate the first supernova electrons visible to the naked eye - collapse of core continues; atomic nuclei are broken apart since 1604. by gamma rays - Almost instantaneously, the increasing density forces freed electrons to absorb electrons to form neutrons - the star blasts away in a supernova explosion leaving behind a neutron star. Properties of Neutron Stars Crab Nebula ? Neutrons stars predicted to have a radius of about 10 km ? In CE 1054, Chinese and a density of 1014 g/cm3 . astronomers saw a ? This density is about the same as the nucleus supernova ? A sugar-cube-sized lump of this material would weigh 100 ? Pulsar is at center (arrow) million tons ? It is very energetic; pulses ? The mass of a neutron star cannot be more than 2-3 solar are detectable at visual masses wavelengths ? Neutron stars are predicted to rotate very fast, to be very ? Inset image taken by hot, and have a strong magnetic field. -
Study of Pulsar Wind Nebulae in Very-High-Energy Gamma-Rays with H.E.S.S
Study of Pulsar Wind Nebulae in Very-High-Energy gamma-rays with H.E.S.S. Michelle Tsirou To cite this version: Michelle Tsirou. Study of Pulsar Wind Nebulae in Very-High-Energy gamma-rays with H.E.S.S.. As- trophysics [astro-ph]. Université Montpellier, 2019. English. NNT : 2019MONTS096. tel-02493959 HAL Id: tel-02493959 https://tel.archives-ouvertes.fr/tel-02493959 Submitted on 28 Feb 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. THÈSE POUR OBTENIR LE GRADE DE DOCTEUR DE L’UNIVERSITÉ DE MONTPELLIER En Astrophysiques École doctorale I2S Unité de recherche UMR 5299 Study of Pulsar Wind Nebulae in Very-High-Energy gamma-rays with H.E.S.S. Présentée par Michelle TSIROU Le 17 octobre 2019 Sous la direction de Yves A. GALLANT Devant le jury composé de Elena AMATO, Chercheur, INAF - Acetri Rapporteur Arache DJANNATI-ATAȈ, Directeur de recherche, APC - Paris Examinateur Yves GALLANT, Directeur de recherche, LUPM - Montpellier Directeur de thèse Marianne LEMOINE-GOUMARD, Chargée de recherche, CENBG - Bordeaux Rapporteur Alexandre MARCOWITH, Directeur de recherche, LUPM - Montpellier Président du jury Study of Pulsar Wind Nebulae in Very-High-Energy gamma-rays with H.E.S.S.1 Michelle Tsirou 1High Energy Stereoscopic System To my former and subsequent selves, may this wrenched duality amalgamate ultimately. -
The Planck Mass and the Chandrasekhar Limit
The Planck mass and the Chandrasekhar limit ͒ David Garfinklea Department of Physics, Oakland University, Rochester, Michigan 48309 ͑Received 6 November 2008; accepted 10 March 2009͒ The Planck mass is often assumed to play a role only at the extremely high energy scales where quantum gravity becomes important. However, this mass plays a role in any physical system that involves gravity, quantum mechanics, and relativity. We examine the role of the Planck mass in determining the maximum mass of white dwarf stars. © 2009 American Association of Physics Teachers. ͓DOI: 10.1119/1.3110884͔ I. INTRODUCTION ery part of the gas is in equilibrium and thus must have zero net force on it. In particular, consider a small disk of the gas The Planck mass, length, and time can be constructed with base area A and thickness dr at a distance r from the from the Newton gravitational constant G, the Planck con- center of the ball. Denote the mass of the disk by m , and the ប 1 d stant , and the speed of light c. In particular, the Planck mass of all the gas at radii smaller than r by M͑r͒. Newton mass, MP is given by showed that the disk would be gravitationally attracted by បc the gas at radii smaller than r, but unaffected by the gas at M = ͱ . ͑1͒ radii larger than r, and the force on the disk would be the P G same as if all the mass at radii smaller than r were concen- The Planck mass is very small on the human scale because trated at the center. -
The MSU Project Lomonosov
D.V. Skobeltsyn Institute of Nuclear Physics of M.V. Lomonosov Moscow State University (SINP) 4. Information about Scientific Projects of the Federal Space Program of the Russian Federation with are at the Development (Working out) Stage The MSU project Lomonosov There are three basic goals of the Lomonosov experiment: • ultra-high energy cosmic rays (UHECR) studies; • gamma-bursts registration and observations in multi-spectral mode; • complex monitoring of the near-Earth space. These problems are at the frontier of the current space research. Calculated parameters of the spacecraft's orbit: • altitude 490 ± 10 km; • inclination 98 о; • local time ascending node (local time of the spacecraft) 11:15. Expected active life of the spacecraft is 3 years. The basic scientific purposes of the scientific equipment of Lomonosov spacecraft are the following: 1) Adjustment of the methods of UHECR registration from space by fluorescent method, measurements of UV background of the neigt atmosphere. 2) Registration of UHECR events near Greizen-Zatsepin-Kuzmin cut-off, measurements of UHECR particles energy and coming direction. 1 3) Measurements of UV bursts, associated with thunderstorms, in the Earth's atmosphere (so-called transient atmospheric phenomena – sprites, blue jets, elves, etc.). 4) Registration of gamma-bursts within wide wave range – from optical and UV to X-ray and gamma. 5) Real-time transmission of the coordinates of gamma-burst to the ground- based telescope network (GCN) in order to guide them to the event. 6) Registration of moving objects in the upper hemisphere of the spacecraft, including small asteroids and space debris. 7) Experimental determination of the total radiation danger (both from charged and neutral particles) during the flight along the polar orbit by means of dosimetry equipment, developed for this purpose. -
Lecture 15: Stars
Matthew Schwartz Statistical Mechanics, Spring 2019 Lecture 15: Stars 1 Introduction There are at least 100 billion stars in the Milky Way. Not everything in the night sky is a star there are also planets and moons as well as nebula (cloudy objects including distant galaxies, clusters of stars, and regions of gas) but it's mostly stars. These stars are almost all just points with no apparent angular size even when zoomed in with our best telescopes. An exception is Betelgeuse (Orion's shoulder). Betelgeuse is a red supergiant 1000 times wider than the sun. Even it only has an angular size of 50 milliarcseconds: the size of an ant on the Prudential Building as seen from Harvard square. So stars are basically points and everything we know about them experimentally comes from measuring light coming in from those points. Since stars are pointlike, there is not too much we can determine about them from direct measurement. Stars are hot and emit light consistent with a blackbody spectrum from which we can extract their surface temperature Ts. We can also measure how bright the star is, as viewed from earth . For many stars (but not all), we can also gure out how far away they are by a variety of means, such as parallax measurements.1 Correcting the brightness as viewed from earth by the distance gives the intrinsic luminosity, L, which is the same as the power emitted in photons by the star. We cannot easily measure the mass of a star in isolation. However, stars often come close enough to another star that they orbit each other. -
1549504043838.Pdf
AUTHOR ELH COVER ART Martin Sobr SPECIAL THANKS TO MY PATREON BACKERS Brian Sanderz, Doug H, Spencer Morgan, Kalik Long, Soup, Ge Tz, cn, VERSION & LAST UPDATED v1.0 – February 6th, 2019 You can find ELH on: This content is available free of charge and licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License Neither the author (ELH) nor the content within is endorsed, sponsored, or affiliated with CBS Studios Inc., Paramount Pictures, Modiphius Entertainment, or the STAR TREK franchise. The Star Trek® franchise and related logos are owned and a registered trademark of Paramount Pictures & CBS Studios Inc. 2 | P a g e Table of Contents Introduction .................................................................................................................................................. 4 Andromeda ................................................................................................................................................... 6 Heart of Steel ................................................................................................................................................ 9 New Neighborhood ..................................................................................................................................... 16 Paradox ....................................................................................................................................................... 23 Muuat ......................................................................................................................................................... -
Compact Stars and the Evolution of Binary Systems
Bull. Astr. Soc. India (2011) 39, 1–20 Compact stars and the evolution of binary systems E. P. J. van den Heuvel Astronomical Institute, “Anton Pannekoek”, University of Amsterdam, The Netherlands Received 2011 January 31; accepted 2011 February 27 Abstract. The Chandrasekhar limit is of key importance for the evolution of white dwarfs in binary systems and for the formation of neutron stars and black holes in bi- naries. Mass transfer can drive a white dwarf in a binary over the Chandrasekhar limit, which may lead to a Type Ia supernova (in case of a CO white dwarf) or an Accretion- Induced Collapse (AIC, in the case of an O-Ne-Mg white dwarf; and possibly also in some CO white dwarfs) which produces a neutron star. The direct formation of neu- tron stars or black holes out of degenerate stellar cores that exceed the Chandrasekhar limit, occurs in binaries with components that started out with masses ¸ 8 M¯. This paper first discusses possible models for Type Ia supernovae, and then focusses on the formation of neutron stars in binary systems, by direct core collapse and by the AIC of O-Ne-Mg white dwarfs in binaries. Observational evidence is re- viewed for the existence of two different direct neutron-star formation mechanisms in binaries: (i) by electron-capture collapse of the degenerate O-Ne-Mg core in stars with initial masses in the range of 8 to about 12 M¯, and (ii) by iron-core collapse in stars with inital masses above this range. Observations of neutron stars in binaries are consistent with a picture in which neutron stars produced by e-capture collapse have relatively low masses, »1.25 M¯, and received hardly any velocity kick at birth, whereas neutron stars produced by iron-core collapses are more massive and received large velocity kicks at birth. -
Fermi Questions: [email protected] Answers from November
Larry Weinstein, Column Editor Old Dominion University, Norfolk, VA 23529; Fermi Questions: [email protected] Answers from November 10 Question 1, Neutron Stars: The Sun rotates on angular velocity must increase by 10 . This its axis once per month. If the Sun shrinks and becomes means that its period will decrease by 1010. Let’s a neutron star, by what factor will its rotational inertia express a month in SI units. 1 month = 30 days ϫ change? What will its new period of rotation be? (Note: 24 hr/day ϫ 60 min/hr ϫ 60 s/min ≈ 3 ϫ 106 s. the density of the Sun today is approximately Thus, the Sun’s new period will be T = 3 ϫ 106 s/ 103 kg/m3.) 1010 = 3 ϫ 10-4 s. Answer: First we need to know the density of a neutron star. To do that we need to estimate the Note that this method significantly overesti- density of neutronium. We can estimate the den- mates the change in rotational inertia because sity of neutronium in a few ways. If you know we assumed a uniform density. This is a good the size of the typical nucleus, you can extrapolate assumption for a neutron star but a very bad from that (remembering that 99.9% of the mass assumption for the Sun. Taking this into account of the atom is in the nucleus). The nucleus of lead properly should increase the neutron star period has a radius of 6 10-15 m so that its density is significantly. Copyright 2007, Lawrence Weinstein ρ = 0. -
Highly Magnetized Super-Chandrasekhar White Dwarfs and Their Consequences
Contrib. Astron. Obs. Skalnat´ePleso 48, 250–258, (2018) Highly magnetized super-Chandrasekhar white dwarfs and their consequences B. Mukhopadhyay1, U. Das2 and A.R.Rao3 1 Indian Institute of Science, Bangalore, India, (E-mail: [email protected]) 2 University of Colorado, Boulder, USA 3 Tata Institute of Fundamental Research, Mumbai, India Received: November 17, 2017; Accepted: November 22, 2017 Abstract. Since 2012, we have been exploring possible existence of highly magnetized significantly super-Chandrasekhar white dwarfs with a new mass- limit. This explains several observations, e.g. peculiar over-luminous type Ia supernovae, some white dwarf pulsars, soft gamma-ray repeaters and anoma- lous X-ray pulsars, which otherwise puzzled us enormously. We have proceeded to uncover the underlying issues by exploiting the enormous potential in quan- tum, classical and relativistic effects lying with magnetic fields present in white dwarfs. We have also explored the issues related to the stability and gravita- tional radiation of these white dwarfs. Key words: white dwarfs – supernovae: general – stars: magnetic fields – pulsars: general – gravitation – x-rays: general 1. Introduction In the last five years or so, we have initiated modeling highly magnetized super- Chandrasekhar white dwarfs (B-WDs). We initiated our exploration by consid- ering a simplistic spherically symmetric Newtonian model to study the quantum mechanical effects of a strong magnetic field on the composition of the white dwarf (Das & Mukhopadhyay, 2012). This in turn led to the discovery of a new mass-limit significantly larger than the Chandrasekhar limit (Das & Mukhopad- hyay, 2013), thus heralding the onset of a paradigm shift. -
Mass-To-Energy Conversion, the Astrophysical Mechanism
Journal of High Energy Physics, Gravitation and Cosmology, 2019, 5, 520-551 http://www.scirp.org/journal/jhepgc ISSN Online: 2380-4335 ISSN Print: 2380-4327 Mass-to-Energy Conversion, the Astrophysical Mechanism Conrad Ranzan Astrophysics Deptarment, DSSU Research, Niagara Falls, Canada How to cite this paper: Ranzan, C. (2019) Abstract Mass-to-Energy Conversion, the Astro- physical Mechanism. Journal of High A new interpretation of the relativistic equation relating total-, momentum-, and Energy Physics, Gravitation and Cosmolo- mass-energies is presented. With the aid of the familiar energy-relationship gy, 5, 520-551. triangle, old and new interpretations are compared. And the key difference is https://doi.org/10.4236/jhepgc.2019.52030 emphasized—apparent relativity versus intrinsic relativity. Mass-to-energy Received: March 14, 2019 conversion is then brought about by adopting a three-part strategy: 1) Make Accepted: April 26, 2019 the motion relative to the universal space medium. This allows the introduc- Published: April 29, 2019 tion of the concept of intrinsic energy (total, kinetic, and mass energies) as counterpart to the apparent version. 2) Recognize that a particle’s mass prop- Copyright © 2019 by author(s) and erty diminishes with increase in speed. This means introducing the concept of Scientific Research Publishing Inc. This work is licensed under the Creative intrinsic mass (which varies with intrinsic speed). 3) Impose a change in the Commons Attribution International particle’s gravitational environment. Instead of applying an electromagnetic License (CC BY 4.0). accelerating force or energy in order to alter the particle’s total energy, there http://creativecommons.org/licenses/by/4.0/ will simply be an environmental change.