Kasliwal Phd Thesis
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PHYS 633: Introduction to Stellar Astrophysics Spring Semester 2006 Rich Townsend ([email protected])
PHYS 633: Introduction to Stellar Astrophysics Spring Semester 2006 Rich Townsend ([email protected]) Governing Equations In the foregoing analysis, we have seen how a star usually maintains a state of hydrostatic equilibrium. We have seen how the energy created in the star through nuclear reactions, or released through contraction, makes its way out in the form of the star’s luminosity. We have seen how the physical processes responsible for transporting this energy can either be radiation or convection. And, finally, we have seen how nuclear reactions within the star, and transport processes such as convective mixing, can alter the stars chemical composition. These four key pieces of physics lead to 3 + I of the differential equations governing stellar structure (here, I is the number of elements whose evolution we are following). Let’s quickly review these equations. First, we have the most general (spherically-symmetric) form for the equation governing momen- tum conservation, ∂P Gm 1 ∂2r = − − . (1) ∂m 4πr2 4πr2 ∂t2 If the second term on the right-hand side vanishes, then we recover the equation of hydrostatic equilibrium, expressed in Lagrangian form (i.e., derivatives with respect to the mass coordinate m, rather than the radial coordinate r). If this term does not vanish at some point in the star, then the mass shells at that point will being to expand or contract, with an acceleration given by ∂2r/∂t2. Second, we have the most general form for the energy conservation equation, ∂l ∂T δ ∂P = − − c + . (2) ∂m ν P ∂t ρ ∂t The first and second terms on the right-hand side come from nuclear energy gen- eration and neutrino losses, respectively. -
Used Time Scales GEORGE E
PROCEEDINGS OF THE IEEE, VOL. 55, NO. 6, JIJNE 1967 815 Reprinted from the PROCEEDINGS OF THE IEEI< VOL. 55, NO. 6, JUNE, 1967 pp. 815-821 COPYRIGHT @ 1967-THE INSTITCJTE OF kECTRITAT. AND ELECTRONICSEN~INEERS. INr I’KINTED IN THE lT.S.A. Some Characteristics of Commonly Used Time Scales GEORGE E. HUDSON A bstract-Various examples of ideally defined time scales are given. Bureau of Standards to realize one international unit of Realizations of these scales occur with the construction and maintenance of time [2]. As noted in the next section, it realizes the atomic various clocks, and in the broadcast dissemination of the scale information. Atomic and universal time scales disseminated via standard frequency and time scale, AT (or A), with a definite initial epoch. This clock time-signal broadcasts are compared. There is a discussion of some studies is based on the NBS frequency standard, a cesium beam of the associated problems suggested by the International Radio Consultative device [3]. This is the atomic standard to which the non- Committee (CCIR). offset carrier frequency signals and time intervals emitted from NBS radio station WWVB are referenced ; neverthe- I. INTRODUCTION less, the time scale SA (stepped atomic), used in these emis- PECIFIC PROBLEMS noted in this paper range from sions, is only piecewise uniform with respect to AT, and mathematical investigations of the properties of in- piecewise continuous in order that it may approximate to dividual time scales and the formation of a composite s the slightly variable scale known as UT2. SA is described scale from many independent ones, through statistical in Section 11-A-2). -
14 Timescales in Stellar Interiors
14Timescales inStellarInteriors Having dealt with the stellar photosphere and the radiation transport so rel- evant to our observations of this region, we’re now ready to journey deeper into the inner layers of our stellar onion. Fundamentally, the aim we will de- velop in the coming chapters is to develop a connection betweenM,R,L, and T in stars (see Table 14 for some relevant scales). More specifically, our goal will be to develop equilibrium models that describe stellar structure:P (r),ρ (r), andT (r). We will have to model grav- ity, pressure balance, energy transport, and energy generation to get every- thing right. We will follow a fairly simple path, assuming spherical symmetric throughout and ignoring effects due to rotation, magneticfields, etc. Before laying out the equations, let’sfirst think about some key timescales. By quantifying these timescales and assuming stars are in at least short-term equilibrium, we will be better-equipped to understand the relevant processes and to identify just what stellar equilibrium means. 14.1 Photon collisions with matter This sets the timescale for radiation and matter to reach equilibrium. It de- pends on the mean free path of photons through the gas, 1 (227) �= nσ So by dimensional analysis, � (228)τ γ ≈ c If we use numbers roughly appropriate for the average Sun (assuming full Table3: Relevant stellar quantities. Quantity Value in Sun Range in other stars M2 1033 g 0.08 �( M/M )� 100 × � R7 1010 cm 0.08 �( R/R )� 1000 × 33 1 3 � 6 L4 10 erg s− 10− �( L/L )� 10 × � Teff 5777K 3000K �( Teff/mathrmK)� 50,000K 3 3 ρc 150 g cm− 10 �( ρc/g cm− )� 1000 T 1.5 107 K 106 ( T /K) 108 c × � c � 83 14.Timescales inStellarInteriors P dA dr ρ r P+dP g Mr Figure 28: The state of hydrostatic equilibrium in an object like a star occurs when the inward force of gravity is balanced by an outward pressure gradient. -
Stellar Structure and Evolution
Lecture Notes on Stellar Structure and Evolution Jørgen Christensen-Dalsgaard Institut for Fysik og Astronomi, Aarhus Universitet Sixth Edition Fourth Printing March 2008 ii Preface The present notes grew out of an introductory course in stellar evolution which I have given for several years to third-year undergraduate students in physics at the University of Aarhus. The goal of the course and the notes is to show how many aspects of stellar evolution can be understood relatively simply in terms of basic physics. Apart from the intrinsic interest of the topic, the value of such a course is that it provides an illustration (within the syllabus in Aarhus, almost the first illustration) of the application of physics to “the real world” outside the laboratory. I am grateful to the students who have followed the course over the years, and to my colleague J. Madsen who has taken part in giving it, for their comments and advice; indeed, their insistent urging that I replace by a more coherent set of notes the textbook, supplemented by extensive commentary and additional notes, which was originally used in the course, is directly responsible for the existence of these notes. Additional input was provided by the students who suffered through the first edition of the notes in the Autumn of 1990. I hope that this will be a continuing process; further comments, corrections and suggestions for improvements are most welcome. I thank N. Grevesse for providing the data in Figure 14.1, and P. E. Nissen for helpful suggestions for other figures, as well as for reading and commenting on an early version of the manuscript. -
UC Irvine UC Irvine Previously Published Works
UC Irvine UC Irvine Previously Published Works Title Astrophysics in 2006 Permalink https://escholarship.org/uc/item/5760h9v8 Journal Space Science Reviews, 132(1) ISSN 0038-6308 Authors Trimble, V Aschwanden, MJ Hansen, CJ Publication Date 2007-09-01 DOI 10.1007/s11214-007-9224-0 License https://creativecommons.org/licenses/by/4.0/ 4.0 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Space Sci Rev (2007) 132: 1–182 DOI 10.1007/s11214-007-9224-0 Astrophysics in 2006 Virginia Trimble · Markus J. Aschwanden · Carl J. Hansen Received: 11 May 2007 / Accepted: 24 May 2007 / Published online: 23 October 2007 © Springer Science+Business Media B.V. 2007 Abstract The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006. We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the Universe) and others of which there are always many, like meteors and molecules, black holes and binaries. Keywords Cosmology: general · Galaxies: general · ISM: general · Stars: general · Sun: general · Planets and satellites: general · Astrobiology · Star clusters · Binary stars · Clusters of galaxies · Gamma-ray bursts · Milky Way · Earth · Active galaxies · Supernovae 1 Introduction Astrophysics in 2006 modifies a long tradition by moving to a new journal, which you hold in your (real or virtual) hands. The fifteen previous articles in the series are referenced oc- casionally as Ap91 to Ap05 below and appeared in volumes 104–118 of Publications of V. -
Modeling and Interpretation of the Ultraviolet Spectral Energy Distributions of Primeval Galaxies
Ecole´ Doctorale d'Astronomie et Astrophysique d'^Ile-de-France UNIVERSITE´ PARIS VI - PIERRE & MARIE CURIE DOCTORATE THESIS to obtain the title of Doctor of the University of Pierre & Marie Curie in Astrophysics Presented by Alba Vidal Garc´ıa Modeling and interpretation of the ultraviolet spectral energy distributions of primeval galaxies Thesis Advisor: St´ephane Charlot prepared at Institut d'Astrophysique de Paris, CNRS (UMR 7095), Universit´ePierre & Marie Curie (Paris VI) with financial support from the European Research Council grant `ERC NEOGAL' Composition of the jury Reviewers: Alessandro Bressan - SISSA, Trieste, Italy Rosa Gonzalez´ Delgado - IAA (CSIC), Granada, Spain Advisor: St´ephane Charlot - IAP, Paris, France President: Patrick Boisse´ - IAP, Paris, France Examinators: Jeremy Blaizot - CRAL, Observatoire de Lyon, France Vianney Lebouteiller - CEA, Saclay, France Dedicatoria v Contents Abstract vii R´esum´e ix 1 Introduction 3 1.1 Historical context . .4 1.2 Early epochs of the Universe . .5 1.3 Galaxytypes ......................................6 1.4 Components of a Galaxy . .8 1.4.1 Classification of stars . .9 1.4.2 The ISM: components and phases . .9 1.4.3 Physical processes in the ISM . 12 1.5 Chemical content of a galaxy . 17 1.6 Galaxy spectral energy distributions . 17 1.7 Future observing facilities . 19 1.8 Outline ......................................... 20 2 Modeling spectral energy distributions of galaxies 23 2.1 Stellar emission . 24 2.1.1 Stellar population synthesis codes . 24 2.1.2 Evolutionary tracks . 25 2.1.3 IMF . 29 2.1.4 Stellar spectral libraries . 30 2.2 Absorption and emission in the ISM . 31 2.2.1 Photoionization code: CLOUDY ....................... -
Arxiv:1704.01678V2 [Astro-Ph.GA] 28 Jul 2017 Been Notoriously Difficult, Resulting Mostly in Upper Lim- Highest Escape Fractions Measured to Date Among Low- Its (E.G
Submitted: 3 March 2017 Preprint typeset using LATEX style AASTeX6 v. 1.0 MRK 71 / NGC 2366: THE NEAREST GREEN PEA ANALOG Genoveva Micheva1, M. S. Oey1, Anne E. Jaskot2, and Bethan L. James3 (Accepted 24 July 2017) 1University of Michigan, 311 West Hall, 1085 S. University Ave, Ann Arbor, MI 48109-1107, USA 2Department of Astronomy, Smith College, Northampton, MA 01063, USA 3STScI, 3700 San Martin Drive, Baltimore, MD 21218, USA ABSTRACT We present the remarkable discovery that the dwarf irregular galaxy NGC 2366 is an excellent analog of the Green Pea (GP) galaxies, which are characterized by extremely high ionization parameters. The similarities are driven predominantly by the giant H II region Markarian 71 (Mrk 71). We compare the system with GPs in terms of morphology, excitation properties, specific star-formation rate, kinematics, absorption of low-ionization species, reddening, and chemical abundance, and find consistencies throughout. Since extreme GPs are associated with both candidate and confirmed Lyman continuum (LyC) emitters, Mrk 71/NGC 2366 is thus also a good candidate for LyC escape. The spatially resolved data for this object show a superbubble blowout generated by mechanical feedback from one of its two super star clusters (SSCs), Knot B, while the extreme ionization properties are driven by the . 1 Myr-old, enshrouded SSC Knot A, which has ∼ 10 times higher ionizing luminosity. Very massive stars (> 100 M ) may be present in this remarkable object. Ionization-parameter mapping indicates the blowout region is optically thin in the LyC, and the general properties also suggest LyC escape in the line of sight. -
March 21–25, 2016
FORTY-SEVENTH LUNAR AND PLANETARY SCIENCE CONFERENCE PROGRAM OF TECHNICAL SESSIONS MARCH 21–25, 2016 The Woodlands Waterway Marriott Hotel and Convention Center The Woodlands, Texas INSTITUTIONAL SUPPORT Universities Space Research Association Lunar and Planetary Institute National Aeronautics and Space Administration CONFERENCE CO-CHAIRS Stephen Mackwell, Lunar and Planetary Institute Eileen Stansbery, NASA Johnson Space Center PROGRAM COMMITTEE CHAIRS David Draper, NASA Johnson Space Center Walter Kiefer, Lunar and Planetary Institute PROGRAM COMMITTEE P. Doug Archer, NASA Johnson Space Center Nicolas LeCorvec, Lunar and Planetary Institute Katherine Bermingham, University of Maryland Yo Matsubara, Smithsonian Institute Janice Bishop, SETI and NASA Ames Research Center Francis McCubbin, NASA Johnson Space Center Jeremy Boyce, University of California, Los Angeles Andrew Needham, Carnegie Institution of Washington Lisa Danielson, NASA Johnson Space Center Lan-Anh Nguyen, NASA Johnson Space Center Deepak Dhingra, University of Idaho Paul Niles, NASA Johnson Space Center Stephen Elardo, Carnegie Institution of Washington Dorothy Oehler, NASA Johnson Space Center Marc Fries, NASA Johnson Space Center D. Alex Patthoff, Jet Propulsion Laboratory Cyrena Goodrich, Lunar and Planetary Institute Elizabeth Rampe, Aerodyne Industries, Jacobs JETS at John Gruener, NASA Johnson Space Center NASA Johnson Space Center Justin Hagerty, U.S. Geological Survey Carol Raymond, Jet Propulsion Laboratory Lindsay Hays, Jet Propulsion Laboratory Paul Schenk, -
Digitalcommons@UTEP
University of Texas at El Paso DigitalCommons@UTEP Open Access Theses & Dissertations 2017-01-01 Her Alessandra Narvaez-Varela University of Texas at El Paso, [email protected] Follow this and additional works at: https://digitalcommons.utep.edu/open_etd Part of the Creative Writing Commons, and the Women's Studies Commons Recommended Citation Narvaez-Varela, Alessandra, "Her" (2017). Open Access Theses & Dissertations. 509. https://digitalcommons.utep.edu/open_etd/509 This is brought to you for free and open access by DigitalCommons@UTEP. It has been accepted for inclusion in Open Access Theses & Dissertations by an authorized administrator of DigitalCommons@UTEP. For more information, please contact [email protected]. HER ALESSANDRA NARVÁEZ-VARELA Master's Program in Creative Writing APPROVED: Sasha Pimentel, Chair Andrea Cote-Botero, Ph.D. David Ruiter, Ph.D. Charles Ambler, Ph.D. Dean of the Graduate School . Copyright © by Alessandra Narváez-Varela 2017 For my mother—Amanda Socorro Varela Aragón— the original Her HER by ALESSANDRA NARVÁEZ-VARELA, B.S in Biology, B.A. in Creative Writing THESIS Presented to the Faculty of the Graduate School of The University of Texas at El Paso in Partial Fulfillment of the Requirements for the Degree of MASTER OF FINE ARTS Department of Creative Writing THE UNIVERSITY OF TEXAS AT EL PASO December 2017 Acknowledgements Thank you to the editors of Duende for publishing a previous version of “The Cosmic Millimeter,” and to the Department of Hispanic Studies at the University of Houston for the forthcoming publication of a chapbook featuring the following poems: “Curves,” “Savage Nerd Cunt,” “Beauty,” “Bride,” “An Education,” “Daddy, Look at Me,” and “Cut.” Thank you to Casa Cultural de las Américas for sponsoring the reading that made this chapbook possible. -
Nova Report 2006-2007
NOVA REPORTNOVA 2006 - 2007 NOVA REPORT 2006-2007 Illustration on the front cover The cover image shows a composite image of the supernova remnant Cassiopeia A (Cas A). This object is the brightest radio source in the sky, and has been created by a supernova explosion about 330 year ago. The star itself had a mass of around 20 times the mass of the sun, but by the time it exploded it must have lost most of the outer layers. The red and green colors in the image are obtained from a million second observation of Cas A with the Chandra X-ray Observatory. The blue image is obtained with the Very Large Array at a wavelength of 21.7 cm. The emission is caused by very high energy electrons swirling around in a magnetic field. The red image is based on the ratio of line emission of Si XIII over Mg XI, which brings out the bi-polar, jet-like, structure. The green image is the Si XIII line emission itself, showing that most X-ray emission comes from a shell of stellar debris. Faintly visible in green in the center is a point-like source, which is presumably the neutron star, created just prior to the supernova explosion. Image credits: Creation/compilation: Jacco Vink. The data were obtained from: NASA Chandra X-ray observatory and Very Large Array (downloaded from Astronomy Digital Image Library http://adil.ncsa.uiuc. edu). Related scientific publications: Hwang, Vink, et al., 2004, Astrophys. J. 615, L117; Helder and Vink, 2008, Astrophys. J. in press. -
Monthly Newsletter of the Durban Centre - March 2018
Page 1 Monthly Newsletter of the Durban Centre - March 2018 Page 2 Table of Contents Chairman’s Chatter …...…………………….……….………..….…… 3 Andrew Gray …………………………………………...………………. 5 The Hyades Star Cluster …...………………………….…….……….. 6 At the Eye Piece …………………………………………….….…….... 9 The Cover Image - Antennae Nebula …….……………………….. 11 Galaxy - Part 2 ….………………………………..………………….... 13 Self-Taught Astronomer …………………………………..………… 21 The Month Ahead …..…………………...….…….……………..…… 24 Minutes of the Previous Meeting …………………………….……. 25 Public Viewing Roster …………………………….……….…..……. 26 Pre-loved Telescope Equipment …………………………...……… 28 ASSA Symposium 2018 ………………………...……….…......…… 29 Member Submissions Disclaimer: The views expressed in ‘nDaba are solely those of the writer and are not necessarily the views of the Durban Centre, nor the Editor. All images and content is the work of the respective copyright owner Page 3 Chairman’s Chatter By Mike Hadlow Dear Members, The third month of the year is upon us and already the viewing conditions have been more favourable over the last few nights. Let’s hope it continues and we have clear skies and good viewing for the next five or six months. Our February meeting was well attended, with our main speaker being Dr Matt Hilton from the Astrophysics and Cosmology Research Unit at UKZN who gave us an excellent presentation on gravity waves. We really have to be thankful to Dr Hilton from ACRU UKZN for giving us his time to give us presentations and hope that we can maintain our relationship with ACRU and that we can draw other speakers from his colleagues and other research students! Thanks must also go to Debbie Abel and Piet Strauss for their monthly presentations on NASA and the sky for the following month, respectively. -
Evidence of Environmental Dependencies of Type Ia Supernovae from the Nearby Supernova Factory Indicated by Local Hα?
A&A 560, A66 (2013) Astronomy DOI: 10.1051/0004-6361/201322104 & c ESO 2013 Astrophysics Evidence of environmental dependencies of Type Ia supernovae from the Nearby Supernova Factory indicated by local Hα? M. Rigault1, Y. Copin1, G. Aldering2, P. Antilogus3, C. Aragon2, S. Bailey2, C. Baltay4, S. Bongard3, C. Buton5, A. Canto3, F. Cellier-Holzem3, M. Childress6, N. Chotard1, H. K. Fakhouri2;7, U. Feindt,5, M. Fleury3, E. Gangler1, P. Greskovic5, J. Guy3, A. G. Kim2, M. Kowalski5, S. Lombardo5, J. Nordin2;8, P. Nugent9;10, R. Pain3, E. Pécontal11, R. Pereira1, S. Perlmutter2;7, D. Rabinowitz4, K. Runge2, C. Saunders2, R. Scalzo6, G. Smadja1, C. Tao12;13, R. C. Thomas9, and B. A. Weaver14 (The Nearby Supernova Factory) 1 Université de Lyon, Université de Lyon 1; CNRS/IN2P3, Institut de Physique Nucléaire de Lyon, 69622 Villeurbanne Cedex, France e-mail: [email protected] 2 Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA 3 Laboratoire de Physique Nucléaire et des Hautes Énergies, Université Pierre et Marie Curie Paris 6, Université Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, 75252 Paris Cedex 05, France 4 Department of Physics, Yale University, New Haven, CT 06520-8121, USA 5 Physikalisches Institut, Universität Bonn, Nußallee 12, 53115 Bonn, Germany 6 Research School of Astronomy and Astrophysics, The Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Creek ACT 2611, Australia 7 Department of Physics, University of California Berkeley, 366 LeConte