The Global Content, Distribution, and Kinematics of Interstellar O VI in the Large Magellanic Cloud
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A Fuse Survey of the Rotation Rates of Very Massive Stars in the Small and Large Magellanic Clouds
The Astrophysical Journal, 700:844–858, 2009 July 20 doi:10.1088/0004-637X/700/1/844 C 2009. The American Astronomical Society. All rights reserved. Printed in the U.S.A. A FUSE SURVEY OF THE ROTATION RATES OF VERY MASSIVE STARS IN THE SMALL AND LARGE MAGELLANIC CLOUDS Laura R. Penny1 and Douglas R. Gies2 1 Department of Physics and Astronomy, The College of Charleston, Charleston, SC 29424, USA; [email protected] 2 Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 4106, Atlanta, GA 30302-4106, USA; [email protected] Received 2009 February 3; accepted 2009 May 26; published 2009 July 6 ABSTRACT We present projected rotational velocity values for 97 Galactic, 55 SMC, and 106 LMC O-B type stars from archival FUSE observations. The evolved and unevolved samples from each environment are compared through the Kolmogorov–Smirnov test to determine if the distribution of equatorial rotational velocities is metallicity dependent for these massive objects. Stellar interior models predict that massive stars with SMC metallicity will have significantly reduced angular momentum loss on the main sequence compared to their Galactic counterparts. Our results find some support for this prediction but also show that even at Galactic metallicity, evolved and unevolved massive stars have fairly similar fractions of stars with large V sin i values. Macroturbulent broadening that is present in the spectral features of Galactic evolved massive stars is lower in the LMC and SMC samples. This suggests the processes that lead to macroturbulence are dependent upon metallicity. -
A FUSE Survey of Interstellar Molecular Hydrogen in the Small
DRAFT VERSION OCTOBER 25, 2018 Preprint typeset using LATEX style emulateapj v. 04/03/99 A FUSE SURVEY OF INTERSTELLAR MOLECULAR HYDROGEN IN THE SMALL AND LARGE MAGELLANIC CLOUDS1 JASON TUMLINSON 2, J. MICHAEL SHULL2,3, BRIAN L. RACHFORD2, MATTHEW K. BROWNING2, THEODORE P. SNOW2, ALEX W. FULLERTON4,5, EDWARD B. JENKINS6, BLAIR D. SAVAGE7, PAUL A. CROWTHER8, H. WARREN MOOS5, KENNETH R. SEMBACH5, GEORGE SONNEBORN9, & DONALD G. YORK10 Draft version October 25, 2018 ABSTRACT We describe a moderate-resolution FUSE survey of H2 along 70 sight lines to the Small and Large Magellanic Clouds, using hot stars as background sources. FUSE spectra of 67% of observed Magellanic Cloud sources (52% of LMC and 92% of SMC) exhibit absorption lines from the H2 Lyman and Werner bands between 912 and 14 −2 1120 Å. Our survey is sensitive to N(H2) ≥ 10 cm ; the highest column densities are log N(H2) = 19.9 in the LMC and 20.6 in the SMC. We find reduced H2 abundances in the Magellanic Clouds relative to the Milky Way, +0.005 +0.006 with average molecular fractions h fH2i =0.010−0.002 for the SMC and h fH2i =0.012−0.003 for the LMC, compared with h fH2i =0.095 for the Galactic disk over a similar range of reddening. The dominant uncertainty in this measurement results from the systematic differences between 21 cm radio emission and Lyα in pencil-beam sight 6 lines as measures of N(H I). These results imply that the diffuse H2 masses of the LMC and SMC are 8 × 10 M⊙ 6 and 2 × 10 M⊙, respectively, 2% and 0.5% of the H I masses derived from 21 cm emission measurements. -
The R136 Star Cluster Dissected with Hubble Space Telescope/STIS
MNRAS 000, 1–39 (2015) Preprint 29 January 2016 Compiled using MNRAS LATEXstylefilev3.0 The R136 star cluster dissected with Hubble Space Telescope/STIS. I. Far-ultraviolet spectroscopic census and the origin of He ii λ1640 in young star clusters Paul A. Crowther1⋆, S.M. Caballero-Nieves1, K.A. Bostroem2,3,J.Ma´ız Apell´aniz4, F.R.N. Schneider5,6,N.R.Walborn2,C.R.Angus1,7,I.Brott8,A.Bonanos9, A. de Koter10,11,S.E.deMink10,C.J.Evans12,G.Gr¨afener13,A.Herrero14,15, I.D. Howarth16, N. Langer6,D.J.Lennon17,J.Puls18,H.Sana2,11,J.S.Vink13 1Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK 2Space Telescope Science Institute, 3700 San Martin Drive, Baltimore MD 21218, USA 3Department of Physics, University of California, Davis, 1 Shields Ave, Davis CA 95616, USA 4Centro de Astrobiologi´a, CSIC/INTA, Campus ESAC, Apartado Postal 78, E-28 691 Villanueva de la Ca˜nada, Madrid, Spain 5 Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, UK 6 Argelanger-Institut fur¨ Astronomie der Universit¨at Bonn, Auf dem Hugel¨ 71, D-53121 Bonn, Germany 7 Department of Physics, University of Warwick, Gibbet Hill Rd, Coventry CV4 7AL, UK 8 Institute for Astrophysics, Tuerkenschanzstr. 17, AT-1180 Vienna, Austria 9 Institute of Astronomy & Astrophysics, National Observatory of Athens, I. Metaxa & Vas. Pavlou St, P. Penteli 15236, Greece 10 Astronomical Institute Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ, Amsterdam, Netherlands 11 Institute of Astronomy, KU Leuven, Celestijnenlaan -
Supernova O Buco Nero?
UNIVERSITÀ DEGLI STUDI DI PADOVA DIPARTIMENTO DI FISICA E ASTRONOMIA G. GALILEI Corso di laurea in Astronomia Tesi di Laurea Triennale DESTINO FINALE DELLE STELLE MOLTO MASSICCE: SUPERNOVA O BUCO NERO? Relatore: Prof.ssa Paola Marigo Correlatore: Alessandra Slemer Laureanda: Francesca Gerardi Matricola: 1072531 Anno Accademico 2015/2016 2 Indice Abstract 5 1 Cenni di evoluzione stellare 7 1.1 Classicazione stellare . 7 1.2 Stelle molto massicce (VMOs) . 11 1.2.1 Proprietà evolutive . 11 1.2.2 VMOs osservati . 15 2 PCSNe: pair creation supernovae 17 2.0.1 Considerazioni energetiche . 19 2.1 Arricchimento del mezzo interstellare . 20 2.2 Osservabilità a bassi redshift . 24 2.2.1 Curve di luce . 24 3 Conclusioni 29 3 4 Abstract Denendo la stella come un oggetto che irradia energia da una sorgente interna e che co- stituisce un sistema legato dalla sua stessa gravità , di norma si considerano stelle quelle la cui massa è inclusa tra le 0:08M , limite inferiore dettato dalla minima temperatura necessaria a innescare il bruciamento dell'idrogeno, e le 100M , limite superiore per la stabilità dinamica. La recente osservazione di stelle di massa superiore ha stimolato la ricerca verso le cosid- dette stelle molto massicce, ovvero stelle con massa iniziale maggiore di 100M ; sulla base della più recente letteratura se ne discutono le principali proprietà evolutive, il contribu- to all'arricchimento chimico del mezzo interstellare e il destino nale. L'esito nale sarà l'esplosione di supernova di tipo pair creation (PCSN) o il collasso diretto in buco nero, secondo un criterio dettato dalla massa del nucleo di elio MHe. -
Effects of Rotation Arund the Axis on the Stars, Galaxy and Rotation of Universe* Weitter Duckss1
Effects of Rotation Arund the Axis on the Stars, Galaxy and Rotation of Universe* Weitter Duckss1 1Independent Researcher, Zadar, Croatia *Project: https://www.svemir-ipaksevrti.com/Universe-and-rotation.html; (https://www.svemir-ipaksevrti.com/) Abstract: The article analyzes the blueshift of the objects, through realized measurements of galaxies, mergers and collisions of galaxies and clusters of galaxies and measurements of different galactic speeds, where the closer galaxies move faster than the significantly more distant ones. The clusters of galaxies are analyzed through their non-zero value rotations and gravitational connection of objects inside a cluster, supercluster or a group of galaxies. The constant growth of objects and systems is visible through the constant influx of space material to Earth and other objects inside our system, through percussive craters, scattered around the system, collisions and mergers of objects, galaxies and clusters of galaxies. Atom and its formation, joining into pairs, growth and disintegration are analyzed through atoms of the same values of structure, different aggregate states and contiguous atoms of different aggregate states. The disintegration of complex atoms is followed with the temperature increase above the boiling point of atoms and compounds. The effects of rotation around an axis are analyzed from the small objects through stars, galaxies, superclusters and to the rotation of Universe. The objects' speeds of rotation and their effects are analyzed through the formation and appearance of a system (the formation of orbits, the asteroid belt, gas disk, the appearance of galaxies), its influence on temperature, surface gravity, the force of a magnetic field, the size of a radius. -
Highly Ionized Plasma in the Large Magellanic Cloud: Evidence for ⋆ Outflows and a Possible Galactic Wind
Mon. Not. R. Astron. Soc. 377, 687–704 (2007) doi:10.1111/j.1365-2966.2007.11631.x Highly ionized plasma in the Large Magellanic Cloud: evidence for ⋆ outflows and a possible galactic wind N. Lehner† and J. C. Howk Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556, USA Accepted 2007 February 15. Received 2007 February 15; in original form 2006 November 30 ABSTRACT Based on an analysis of the interstellar highly ionized species C IV,SiIV,NV and O VI observed in the Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) E140M spectra of four hot stars in the Large Magellanic Cloud (LMC), we find evidence for a hot LMC halo fed by energetic outflows from the LMC disc and even possibly an LMC galactic wind. Signatures for such outflows 1 are the intermediate- and high-velocity components (vLSR 100 km s− ) relative to the LMC disc observed in the high- and low-ion absorption profiles. The stellar environments produce strong, narrow (T 2 104 K) components of C IV and Si IV associated with the LMC disc; × in particular they are likely signatures of H II regions and expanding shells. Broad components are observed in the profiles of C IV,SiIV and O VI with their widths implying hot, collisionally ionized gas at temperatures of a few times 105 K. There is a striking similarity in the O VI/C IV ratios for the broad LMC and high-velocity components, suggesting much of the material at 1 vLSR 100 km s− is associated with the LMC. -
White Dwarfs
White Dwarfs • Low mass stars are unable to reach high enough temperatures to ignite elements heavier than LECTURE 15: hydrogen in their core and become white dwarfs. Planetary nebulae reveal them. Can be He or CO. WHITE DWARFS Rarely NeOMg. AND THE ADVANCED EVOLUTION • Hot exposed core of an evolved low mass star. OF MASSIVE STARS • Supported by electron degeneracy pressure. M 8M ≥ • Unable to produce energy by contracting or igniting http://apod.nasa.gov/apod/astropix.html nuclear reactions • As white dwarfs radiate energy, they become cooler and less luminous gradually fading into oblivion, but it can take a long time…. http://en.wikipedia.org/wiki/Ring_Nebula A white dwarf is the remnant of stellar evolution for stars between 0.08 and 8 solar masses (below 0.08 one can have brown dwarfs). They can be made The Ring Negula in Lyra (M57) out of helium, or more commonly carbon and oxygen 700 pc; magnitute 8.8 (rarely NeOMg). MASS RADIUS RELATION FOR WHITE DWARFS if supported by GM ρ 13 5/3 Pc = = 1.00× 10 (ρYe ) non-relativistic electron 2R degeneracy pressure ⎛ 3M ⎞ GM ⎜ 3 ⎟ 5/3 5/3 GM ρ ⎝ 4π R ⎠ 13 ⎛ 3M ⎞ ⎛ 1⎞ ≈ = 1.00× 10 ⎜ 3 ⎟ ⎜ ⎟ 2R 2R ⎝ 4π R ⎠ ⎝ 2⎠ 2 5/3 5/3 ⎛ 3G ⎞ M 13 ⎛ 3 ⎞ M ⎜ ⎟ = 1.00×10 ⎜ ⎟ 5 ⎝ 8π ⎠ R4 ⎝ 8π ⎠ R 2/3 1/3 13 ⎛ 3 ⎞ 1 M = 1.00×10 ⎜ ⎟ ⎝ 8π ⎠ GR 19 1/3 R = 3.63×10 / M More massive 1/3 white dwarfs 8 ⎛ M ⎞ Earth R = 6370 km R = 2.9×10 cm are smaller ⎝⎜ ⎠⎟ M Mass versus radius relation More massive white dwarf stars are denser for the radius How far can this go? Mass distribution! Most WDs cluster around 0.6 M!. -
Are Ultraluminous X-Ray Sources Intermediate Mass
EXAMINING VERY-LONG-TERM VARIABILITY IN X-RAY BINARIES: ARE ULTRALUMINOUS X-RAY SOURCES INTERMEDIATE MASS BLACK HOLES? By Deatrick Foster Dissertation Submitted to the Faculty of the Graduate School of Vanderbilt University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in PHYSICS December, 2013 Nashville, Tennessee Approved: Dr. Keivan G. Stassun Dr. Philip A. Charles Dr. David A. Weintraub Dr. Richard Haglund Dr. David J. Ernst DEDICATION This thesis is dedicated to the loving memory of Joe and Dollie. ACKNOWLEDGMENTS I would like to thank my advisers, Dr. Keivan Stassun and Dr. Philip Charles. Without their care, enthusiasm, encouragement and guidance this thesis would not have been possible. I am thankful for my PhD committee members, along with all of my collaborators. Your support was critical to my development as a scientist. I thank Dr. Hakeem Oluseyi, Dr. Abebe Kebede, Dr. James L. “Jim” Smith, Dr. Reva Kay Williams, and Dr. Anthony Johnson, Dr. Jarita Holbrook, and Dr. Doug Swartz for their sound advice, support, mentoring, and friendship. I would like to acknowledge the National Society of Black Physicists (NSBP), which was critical to my completing this PhD. I would also like to acknowledge funding I received in the form of a NASA Harriett G. Jenkins Fellowship (NASA- JPFP), a National Physical Science Consortium (NPSC) Fellowship, a Vanderbilt Initiative in Data-intensive Astrophysics (VIDA) Fellowship, and the Graduate As- sistance in Areas of National Need (GAANN) Fellowship. I would like to thank the Fisk-Vanderbilt Bridge Program for very critical support I received while at Vander- bilt, the Vanderbilt-Cape Town Partnership, the University of Cape Town and the South African Astronomical Observatory. -
Title Wide Field CO Mapping in the Region of IRAS 19312+1950
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by HKU Scholars Hub Title Wide Field CO Mapping in the Region of IRAS 19312+1950 Nakshima, J; Ladeyschikov, D; Sobolev, A; Zhang, Y; Hsia, C; Author(s) Yung, BHK Citation The Astrophysical Journal, 2016, v. 825, p. article no. 16 Issued Date 2016 URL http://hdl.handle.net/10722/229402 This work is licensed under a Creative Commons Attribution- Rights NonCommercial-NoDerivatives 4.0 International License. Accepted for publication in ApJ Wide Field CO Mapping in the Region of IRAS 19312+1950 Jun-ichi Nakashima1, Dmitry A. Ladeyschikov2, Andrej M. Sobolev2, Yong Zhang3,4, Chih-Hao Hsia3,4,5, Bosco H. K. Yung6 ABSTRACT We report the results of a wide field CO mapping in the region of IRAS 19312+1950. This IRAS object exhibits SiO/H2O/OH maser emission, and is embedded in a chemically-rich molecular component, of which the origin is still unknown. In order to reveal the entire structure and gas mass of the surrounding molecular component for the first time, we have mapped a wide region around IRAS 19312+1950 in the 12CO J = 1–0, 13CO J = 1–0 and C18O J = 1–0 lines using the Nobeyama 45m telescope. In conjunction with the archival CO maps, we investigated a region with a size up to 20′ 20′ around this IRAS object. We × calculated CO gas mass assuming the LTE condition, a stellar velocity against to the interstellar medium assuming an analytic model of a bow shock, and absolute luminosity using the latest archival data and trigonometric parallax distance. -
LECTURE 15 – Jerome Fang
LECTURE 15 – Jerome Fang - •Making heavy elements in low-mass stars: the s-process (review) •White dwarfs: diamonds in the sky •Evolution of high-mass stars (M > 8 M); post-helium burning fusion processes Review of evolution of low-mass stars (M < 8 M) AGB star HB star Making heavy elements: the s-process During the AGB phase (double shell burning), additional elements are produced via the s-process in the outer shells of the star Heavier elements are produced via neutron capture onto nuclei (add neutrons to nuclei one-by-one) The neutrons are byproducts of helium and carbon burning (see next slide) S-process can make elements from cobalt up to bismuth The “s” stands for “slow” because products decay easily, making it difficult to form stable nuclei Additional Nucleosynthesis – The s-process. Iron nuclei are the “seeds” of the s- process years 44.5 days This is called the slow process of neutron addition or the s-process. (There is also a r-process) Magenta = elements produced by fusion Brown = elements produced by the s-process Beginning of the s-process 63Cu 64Cu 12.7 h Z = Number of protons N = Number of neutrons 60Ni 61Ni 62Ni 63Ni 100 y Z 59Co 60Co 61Co 5.27 y 56Fe 57Fe 58Fe 59Fe 60Fe 44.5 d = (capture n, release ) N = (release e-,) Each row = different isotopes of an element The s-process of neutron addition Each neutron capture takes you one step to the right in this diagram. Each decay of a neutron to a proton inside the nucleus moves you up a left diagonal. -
The Processes Which Cause the Appearance of Objects and Systems
American Journal of Astronomy and Astrophysics 2018; 6(3): 72-80 http://www.sciencepublishinggroup.com/j/ajaa doi: 10.11648/j.ajaa.20180603.13 ISSN: 2376-4678 (Print); ISSN: 2376-4686 (Online) The Processes Which Cause the Appearance of Objects and Systems Weitter Duckss Independent Researcher, Zadar, Croatia Email address: To cite this article: Weitter Duckss. The Processes Which Cause the Appearance of Objects and Systems. American Journal of Astronomy and Astrophysics. Vol. 6, No. 3, 2018, pp. 72-80. doi: 10.11648/j.ajaa.20180603.13 Received : August 27, 2018; Accepted : September 30, 2018; Published : November 7, 2018 Abstract: The beginning of the formation of galaxies can be recognized in the planetary and stellar systems. The rotation speed of a galactic center determins the form of a galaxy an the ongoing processes. The forces of attraction and the rotation of stars firstly form binary systems. The objects that are locked down by their tidal forces or that posses an extremely slow rotation, i.e. they have no independent rotation – they don't have other objects orbiting around themselves; for example: Mercury, Venus and the majority of satellites. A very fast cyclone rotation (in an elliptical galaxy) creates huge friction, whichheats up matter; that can be seen on quasars and very fast-rotating small objects (stars) through the emission of radiation that takes place on the poles. A vast number of stars and other matter (the center of a galaxy), when rotating around the common center, act as a single body, related to the rest of the galaxy. A slow rotation of a galactic center (as in the stellar clusters) does not create a recognizable center (the center looks more like the ones of close binary systems), while the fast rotation creates the center that ranges from the northern to the southern pole of the center. -
A NEW SPECTRAL CLASSIFICATION SYSTEM for the EARLIEST O STARS: DEFINITION of TYPE O2 Nolan R
The Astronomical Journal, 123:2754–2771, 2002 May # 2002. The American Astronomical Society. All rights reserved. Printed in U.S.A. A NEW SPECTRAL CLASSIFICATION SYSTEM FOR THE EARLIEST O STARS: DEFINITION OF TYPE O2 Nolan R. Walborn1,2 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218; [email protected] Ian D. Howarth3 Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK; [email protected] Daniel J. Lennon4 Isaac Newton Group, Apartado 321, E-38700 Santa Cruz de La Palma, Canary Islands, Spain; [email protected] Philip Massey1,2 and M. S. Oey1 Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001; [email protected], [email protected] Anthony F. J. Moffat1 and Gwen Skalkowski De´partement de Physique, Universite´ de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, QC H3C 3J7, Canada; moff[email protected], [email protected] Nidia I. Morrell1,5 Facultad de Ciencias Astrono´micas y Geofı´sicas, Universidad Nacional de La Plata, Paseo del Bosque, 1900 La Plata, Argentina; [email protected] Laurent Drissen2 De´partement de Physique, Universite´ Laval, Ste-Foy, QC G1K 7P4, Canada; [email protected] and Joel Wm. Parker1 Southwest Research Institute, 1050 Walnut Street, Suite 426, Boulder, CO 80302; [email protected] Received 2001 September 18; accepted 2002 January 22 ABSTRACT High-quality, blue-violet spectroscopic data are collected for 24 stars that have been classified as type O3 and that display the hallmark N iv and N v lines. A new member of the class is presented; it is the second known in the Cyg OB2 association, and only the second in the northern hemisphere.