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Discovery of X-Ray Emission from the Wolf-Rayet Star WR142 of Oxygen Subtype
Discovery of X-ray Emission from the Wolf-Rayet star WR 142 of oxygen subtype L. M. Oskinova, W.-R. Hamann, A. Feldmeier Institute for Physics and Astronomy, University Potsdam, 14476 Potsdam, Germany [email protected] R. Ignace Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37614, USA Y.-H. Chu Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801, USA ABSTRACT We report the discovery of weak yet hard X-ray emission from the Wolf-Rayet (WR) star WR 142 with the XMM-Newton X-ray telescope. Being of spectral subtype WO2, WR142 is a massive star in a very advanced evolutionary stage, short before its explosion as a supernova or γ-ray burst. This is the first detection of X-ray emission from a WO-type star. We rule out any serendipitous X-ray sources within ≈ 1′′ of WR142. WR142 has an X-ray luminosity of 30 −1 < −8 LX = 7 × 10 ergs , which constitutes only ∼10 of its bolometric luminosity. The hard X- ray spectrum suggests a plasma temperature of about 100MK. Commonly, X-ray emission from stellar winds is attributed to embedded shocks due to the intrinsic instability of the radiation driving. From qualitative considerations we conclude that this mechanism cannot account for the hardness of the observed radiation. There are no hints for a binary companion. Therefore the only remaining, albeit speculative explanation must refer to magnetic activity. Possibly related, WR 142 seems to rotate extremely fast, as indicated by the unusually round profiles of its optical emission lines. -
198 6Apj. . .300. .37 9T the Astrophysical Journal, 300
9T .37 The Astrophysical Journal, 300:379-395,1986 January 1 © 1986. The American Astronomical Society. All rights reserved. Printed in U.S.A. .300. 6ApJ. 198 SPECTROSCOPIC STUDIES OF WOLF-RAYET STARS. III. THE WC SUBCLASS Ana V. Torres and Peter S. Conti1,2 Joint Institute for Laboratory Astrophysics, University of Colorado and National Bureau of Standards AND Philip Massey2 Kitt Peak National Observatory, National Optical Astronomy Observatories Received 1985 AprilS; accepted 1985 June 28 ABSTRACT We present spectrophotometric data for the major optical emission lines of 64 Galactic and 18 Large Magellanic Cloud (LMC) WC stars. Using line ratios of O v A5590, C m 25696, and C iv 25806 we quantify the subtype classification. A few Galactic stars are reclassified, and nearly all the LMC WC stars are found to be of type WC4. Thus there is even a greater discrepancy in the distribution of WC subtypes between the LMC and the Galaxy than previously assumed, since WC4 types in the Galaxy are rare. New measures of the line widths of C in 24650 are found to correlate nicely with the (revised) WC subtypes, although a few stars have lines too wide for their line ratios. Two of the most discrepant stars, WR 125 and WR 140, also show nonthermal radio emission and are strong X-ray sources. Terminal wind velocities are estimated from an excitation—line width relation. The terminal velocities range from 1000 km s_1 for the latest subtypes to 5000 km s "1 for the earliest types. Subject headings: galaxies: Magellanic Clouds — stars: stellar statistics— stars: winds — stars: Wolf-Rayet I. -
CURRICULUM VITAE: Dr Richard Ignace
CURRICULUM VITAE: Dr Richard Ignace Address: Department of Physics & Astronomy Office of Undergraduate Research College of Arts & Sciences Honors College EAST TENNESSEE STATE UNIVERSITY EAST TENNESSEE STATE UNIVERSITY Johnson City, TN 37614 Johnson City, TN 37614 Email: [email protected] [email protected] Web: faculty.etsu.edu/ignace www.etsu.edu/honors/ug research Phone/Fax: (423) 439-6904 / (423) 439-6905 (423) 439-6073 / (423) 439-6080 EDUCATION Ph.D. in Astronomy, University of Wisconsin 1996 M.S. in Physics, University of Wisconsin 1994 M.S. in Astronomy, University of Wisconsin 1993 B.S. in Astronomy, Indiana University 1991 POSITIONS HELD Aug 2016–present, Consultant, Tri-Alpha Energy Jan 2015–present, Director of Undergraduate Research Activities, East Tennessee State University Aug 2013–present, Full Professor: East Tennessee State University Aug 2007–Jul 2013, Associate Professor: East Tennessee State University Aug 2003–Jul 2007, Assistant Professor: East Tennessee State University Sep 2002–Jul 2003, Assistant Scientist: University of Wisconsin Aug 1999–Aug 2002, Visiting Assistant Professor: University of Iowa Nov 1996–Aug 1999, Postdoctoral Research Assistant: University of Glasgow SELECTED PROFESSIONAL ACTIVITIES Involved with service to discipline, institution, and community As Director of Undergraduate Research & Creative Activities, I administrate grant programs and activ- ities that support undergraduate scholarship, plus advocate for undergraduate research. Successful with publishing scholarly articles and competing for grant funding; author of the astron- omy textbook “Astro4U: An Introduction to the Science of the Cosmos,” of the popular astronomy book “Understanding the Universe,” and co-editor of the conference proceedings “The Nature and Evolution of Disks around Hot Stars” Principal organizer for STELLAR POLARIMETRY: FROM BIRTH TO DEATH, Jun 2011; and THE NATURE AND EVOLUTION OF DISKS AROUND HOT STARS, Jul 2004. -
Discovery of X-Ray Emission from the Wolf–Rayet Star Wr 142 of Oxygen Subtype
The Astrophysical Journal, 693:L44–L48, 2009 March 1 doi:10.1088/0004-637X/693/1/L44 c 2009. The American Astronomical Society. All rights reserved. Printed in the U.S.A. DISCOVERY OF X-RAY EMISSION FROM THE WOLF–RAYET STAR WR 142 OF OXYGEN SUBTYPE L. M. Oskinova1, W.-R. Hamann1, A. Feldmeier1, R. Ignace2, and Y.-H. Chu3 1 Institute for Physics and Astronomy, University Potsdam, 14476 Potsdam, Germany; [email protected] 2 Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37614, USA 3 Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801, USA Received 2008 December 8; accepted 2009 January 7; published 2009 February 16 ABSTRACT We report the discovery of weak yet hard X-ray emission from the Wolf–Rayet (WR) star WR 142 with the XMM-Newton X-ray telescope. Being of spectral subtype WO2, WR 142 is a massive star in a very advanced evolutionary stage shortly before its explosion as a supernova or γ -ray burst. This is the first detection of X-ray emission from a WO-type star. We rule out any serendipitous X-ray sources within ≈ 1 of WR 142. WR 142 has 30 −1 −8 an X-ray luminosity of LX ≈ 7 × 10 erg s , which constitutes only 10 of its bolometric luminosity. The hard X-ray spectrum suggests a plasma temperature of about 100 MK. Commonly, X-ray emission from stellar winds is attributed to embedded shocks due to the intrinsic instability of the radiation driving. -
FAR ULTRAVIOLET SPECTROSCOPIC EXPLORER SPECTROSCOPY of the O Vi RESONANCE DOUBLET in SAND 2 (WO) Paul A
The Astrophysical Journal, 538:L51±L55, 2000 July 20 q 2000. The American Astronomical Society. All rights reserved. Printed in U.S.A. FAR ULTRAVIOLET SPECTROSCOPIC EXPLORER SPECTROSCOPY OF THE O vi RESONANCE DOUBLET IN SAND 2 (WO) Paul A. Crowther,1 A. W. Fullerton,2,3 D. J. Hillier,4 K. Brownsberger,5 L. Dessart,1,6 A. J. Willis,1 O. De Marco,1 M. J. Barlow,1 J. B. Hutchings,7 D. L. Massa,8 D. C. Morton,7 and G. Sonneborn9 Received 2000 March 17; accepted 2000 June 8; published 2000 July 14 ABSTRACT We present Far Ultraviolet Spectroscopic Explorer spectroscopy of Sand 2, an LMC WO-type Wolf-Rayet star, revealing the O vi resonance P Cygni doublet at 1032±1038 AÊ . These data are combined with Hubble Space Telescope Faint Object Spectrograph ultraviolet and Mount Stromlo 2.3 m optical spectroscopy and analyzed using a spherical, non-LTE, line-blanketed code. Our study reveals exceptional stellar parameters: T¤ » 21 Ç 25 21 150,000 K,v` = 4100 km s , log (L/L,,) = 5.3 , andM=1 # 10 M yr , if we adopt a volume ®lling factor » 5 » 10.10 of 10%. Elemental abundances ofC/He 0.7 0.2 and O/He 0.1520.05 by number qualitatively support pre- vious recombination line studies. We con®rm that Sand 2 is more chemically enriched in carbon than LMC WC stars and that it is expected to undergo a supernova explosion within the next5 # 10 4 yr. Subject headings: stars: evolution Ð stars: individual (Sand 2) Ð stars: Wolf-Rayet 1. -
New Observational Results on the Colliding Wind WR+O Binary WR 30A
Wolf-Rayet Phenomena in Massive Stars and Starburst Galaxies Proceedings IAU Symposium No. 193, @1999 IAU K.A. van der Hucht, G. Koenigsberger & P.R.J. Eenens, eds. New observational results on the colliding wind WR+O binary WR 30a Eric Gosset", Pierre Royer I, Gregor Rauw", Jean Manfroid", and Jean-Marie Vreux Institut d'Astrophysique et de Geophsisique, Unioersite de Liege, avenue de Cointe, 5, B-4000 Liege, Belgium 1. Introduction WR 30a (MS 4) was first suspected as a possible Wolf-Rayet star by McConnell & Sanduleak (1970) during a deep objective-prism survey performed around the Carina Nebula region. From subsequent studies, the spectrum turned out to be composite, with a WR component classified W04 (or alternatively WC4, W05 and WC3) and an 0 component classified 04. Niemela (1995) reported the first, and up-to-now unique, radial velocity study for that star. She noticed large variations of C IV A4658 from night to night, suggesting that WR 30a might be a short period binary. A plot of the C IV emission-line velocities versus the He II absorption ones clearly indicates that they are exhibiting opposite binary motions. The apparent velocity amplitudes imply a rather low mass ratio Mwo 4/Mo4 == 0.15, although the radial velocities of the C IV line could be distorted due to line-profile variations. In the present paper, we confirm the binary nature of WR 30a and propose, for the first time, a value for the orbital period of the system: P == 4.62 days. Other orbital parameters are also derived and discussed. -
High Energy Processes in Young Stellar Objects and High-Mass X-Ray Binaries
High energy processes in young stellar objects and high-mass X-ray binaries Pere Munar i Adrover Aquesta tesi doctoral està subjecta a la llicència Reconeixement- NoComercial 3.0. Espanya de Creative Commons. Esta tesis doctoral está sujeta a la licencia Reconocimiento - NoComercial 3.0. España de Creative Commons. This doctoral thesis is licensed under the Creative Commons Attribution-NonCommercial 3.0. Spain License. UNIVERSITAT DE BARCELONA Departament d’Astronomia i Meteorologia High energy processes in young stellar objects and high-mass X-ray binaries Pere Munar i Adrover Barcelona (Spain), March 2014 Programa de Doctorat en F´ısica L´ınia de recerca en Astronomia i Astrof´ısica 2010-2014 Mem`oria presentada per Pere Munar i Adrover per optar al grau de Doctor en F´ısica Director i Tutor Prof. Josep Maria Paredes Poy Contents Resum de la tesi v 1 Introduction 1 1.1High-energyastrophysics............................. 1 1.2 High-energy emission processes ......................... 2 1.2.1 Bremsstrahlung.............................. 3 1.2.2 Relativistic Bremsstrahlung ....................... 5 1.2.3 Synchrotron................................ 6 1.2.4 InverseCompton............................. 8 1.2.5 pp collisions ................................ 8 1.2.6 Photoelectricabsorption......................... 10 1.2.7 Coulombian losses ............................ 10 1.3 Particle acceleration ............................... 11 I Young Stellar Objects 13 2 Introduction 15 2.1Star-formingregions............................... 15 2.2Highenergyemissionfromstar-formingregions................ 16 2.2.1 High-massprotostars........................... 16 2.2.2 Low-massprotostars........................... 17 2.2.3 Otherhigh-energyemittingsources................... 18 3 Exploring the association of Fermi sources with young galactic objects 21 3.1Introduction.................................... 21 3.2 Cross-correlation of the First Fermi Catalog with massive young galactic objects...................................... -
Magnetic Fields in Massive Stars, Their Winds, and Their Nebulae
Noname manuscript No. (will be inserted by the editor) Magnetic Fields in Massive Stars, their Winds, and their Nebulae Rolf Walder · Doris Folini · Georges Meynet Received: date / Accepted: date Abstract Massive stars are crucial building blocks of galaxies and the universe, as production sites of heavy elements and as stirring agents and energy providers through stellar winds and supernovae. The field of magnetic massive stars has seen tremendous progress in recent years. Different perspectives – ranging from direct field measurements over dynamo theory and stellar evolution to colliding winds and the stellar environment – fruitfully combine into a most interesting and still evolving overall picture, which we attempt to review here. Zeeman signatures leave no doubt that at least some O- and early B-type stars have a surface magnetic field. Indirect evidence, especially non- thermal radio emission from colliding winds, suggests many more. The emerging picture for massive stars shows similarities with results from intermediate mass stars, for which much more data are available. Observations are often compatible with a dipole or low order multi-pole field of about 1 kG (O-stars) or 300 G to 30 kG (Ap / Bp stars). Weak and unordered fields have been detected in the O-star ζ Ori A and in Vega, the first normal A-type star with a magnetic field. Theory offers essentially two explanations for the origin of the observed surface fields: fossil fields, particularly for strong and ordered fields, or different dynamo mechanisms, preferentially for less ordered fields. R. Walder CRAL: Centre de Recherche Astrophysique de Lyon ENS-Lyon, 46, all´ee d’Italie 69364 Lyon Cedex 07, France UMR CNRS 5574, Universit´ede Lyon E-mail: [email protected] D. -
Descriptions of Planetary and He1 Iocent R Ic Spacecraft and Investigations
NATIONAL SPACE SCIENCE DATA CENTER WORLD DATA CENTER A for ROCKETS6 AND SATELLITES 88-07 DATA CATALOG SERIES FOR SPACE SCIENCE AND APPLICATIOINS FLIGHT MISSIONS Volume 1A Descriptions of Planetary and He1iocent r ic Spacecraft and Investigations Second Edition March 1988 ~ CATEGORIES PACECRAFT USED FN THIS PLANETARY AND HELIOCENTRIC This category includes probes to the various planets of the solar system and probes designed to make measurements of the characteristics of interplanetary space. Also included are the probes that will pass out of the solar system into interstellar space. NSSDC/WDC-A-R&S 88-07 DATA CATALOG SE:RIES FOR SPACE SCIENCE AND APPLICATIONS FLIGHT MISSIONS Volume 1A DESCRIPTIONS OF P:LANETARY AND HELIOCENTRIC SPACECRAFT AND INVESTIGATIONS Edited By Winifred Sawtell Cameron Robert W. Vostreys Second Edition March 1988 National Space Science Data Center (NSSDC) / World Data Center A for Rc'ckets and Satellites (WDC-A-R&S National Aeronautics and Space Administration Goddard Space Flight Center Greenbelt, Maryland 20771 PREFACE TO THE SECOND EDITION The decision to reprint Volume 1A of the Data Catalog Series for Space Science and Applications Flight Missions was made primarily because it was no longer available when its companion, Volume lB, was completed in April 1987. Although Volume 1A was printed in September 1982, in this second edition no changes were made to the original text, since it described spacecraft and experiments as they actually were durin~qthe acquisition of the data in Volume 1B‘. The only significantarevisionmade in the second edition was the addition of Appendix E, which is an index showing the pages in Volume 1A where one can find descriptions of the spacecraft and experiments corresponding to the data sets described in Volume 1B. -
Annual Report 2003
Research Institute Leiden Observatory (Onderzoekinstituut Sterrewacht Leiden) Annual Report 2003 Sterrewacht Leiden Sterrewacht Leiden Faculty of Mathematics and Natural Sciences University of Leiden Niels Bohrweg 2 Postbus 9513 2333 CA Leiden 2300 RA Leiden The Netherlands http://www.strw.leidenuniv.nl Front cover: True-colour JHKs image of Centaurus A, obtained with SOFI on the ESO NTT by Van der Werf and Menende´ z-Delmestre (see section 2.6.4). An electronic version of this annual report is available on the web at http://www.strw.LeidenUniv.nl/research/annrep.php Production Annual Report 2003: F. P. Israel, J. Lub, L. Snijders, D. Schnitzeler, L. van der Veld Sterrewacht Leiden Executive (Directie) Director of Research P. T. de Zeeuw Wetenschappelijk Directeur Director of Education M. Franx Onderwijs Directeur Executive Secretary J. Lub Secretaris Instituut Supervisory Council (Raad van Toezicht) Prof. Dr. H. van der Laan (Chair) Prof. Dr. A. J. Berkhout P. Morley, M. Sc. Prof. Dr. C. J. Oort Drs. P. H. Schoute Sterrewacht Leiden Contents Part I 1 Chapter 1 1 Review of major events 3 2 Research 9 2.1 Solar System . 9 2.2 Stars . 11 2.3 Protostars and Circumstellar Disks . 13 2.4 Interstellar Medium . 20 2.5 Galactic Structure . 22 2.6 Gas and Dust in Nearby Galaxies . 23 2.7 Structure and Kinematics of Elliptical Galaxies . 30 2.8 Active Galaxies and Quasars . 34 2.9 Clusters and Cluster Galaxies . 34 2.10 Distant Objects and Large-Scale Structure . 37 2.11 Models and Theory . 43 2.12 Raymond & Beverly Sackler Lab. -
Magellanic Cloud WC/WO Wolf–Rayet Stars
Mon. Not. R. Astron. Soc. 324, 18±32 82001) Magellanic Cloud WC/WO Wolf±Rayet stars ± I. Binary frequency and Roche lobe overflow formation P. Bartzakos,1w A. F. J. Moffat1²³ and V. S. Niemela2³§ 1DeÂpartement de physique, Universite de MontreÂal, and Observatoire du Mont-MeÂgantic, PO Box 6128, Station Centre-Ville, MontreÂal, QueÂbec, H3C 3J7, Canada 2Facultad de Ciencias AstronoÂmicas y GeofõÂsicas, Universidad Nacional de La Plata, Paseo del Bosque, 1900 La Plata, Argentina Accepted 2000 October 2. Received 2000 September 18; in original form 1999 July 28 Downloaded from https://academic.oup.com/mnras/article/324/1/18/1411224 by guest on 21 April 2021 ABSTRACT A nearly complete sample of 24 Magellanic Cloud WC/WO subclass Wolf±Rayet stars is studied spectroscopically and photometrically to determine its binary frequency. Theory predicts the Roche lobe overflow produced Wolf±Rayet binary frequency to be 52 ^ 14 per cent in the Large Magellanic Cloud and 100 per cent in the Small Magellanic Cloud, not counting non-Roche lobe overflow Wolf±Rayet binaries. Lower ambient metallicity 8Z) leads to lower opacity, preventing all but the most massive 8hence luminous) single stars from reaching the Wolf±Rayet stage. However, theory predicts that Roche lobe overflow even in binaries of modest mass will lead to Wolf±Rayet stars in binaries with periods below approximately 200 d, for initial periods below approximately 1000 d, independent of Z.By examining their absolute continuum magnitudes, radial velocity variations, emission-line equivalent widths and full widths at half-maximum, a WC/WO binary frequency of only 13 per cent, significantly lower than the prediction, is found in the Large Magellanic Cloud. -
Clumping in the Winds of Wolf-Rayet Stars
Draft version September 23, 2020 A Typeset using L TEX default style in AASTeX62 Clumping in the Winds of Wolf-Rayet Stars Andre-Nicolas´ Chene´,1 Nicole St-Louis,2 Anthony F. J. Moffat,2 and Kenneth G. Gayley3 1Gemini Observatory/NSFs NOIRLab, 670 N. A‘ohoku Place, Hilo, Hawai‘i, 96720, USA 2D´epartement de Physique, Universit´ede Montr´eal, C. P. 6128, succ. centre-ville, Montr´eal (Qc) H3C 3J7, and Centre de Recherche en Astrophysique du Qu´ebec, Canada 3Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA Submitted to ApJ ABSTRACT We attempt to determine the driver for clumping in hot-star winds by extending the measure of the spectral variability level of Galactic Wolf-Rayet stars to by far the hottest known among them, the WN2 star WR 2 and the WO2 stars WR 102 and WR 142. These three stars have T⋆ = 140 kK and 200 kK, the last two being well above the bulk of WR stars with T⋆ ∼ 40 – 120 kK. This full temperature range for WR stars is much broader than that of their O-star progenitors (∼30-50 kK), so is better suited to look for any temperature dependence of wind clumping. We have obtained multiple observations with high signal-to-noise, moderate-resolution spectroscopy in search of small- scale variability in the strong emission lines from the dense winds of these three extreme stars, and find a very low-level of variability in both stars. Temperature and terminal velocity are correlated, so faster winds show a lower variability, though this trend goes against any predictions made involving Line Deshadowing Instability (LDI) only, implying that instabilities intrinsic to LDI are not the main source of wind clumping.