DOCSLIB.ORG

A Variability Study of the Typical Red Supergiant Antares A

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Variability Study of the Typical Red Supergiant Antares A Western University Scholarship@Western Electronic Thesis and Dissertation Repository 4-11-2013 12:00 AM A Variability Study of the Typical Red Supergiant Antares A Teznie J D Pugh The University of Western Ontario Supervisor Dr. D. F. Gray The University of Western Ontario Graduate Program in Astronomy A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Teznie J D Pugh 2013 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Physical Processes Commons, and the Stars, Interstellar Medium and the Galaxy Commons Recommended Citation Pugh, Teznie J D, "A Variability Study of the Typical Red Supergiant Antares A" (2013). Electronic Thesis and Dissertation Repository. 1190. https://ir.lib.uwo.ca/etd/1190 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. A VARIABILITY STUDY OF THE TYPICAL RED SUPERGIANT ANTARES A (Thesis format: Monograph) by Teznie Pugh Graduate Program in Astronomy A thesis submitted in partial fulfillment of the requirements for the degree of Doctorate of Philosophy The School of Graduate and Postdoctoral Studies The University of Western Ontario London, Ontario, Canada © Teznie Pugh 2013 Abstract Red giants and red supergiants have long been known to be variable. In the last 40 years many of the features of this variability have been associated with large convective cells. Unfortunately, due to the long timescales of these variations they are not well studied, with the exception of the bright M-class supergiant Betelgeuse (α Orionis, M2 Iab). Betelgeuse has been well studied both observationally and theoretically, and has many features that are well described by models of convection. It was these studies of Betelgeuse that provided the main motivation for this thesis. We ask if the dramatic motions seen in the atmospheres of Betelgeuse (Gray 2008 amongst others) are typical of red supergiants and if their variations can be described by convective motions as is the case for that enigmatic star. Sixty-five spectra of the M-class supergiant Antares A (α Scorpii A, M1.5 Iab) were obtained at the Elginfield observatory from April 2008 until July 2010. These data were combined with historical radial velocity measures, Hipparcos photometry, and AAVSO photometry. From these data we determine four scales of variability: ~7140 days, 2167 days, ~1260 days, and ~100 days. The longest of these periods is found from the AAVSO photometry and cannot be confirmed by any of the other data. A period of similar length has been reported in one previous study but no analysis was completed. A period of this length (~7140 days; 19 years) is consistent with suspected rotation rates for red supergiants, though it is also plausible that episodic dust ejection could cause such a variation. The 2167-day variation was found from historical and present radial velocity measures. Due to the shape of the radial velocity curve, and a phase shift compared to the temperature curve, we interpret this period as a pulsation or a long secondary period. The ~1260-day period found from both sets of photometry and the 100- day timescale found from our spectral analysis are both interpreted along with a handful of periods found in the literature as arising from convection. Keywords stars: convection - stars: individual (α Sco A) - stars: oscillations - stars: variables: general - techniques: spectroscopic - techniques: radial velocities ii Acknowledgments I would, first of all, like to thank my supervisor, Dr. D. F. Gray for his assistance, for his guidance, for his support, and for his inspiration. I would also like to thank Michel DeBruyne for his technical support and training at the Elginfield Observatory, without his regular maintenance my observations would not have been possible. I acknowledge with thanks the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research. For their comments and assistance in the interpretation of the data I would like to thank Gregg Wade, Jaymie Matthews and our Astonomical Journal referee. For an explanation of the convective models of Betelgeuse I would like to thank Andrea Chiavassa. Discussions with Jan Cami, John Landstreet and David Stock have also been helpful. I am grateful for the funding I received through the Western Graduate Research Scholarship, for the financial support of my fianće Darren, and to the Canadian Astronomical Society for their travel grants. My acknowledgement would not be complete without thanking the people who have aided me in maintaining my sanity: my fianće Darren for providing emotional support and taking the lead with parenting so that I could concentrate on my research; my daycare provider Alison for being my daughter’s second mum; my family for not making a fuss about my immigration to Canada; and to all my friends for putting up with me through it all and making Canada so welcoming. iii Table of Contents Abstract .......................................................................................................................... ii Acknowledgments ......................................................................................................... iii Table of Contents .......................................................................................................... iv List of Tables............................................................................................................... viii List of Figures ............................................................................................................... ix Chapter 1 .........................................................................................................................1 1 Red Giants and Supergiants ........................................................................................1 1.1 Evolution History .................................................................................................3 1.1.1 Intermediate Mass Stars (2.5M⊙ to 10M⊙) ...............................................4 1.1.2 Low Mass Stars (0.5M⊙ to 2.3M⊙) ..........................................................5 1.1.3 High Mass Stars (>10M⊙-15M⊙) .............................................................7 1.2 Stellar Winds in the Upper HR Diagram ..............................................................8 1.2.1 Driving Mechanisms .............................................................................. 10 1.3 The Red Variables.............................................................................................. 11 Chapter 2 ....................................................................................................................... 14 2 Observations of Semiregular and Irregular Variables ................................................ 14 2.1 Photometry ........................................................................................................ 14 2.1.1 Photometric Power Spectra ..................................................................... 15 2.1.2 Long Secondary Periods and Multiperiodicity ........................................ 18 2.1.3 Period-Luminosity Relations and Mode of Pulsation .............................. 19 2.2 Temperature Variations ...................................................................................... 20 2.3 Radial Velocity .................................................................................................. 21 2.4 Interferometry .................................................................................................... 21 2.5 Polarization ........................................................................................................ 24 iv 2.6 Spectral Variability ............................................................................................ 24 2.7 Photospheric Excursions .................................................................................... 24 Chapter 3 ....................................................................................................................... 27 3 Mechanisms of Variability ........................................................................................ 27 3.1 Companion Stars ................................................................................................ 27 3.2 Surface Features ................................................................................................. 28 3.2.1 Starspots ................................................................................................. 28 3.2.2 Convection Cells .................................................................................... 30 3.2.3 Binary Heating & Ellipsoidal Variability ................................................ 32 3.3 Pulsation ............................................................................................................ 32 3.3.1 Radial Modes ......................................................................................... 33 3.3.2 Nonradial Modes .................................................................................... 34 Chapter 4 ....................................................................................................................... 38 4 Observations and Reductions ...................................................................................
Load more

Recommended publications
  • Standing on the Shoulders of Giants: New Mass and Distance Estimates
    Draft version October 15, 2020 Typeset using LATEX twocolumn style in AASTeX63 Standing on the shoulders of giants: New mass and distance estimates for Betelgeuse through combined evolutionary, asteroseismic, and hydrodynamical simulations with MESA Meridith Joyce,1, 2 Shing-Chi Leung,3 Laszl´ o´ Molnar,´ 4, 5, 6 Michael Ireland,1 Chiaki Kobayashi,7, 8, 2 and Ken'ichi Nomoto8 1Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia 2ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Australia 3TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, Caltech, Pasadena, CA 91125, USA 4Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Konkoly-Thege ´ut15-17, H-1121 Budapest, Hungary 5MTA CSFK Lendulet¨ Near-Field Cosmology Research Group, Konkoly-Thege ´ut15-17, H-1121 Budapest, Hungary 6ELTE E¨otv¨os Lor´and University, Institute of Physics, Budapest, 1117, P´azm´any P´eter s´et´any 1/A 7Centre for Astrophysics Research, Department of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK 8Kavli Institute for the Physics and Mathematics of the Universe (WPI),The University of Tokyo Institutes for Advanced Study, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan (Dated: Accepted XXX. Received YYY; in original form ZZZ) ABSTRACT We conduct a rigorous examination of the nearby red supergiant Betelgeuse by drawing on the synthesis of new observational data and three different modeling techniques. Our observational results include the release of new, processed photometric measurements collected with the space-based SMEI instrument prior to Betelgeuse's recent, unprecedented dimming event.
    [Show full text]
  • KELT-14B and KELT-15B: an Independent Discovery of WASP-122B and a New Hot Jupiter
    Swarthmore College Works Physics & Astronomy Faculty Works Physics & Astronomy 5-11-2016 KELT-14b And KELT-15b: An Independent Discovery Of WASP-122b And A New Hot Jupiter J. E. Rodriguez K. D. Colón K. G. Stassun D. Wright P. A. Cargile See next page for additional authors Follow this and additional works at: https://works.swarthmore.edu/fac-physics Part of the Astrophysics and Astronomy Commons Let us know how access to these works benefits ouy Recommended Citation J. E. Rodriguez, K. D. Colón, K. G. Stassun, D. Wright, P. A. Cargile, D. Bayliss, J. Pepper, K. A. Collins, R. B. Kuhn, M. B. Lund, R. J. Siverd, G. Zhou, B. S. Gaudi, C. G. Tinney, K. Penev, T. G. Tan, C. Stockdale, I. A. Curtis, D. James, S. Udry, D. Segransan, A. Bieryla, D. W. Latham, T. G. Beatty, J. D. Eastman, G. Myers, J. Bartz, J. Bento, Eric L.N. Jensen, T. E. Oberst, and D. J. Stevens. (2016). "KELT-14b And KELT-15b: An Independent Discovery Of WASP-122b And A New Hot Jupiter". Astronomical Journal. Volume 151, Issue 6. 138 DOI: 10.3847/0004-6256/151/6/138 https://works.swarthmore.edu/fac-physics/286 This work is brought to you for free by Swarthmore College Libraries' Works. It has been accepted for inclusion in Physics & Astronomy Faculty Works by an authorized administrator of Works. For more information, please contact [email protected]. Authors J. E. Rodriguez, K. D. Colón, K. G. Stassun, D. Wright, P. A. Cargile, D. Bayliss, J. Pepper, K. A. Collins, R.
    [Show full text]
  • Ira Sprague Bowen Papers, 1940-1973
    http://oac.cdlib.org/findaid/ark:/13030/tf2p300278 No online items Inventory of the Ira Sprague Bowen Papers, 1940-1973 Processed by Ronald S. Brashear; machine-readable finding aid created by Gabriela A. Montoya Manuscripts Department The Huntington Library 1151 Oxford Road San Marino, California 91108 Phone: (626) 405-2203 Fax: (626) 449-5720 Email: [email protected] URL: http://www.huntington.org/huntingtonlibrary.aspx?id=554 © 1998 The Huntington Library. All rights reserved. Observatories of the Carnegie Institution of Washington Collection Inventory of the Ira Sprague 1 Bowen Papers, 1940-1973 Observatories of the Carnegie Institution of Washington Collection Inventory of the Ira Sprague Bowen Paper, 1940-1973 The Huntington Library San Marino, California Contact Information Manuscripts Department The Huntington Library 1151 Oxford Road San Marino, California 91108 Phone: (626) 405-2203 Fax: (626) 449-5720 Email: [email protected] URL: http://www.huntington.org/huntingtonlibrary.aspx?id=554 Processed by: Ronald S. Brashear Encoded by: Gabriela A. Montoya © 1998 The Huntington Library. All rights reserved. Descriptive Summary Title: Ira Sprague Bowen Papers, Date (inclusive): 1940-1973 Creator: Bowen, Ira Sprague Extent: Approximately 29,000 pieces in 88 boxes Repository: The Huntington Library San Marino, California 91108 Language: English. Provenance Placed on permanent deposit in the Huntington Library by the Observatories of the Carnegie Institution of Washington Collection. This was done in 1989 as part of a letter of agreement (dated November 5, 1987) between the Huntington and the Carnegie Observatories. The papers have yet to be officially accessioned. Cataloging of the papers was completed in 1989 prior to their transfer to the Huntington.
    [Show full text]
  • Plotting Variable Stars on the H-R Diagram Activity
    Pulsating Variable Stars and the Hertzsprung-Russell Diagram The Hertzsprung-Russell (H-R) Diagram: The H-R diagram is an important astronomical tool for understanding how stars evolve over time. Stellar evolution can not be studied by observing individual stars as most changes occur over millions and billions of years. Astrophysicists observe numerous stars at various stages in their evolutionary history to determine their changing properties and probable evolutionary tracks across the H-R diagram. The H-R diagram is a scatter graph of stars. When the absolute magnitude (MV) – intrinsic brightness – of stars is plotted against their surface temperature (stellar classification) the stars are not randomly distributed on the graph but are mostly restricted to a few well-defined regions. The stars within the same regions share a common set of characteristics. As the physical characteristics of a star change over its evolutionary history, its position on the H-R diagram The H-R Diagram changes also – so the H-R diagram can also be thought of as a graphical plot of stellar evolution. From the location of a star on the diagram, its luminosity, spectral type, color, temperature, mass, age, chemical composition and evolutionary history are known. Most stars are classified by surface temperature (spectral type) from hottest to coolest as follows: O B A F G K M. These categories are further subdivided into subclasses from hottest (0) to coolest (9). The hottest B stars are B0 and the coolest are B9, followed by spectral type A0. Each major spectral classification is characterized by its own unique spectra.
    [Show full text]
  • Asteroseismology with ET
    Asteroseismology with ET Erich Gaertig & Kostas D. Kokkotas Theoretical Astrophysics - University of Tübingen nice, et-wp4 meeting,september 1st-2nd, 2010 Asteroseismology with gravitational waves as a tool to probe the inner structure of NS • neutron stars build from single-fluid, normal matter Andersson, Kokkotas (1996, 1998) Benhar, Berti, Ferrari(1999) Benhar, Ferrari, Gualtieri(2004) Asteroseismology with gravitational waves as a tool to probe the inner structure of NS • neutron stars build from single-fluid, normal matter • strange stars composed of deconfined quarks NONRADIAL OSCILLATIONS OF QUARK STARS PHYSICAL REVIEW D 68, 024019 ͑2003͒ NONRADIAL OSCILLATIONS OF QUARK STARS PHYSICAL REVIEW D 68, 024019 ͑2003͒ H. SOTANI AND T. HARADA PHYSICAL REVIEW D 68, 024019 ͑2003͒ FIG. 5. The horizontal axis is the bag constant B (MeV/fmϪ3) Sotani, Harada (2004) FIG. 4. Complex frequencies of the lowest wII mode for each and the vertical axis is the f mode frequency Re(␻). The squares, stellar model except for the plot for Bϭ471.3 MeV fmϪ3, for circles, and triangles correspond to stellar models whose radiation which the second wII mode is plotted. The labels in this figure radii are fixed at 3.8, 6.0, and 8.2 km, respectively. The dotted line Benhar, Ferrari, Gualtieri, Marassicorrespond (2007) to those of the stellar models in Table I. denotes the new empirical relationship ͑4.3͒ obtained in Sec. IV between Re(␻) of the f mode and B. simple extrapolation to quark stars is not very successful. We want to construct an alternative formula for quark star mod- fixed at Rϱϭ3.8, 6.0, and 8.2 km, and the adopted bag con- els by using our numerical results for f mode QNMs, but we stants are Bϭ42.0 and 75.0 MeV fmϪ3.
    [Show full text]
  • • Classifying Stars: HR Diagram • Luminosity, Radius, and Temperature • “Vogt-Russell” Theorem • Main Sequence • Evolution on the HR Diagram
    Stars • Classifying stars: HR diagram • Luminosity, radius, and temperature • “Vogt-Russell” theorem • Main sequence • Evolution on the HR diagram Classifying stars • We now have two properties of stars that we can measure: – Luminosity – Color/surface temperature • Using these two characteristics has proved extraordinarily effective in understanding the properties of stars – the Hertzsprung- Russell (HR) diagram If we plot lots of stars on the HR diagram, they fall into groups These groups indicate types of stars, or stages in the evolution of stars Luminosity classes • Class Ia,b : Supergiant • Class II: Bright giant • Class III: Giant • Class IV: Sub-giant • Class V: Dwarf The Sun is a G2 V star Luminosity versus radius and temperature A B R = R R = 2 RSun Sun T = T T = TSun Sun Which star is more luminous? Luminosity versus radius and temperature A B R = R R = 2 RSun Sun T = T T = TSun Sun • Each cm2 of each surface emits the same amount of radiation. • The larger stars emits more radiation because it has a larger surface. It emits 4 times as much radiation. Luminosity versus radius and temperature A1 B R = RSun R = RSun T = TSun T = 2TSun Which star is more luminous? The hotter star is more luminous. Luminosity varies as T4 (Stefan-Boltzmann Law) Luminosity Law 2 4 LA = RATA 2 4 LB RBTB 1 2 If star A is 2 times as hot as star B, and the same radius, then it will be 24 = 16 times as luminous. From a star's luminosity and temperature, we can calculate the radius.
    [Show full text]
  • Mira Variables: an Informal Review
    MIRA VARIABLES: AN INFORMAL REVIEW ROBERT F. WING Astronomy Department, Ohio State University The Mira variables can be either fascinating or frustrating -- depending on whether one is content to watch them go through their changes or whether one insists on understanding them. Virtually every observable property of the Miras, including each detail of their extraordinarily complex spectra, is strongly time-dependent. Most of the changes are cyclic with a period equal to that of the light variation. It is well known, however, that the lengths of individual light cycles often differ noticeably from the star's mean period, the differences typically amounting to several percent. And if you observe Miras -- no matter what kind of observation you make -- your work is never done, because none of their observable properties repeats exactly from cycle to cycle. The structure of Mira variables can perhaps best be described as loose. They are enormous, distended stars, and it is clear that many differ- ent atmospheric layers contribute to the spectra (and photometric colors) that we observe. As we shall see, these layers can have greatly differing temperatures, and the cyclical temperature variations of the various layers are to some extent independent of one another. Here no doubt is the source of many of the apparent inconsistencies in the observational data, as well as the phase lags between light curves in different colors. But when speaking of "layers" in the atmosphere, we should remember that they merge into one another, and that layers that are spectroscopically distinct by virtue of thelrvertical motions may in fact be momentarily at the same height in the atmosphere.
    [Show full text]
  • Detecting Differential Rotation and Starspot Evolution on the M Dwarf GJ 1243 with Kepler James R
    Western Washington University Masthead Logo Western CEDAR Physics & Astronomy College of Science and Engineering 6-20-2015 Detecting Differential Rotation and Starspot Evolution on the M Dwarf GJ 1243 with Kepler James R. A. Davenport Western Washington University, [email protected] Leslie Hebb Suzanne L. Hawley Follow this and additional works at: https://cedar.wwu.edu/physicsastronomy_facpubs Part of the Stars, Interstellar Medium and the Galaxy Commons Recommended Citation Davenport, James R. A.; Hebb, Leslie; and Hawley, Suzanne L., "Detecting Differential Rotation and Starspot Evolution on the M Dwarf GJ 1243 with Kepler" (2015). Physics & Astronomy. 16. https://cedar.wwu.edu/physicsastronomy_facpubs/16 This Article is brought to you for free and open access by the College of Science and Engineering at Western CEDAR. It has been accepted for inclusion in Physics & Astronomy by an authorized administrator of Western CEDAR. For more information, please contact [email protected]. The Astrophysical Journal, 806:212 (11pp), 2015 June 20 doi:10.1088/0004-637X/806/2/212 © 2015. The American Astronomical Society. All rights reserved. DETECTING DIFFERENTIAL ROTATION AND STARSPOT EVOLUTION ON THE M DWARF GJ 1243 WITH KEPLER James R. A. Davenport1, Leslie Hebb2, and Suzanne L. Hawley1 1 Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA; [email protected] 2 Department of Physics, Hobart and William Smith Colleges, Geneva, NY 14456, USA Received 2015 March 9; accepted 2015 May 6; published 2015 June 18 ABSTRACT We present an analysis of the starspots on the active M4 dwarf GJ 1243, using 4 years of time series photometry from Kepler.
    [Show full text]
  • The Interaction of Accretion Flux with Stellar Pulsation J.C
    340 THE INTERACTION OF ACCRETION FLUX WITH STELLAR PULSATION J.C. Papaloizou J.E. Pringle The Institute of Astronomy, Cambridge, UK We consider the usual hypothesis that the short period coherent oscillations seen in cataclysmic variables are attributable to g-modes in a slowly rotating star, for details see Papaloizou and Pringle (1977). We show that this hypothesis is untenable for three main reasons: (i) the observed periods are too short for reasonable white dwarf models, (ii) the observed variability of the oscillations is too rapid and (iii) the expected rotation of the white dwarf, due to accretion, invalidates the slow rotation as­ sumption on which standard g-mode theory is based. We investigate the low frequency spectrum of a rotating pulsating star, taking the effects of rotation fully into account. In this case there are two sets of low frequency modes, the g-modes, and modes similar to Rossby waves in the Earth's atmosphere and oceans, which we designate r-modes. Typical periods for such modes are 1/m times the rotation period of the white dwarfs outer layers (m is the azimuthal wave number). We conclude that non-radial oscillations of white dwarfs can account for the properties of the oscillations seen in dwarf novae. References Papaloizou, J.C. and Pringle, J.E., 1977, Mon. Not R. Astr. Soc, in press. DISCUSSION of paper by PAPALOIZOU and PRINGLE: KIPPENHAHN: Since the vibrational stability of white dwarfs has been mentioned several times now, I would like to report on some unpublished results obtained by Lauterborn about 10 years ago.
    [Show full text]
  • The Midnight Sky: Familiar Notes on the Stars and Planets, Edward Durkin, July 15, 1869 a Good Way to Start – Find North
    The expression "dog days" refers to the period from July 3 through Aug. 11 when our brightest night star, SIRIUS (aka the dog star), rises in conjunction* with the sun. Conjunction, in astronomy, is defined as the apparent meeting or passing of two celestial bodies. TAAS Fabulous Fifty A program for those new to astronomy Friday Evening, July 20, 2018, 8:00 pm All TAAS and other new and not so new astronomers are welcome. What is the TAAS Fabulous 50 Program? It is a set of 4 meetings spread across a calendar year in which a beginner to astronomy learns to locate 50 of the most prominent night sky objects visible to the naked eye. These include stars, constellations, asterisms, and Messier objects. Methodology 1. Meeting dates for each season in year 2018 Winter Jan 19 Spring Apr 20 Summer Jul 20 Fall Oct 19 2. Locate the brightest and easiest to observe stars and associated constellations 3. Add new prominent constellations for each season Tonight’s Schedule 8:00 pm – We meet inside for a slide presentation overview of the Summer sky. 8:40 pm – View night sky outside The Midnight Sky: Familiar Notes on the Stars and Planets, Edward Durkin, July 15, 1869 A Good Way to Start – Find North Polaris North Star Polaris is about the 50th brightest star. It appears isolated making it easy to identify. Circumpolar Stars Polaris Horizon Line Albuquerque -- 35° N Circumpolar Stars Capella the Goat Star AS THE WORLD TURNS The Circle of Perpetual Apparition for Albuquerque Deneb 1 URSA MINOR 2 3 2 URSA MAJOR & Vega BIG DIPPER 1 3 Draco 4 Camelopardalis 6 4 Deneb 5 CASSIOPEIA 5 6 Cepheus Capella the Goat Star 2 3 1 Draco Ursa Minor Ursa Major 6 Camelopardalis 4 Cassiopeia 5 Cepheus Clock and Calendar A single map of the stars can show the places of the stars at different hours and months of the year in consequence of the earth’s two primary movements: Daily Clock The rotation of the earth on it's own axis amounts to 360 degrees in 24 hours, or 15 degrees per hour (360/24).
    [Show full text]
  • Communications in Asteroseismology
    Communications in Asteroseismology Volume 141 January, 2002 Editor: Michel Breger, TurkÄ enschanzstra¼e 17, A - 1180 Wien, Austria Layout and Production: Wolfgang Zima and Renate Zechner Editorial Board: Gerald Handler, Don Kurtz, Jaymie Matthews, Ennio Poretti http://www.deltascuti.net COVER ILLUSTRATION: Representation of the COROT Satellite, which is primarily devoted to under- standing the physical processes that determine the internal structure of stars, and to building an empirically tested and calibrated theory of stellar evolution. Another scienti¯c goal is to observe extrasolar planets. British Library Cataloguing in Publication data. A Catalogue record for this book is available from the British Library. All rights reserved ISBN 3-7001-3002-3 ISSN 1021-2043 Copyright °c 2002 by Austrian Academy of Sciences Vienna Contents Multiple frequencies of θ2 Tau: Comparison of ground-based and space measurements by M. Breger 4 PMS stars as COROT additional targets by M. Marconi, F. Palla and V. Ripepi 13 The study of pulsating stars from the COROT exoplanet ¯eld data by C. Aerts 20 10 Aql, a new target for COROT by L. Bigot and W. W. Weiss 26 Status of the COROT ground-based photometric activities by R. Garrido, P. Amado, A. Moya, V. Costa, A. Rolland, I. Olivares and M. J. Goupil 42 Mode identi¯cation using the exoplanetary camera by R. Garrido, A. Moya, M. J.Goupil, C. Barban, C. van't Veer-Menneret, F. Kupka and U. Heiter 48 COROT and the late stages of stellar evolution by T. Lebzelter, H. Pikall and F. Kerschbaum 51 Pulsations of Luminous Blue Variables by E.
    [Show full text]
  • POSTERS SESSION I: Atmospheres of Massive Stars
    Abstracts of Posters 25 POSTERS (Grouped by sessions in alphabetical order by first author) SESSION I: Atmospheres of Massive Stars I-1. Pulsational Seeding of Structure in a Line-Driven Stellar Wind Nurdan Anilmis & Stan Owocki, University of Delaware Massive stars often exhibit signatures of radial or non-radial pulsation, and in principal these can play a key role in seeding structure in their radiatively driven stellar wind. We have been carrying out time-dependent hydrodynamical simulations of such winds with time-variable surface brightness and lower boundary condi- tions that are intended to mimic the forms expected from stellar pulsation. We present sample results for a strong radial pulsation, using also an SEI (Sobolev with Exact Integration) line-transfer code to derive characteristic line-profile signatures of the resulting wind structure. Future work will compare these with observed signatures in a variety of specific stars known to be radial and non-radial pulsators. I-2. Wind and Photospheric Variability in Late-B Supergiants Matt Austin, University College London (UCL); Nevyana Markova, National Astronomical Observatory, Bulgaria; Raman Prinja, UCL There is currently a growing realisation that the time-variable properties of massive stars can have a funda- mental influence in the determination of key parameters. Specifically, the fact that the winds may be highly clumped and structured can lead to significant downward revision in the mass-loss rates of OB stars. While wind clumping is generally well studied in O-type stars, it is by contrast poorly understood in B stars. In this study we present the analysis of optical data of the B8 Iae star HD 199478.
    [Show full text]