DOCSLIB.ORG

Download This Article in PDF Format

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Download This Article in PDF Format A&A 457, 1015–1031 (2006) Astronomy DOI: 10.1051/0004-6361:20065052 & c ESO 2006 Astrophysics The Galactic WN stars Spectral analyses with line-blanketed model atmospheres versus stellar evolution models with and without rotation W.-R. Hamann, G. Gräfener, and A. Liermann Lehrstuhl Astrophysik der Universität Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany e-mail: [email protected] Received 20 February 2006 / Accepted 6 June 2006 ABSTRACT Context. Very massive stars pass through the Wolf-Rayet (WR) stage before they finally explode. Details of their evolution have not yet been safely established, and their physics are not well understood. Their spectral analysis requires adequate model atmospheres, which have been developed step by step during the past decades and account in their recent version for line blanketing by the millions of lines from iron and iron-group elements. However, only very few WN stars have been re-analyzed by means of line-blanketed models yet. Aims. The quantitative spectral analysis of a large sample of Galactic WN stars with the most advanced generation of model atmo- spheres should provide an empirical basis for various studies about the origin, evolution, and physics of the Wolf-Rayet stars and their powerful winds. Methods. We analyze a large sample of Galactic WN stars by means of the Potsdam Wolf-Rayet (PoWR) model atmospheres, which account for iron line blanketing and clumping. The results are compared with a synthetic population, generated from the Geneva tracks for massive star evolution. Results. We obtain a homogeneous set of stellar and atmospheric parameters for the Galactic WN stars, partly revising earlier results. Conclusions. Comparing the results of our spectral analyses of the Galactic WN stars with the predictions of the Geneva evolution- ary calculations, we conclude that there is rough qualitative agreement. However, the quantitative discrepancies are still severe, and there is no preference for the tracks that account for the effects of rotation. It seems that the evolution of massive stars is still not satisfactorily understood. Key words. stars: mass-loss – stars: winds, outflows – stars: Wolf-Rayet – stars: atmospheres – stars: early-type – stars: evolution 1. Introduction of the stellar parameters. For many WN stars, a substantial re- vision of previous results can be expected. However, only very Very massive stars pass through the Wolf-Rayet (WR) stage be- γ few WN stars have been re-analyzed so far by means of line- fore they finally explode as supernovae or, possibly, -ray bursts. blanketed models (Herald et al. 2001; Marchenko et al. 2004). The WR stars are important sources of ionizing photons, mo- In the present paper we now re-analyze all Galactic WN stars mentum, and chemical elements. However, the evolution of mas- for which observed spectra are available to us. sive stars has not yet been safely established, and their physics is not well understood. The best way to analyze a larger sample of stars systemat- The empirical knowledge about WR stars is hampered by ically is first to establish “model grids”, i.e. sets of model at- difficulties with their spectral analysis. Adequate model atmo- mospheres and synthetic spectra that cover the relevant range of spheres, which account for the non-LTE physics and their super- parameters. For WN stars we have already prepared such grids of sonic expansion, have been developed step by step during the iron-line blanketed models (Hamann & Gräfener 2004), which past decades. In a previous paper we presented a comprehen- will be used in the present paper. sive analysis of the Galactic WN stars from their helium, hy- drogen, and nitrogen spectra (Hamann & Koesterke 1998, here- The main objective of analyzing the Galactic WN stars is after quoted as Paper I). The major deficiency of this generation to understand the evolution of massive stars. The empirical re- of model atmospheres was its neglect of line blanketing by the sults from our previous comprehensive analyses were in conflict millions of lines from iron and iron-group elements. Hillier & with the evolutionary calculations. However, with the applica- Miller (1998) were the first to include this important effect in tion of the more advanced models, we will revise the empirical their code cmfgen. The line-blanketed version of the Potsdam stellar parameters. Moreover, the evolutionary models have also Wolf-Rayet (PoWR) model atmosphere code became available been significantly improved recently, since the effects of stellar with Gräfener et al. (2002). rotation are now taken into account (Meynet & Maeder 2003). The improved models provide a much better fit to the ob- Hence, the question of whether stellar evolution theory still con- served spectra, and hence lead to more reliable determination flicts with the empirical stellar parameters should be reassessed. For this purpose, we use these new evolutionary tracks for gen- Figures 12 to 74 are only available in electronic form at erating synthetic stellar populations and compare them with the http://www.edpsciences.org results from our analyses of the Galactic WN sample. Article published by EDP Sciences and available at http://www.edpsciences.org/aa or http://dx.doi.org/10.1051/0004-6361:20065052 1016 W.-R. Hamann et al.: The Galactic WN stars The paper is organized as follows. In Sect. 2 we briefly char- 227 stars in total. Among them, 127 stars2 belong to the acterize the applied model atmospheres. The program stars and WN sequence considered here, while the others belong to the observational data are introduced in Sect. 3. The spectral ana- WC sequence or are of intermediate spectral type (WN/WC). lyses and their results are given in Sect. 4, together with a long Many of the WN stars in the catalog are highly reddened and list of detailed comments on individual WN stars. Our empirical therefore invisible or at least very faint in visual light. Our study results are compared with evolutionary models in Sect. 5, espe- started with 74 WN stars for which we had sufficient spectral cially by means of a population synthesis. observations at our disposal. As we restrict the present analyses to single-star spectra, well-established binaries with composed spectra (such as WR 139 alias V444 Cyg) have been omitted 2. The models from the beginning. But so far our sample still comprised many stars that have The Potsdam Wolf-Rayet (PoWR) model atmospheres (see been suspected of binarity, on more or less sound basis. We con- Hamann & Gräfener 2004, and references therein, for more de- sidered all these cases in detail, checking the literature and in- tails) are based on the “standard” assumptions (spherically sym- specting our spectral fits for indications of binarity (cf. Hamann metric, stationary mass-loss). The velocity field is pre-specified & Gräfener 2006). For 11 objects we finally conclude that they in the standard way. For the supersonic part we adopt the usual are indeed binaries, where the companion of the WN stars con- β-law, with the terminal velocity ∞ being a free parameter. The tributes more than 15% of the total light in the visual. Those exponent β is set to unity throughout this work. In the subsonic stars were excluded from the present single-star analyses. They region, the velocity field is defined such that a hydrostatic den- are marked in Table 2 as “composite spectrum”, the reasoning sity stratification is approached. given below in the “Comments on individual stars” (Sect. 4.3). The “stellar radius” R∗, which is the inner boundary of our Among the remaining 63 stars (see Table 2), which we are model atmosphere, corresponds by definition to a Rosseland op- going to analyze in the present paper, there are still four stars tical depth of 20. The “stellar temperature” T∗ is defined by the that are most likely close binaries, but the light contamina- luminosity L and the stellar radius R∗ via the Stefan-Boltzmann tion from the non-WN companion can be neglected. These law; i.e. T∗ denotes the effective temperature referring to the ra- stars are marked by the superscript b at their WR number in dius R∗. Table 2, Col. (1), indicating their possible origin from close- Wind inhomogeneities (“clumping”) are now accounted for binary evolution. Note that six stars of our present sample in a first-order approximation, assuming that optically thin (WR 28, WR 63, WR 71, WR 85, WR 94, WR 107) have not clumps fill a volume fraction fV while the interclump space is been analyzed before. void. Thus the matter density in the clumps is higher by a fac- The observational material is mostly the same as used in = −1 tor D fV , compared to an un-clumped model with the same our previous papers and as was published in our atlas of WN parameters. D = 4 is assumed throughout this paper. The Doppler spectra (see Hamann et al. 1995 for more details). These spectra velocity D, which reflects random motions on small scales (“mi- were taken at the “Deutsch-Spanisches Astronomisches Zentrum croturbulence”), is set to 100 km s−1. (DSAZ)”, Calar Alto, Spain, and at the European Southern The major improvement of the models compared to those Observatory (ESO), La Silla, Chile. For four stars (WR 6, applied in Paper I is the inclusion of line blanketing by iron and WR 22, WR 24, WR 78) we can employ high-resolution optical other iron-group elements. About 105 energy levels and 107 line spectra from the ESO archive obtained with UVES. All optical transitions between those levels are taken into account in the ap- spectra are not flux-calibrated and therefore were normalized to proximation of the “superlevel” approach. the continuum “by eye” before being compared with normalized The PoWR code was used to establish two grids of WN-type synthetic spectra.
Load more

Recommended publications
  • N O T I C E This Document Has Been Reproduced From
    N O T I C E THIS DOCUMENT HAS BEEN REPRODUCED FROM MICROFICHE. ALTHOUGH IT IS RECOGNIZED THAT CERTAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RELEASED IN THE INTEREST OF MAKING AVAILABLE AS MUCH INFORMATION AS POSSIBLE P993-198422 International Collogium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas (4th) Held at the National institute of Standards and Technology Gaithersburg, Maryland on September 14-17, 1992 (U.S.) National inst. of Standards and Technology (PL) Gaithersburg, MD Apr 93 US. DEPARTMENT OF COMMERCE Ndioul Techcical IMermeNON Service B•11G 2-10i1A2 2 MIST-1 /4 U.S. VZPARTMENT OF COMMERCE (REV. NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY M GONTSOLw1N^BENN O4" COMM 4M /. MANUSCRIPT REVIEW AND APPROVAL "KIST/ p-850 ^' THIS NSTRUCTWNS: ATTACH ORIGINAL OF FORM TO ONE (1) COPY OF MANUSCIIN IT AND SEINE TO: PUBLICATIOM OATS NUMBER PRINTED PAGES April 1993 199 HE SECRETAIIY, APPROPRIATE EDITO RIAL REVIEW BOARD. ITLE AND SUBTITLE (CITE NN PULL) 4rh International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas -- POSTER PAPERS :ONTIEACT OR GRANT NUMBER TYPE OF REPORT AND/OR PERIOD COMM UTHOR(S) (LAST %,TAME, POST NNITIAL, SECOND INITIAL) PERFORM" ORGANIZATION (CHECK (IQ ONE SOX) EDITORS XXX MIST/GAITHERSBUIIG Sugar, Jack and Leckrone, B:;vid INST/BODUM JILA BOIRDE11 "ORATORY AND DIVISION NAMES (FIRST MOST AUTHOR ONLY) Physics Laboratory/Atomic Physics Division 'PONSORING ORGANIZATION NAME AND COMPLETE ADDRESS TREET, CITY. STATE. ZNh ^y((S/ ,T AiL7A - -ASO IECOMMENDsO FOR MIST PUBLICATION JOVIAMAL OF RESEMICM (MIST JRES) CIONOGRAPK (MIST MN) LETTER CIRCULAR J. PHYS. A CHEM.
    [Show full text]
  • Arxiv:2012.11628V3 [Astro-Ph.EP] 26 Jan 2021
    manuscript submitted to JGR: Planets The Fundamental Connections Between the Solar System and Exoplanetary Science Stephen R. Kane1, Giada N. Arney2, Paul K. Byrne3, Paul A. Dalba1∗, Steven J. Desch4, Jonti Horner5, Noam R. Izenberg6, Kathleen E. Mandt6, Victoria S. Meadows7, Lynnae C. Quick8 1Department of Earth and Planetary Sciences, University of California, Riverside, CA 92521, USA 2Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 3Planetary Research Group, Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695, USA 4School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA 5Centre for Astrophysics, University of Southern Queensland, Toowoomba, QLD 4350, Australia 6Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA 7Department of Astronomy, University of Washington, Seattle, WA 98195, USA 8Planetary Geology, Geophysics and Geochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA Key Points: • Exoplanetary science is rapidly expanding towards characterization of atmospheres and interiors. • Planetary science has similarly undergone rapid expansion of understanding plan- etary processes and evolution. • Effective studies of exoplanets require models and in-situ data derived from plan- etary science observations and exploration. arXiv:2012.11628v4 [astro-ph.EP] 8 Aug 2021 ∗NSF Astronomy and Astrophysics Postdoctoral Fellow Corresponding author: Stephen R. Kane, [email protected] {1{ manuscript submitted to JGR: Planets Abstract Over the past several decades, thousands of planets have been discovered outside of our Solar System. These planets exhibit enormous diversity, and their large numbers provide a statistical opportunity to place our Solar System within the broader context of planetary structure, atmospheres, architectures, formation, and evolution.
    [Show full text]
  • Hints About the Multiplicity of WR 133 Based on Multiepoch Radio
    Astronomy & Astrophysics manuscript no. wr133final c ESO 2019 April 2, 2019 Hints about the multiplicity of WR 133 based on multiepoch radio observations M. De Becker1, N. L. Isequilla1, 2, 3, P. Benaglia2, 3 1 Space sciences, Technologies and Astrophysics Research (STAR) Institute, University of Liège, Quartier Agora, 19c, Allée du 6 Août, B5c, B-4000 Sart Tilman, Belgium 2 Instituto Argentino de Radioastronomía (CONICET;CICPBA), C.C. No 5, 1894, Villa Elisa, Argentina 3 Facultad de Ciencias Astronómicas y Geofísicas, UNLP, Paseo del Bosque s/n, 1900, La Plata, Argentina Received ; accepted ABSTRACT Several tens of massive binary systems display indirect, or even strong evidence for non-thermal radio emission, hence their particle accelerator status. These objects are referred to as particle-accelerating colliding-wind binaries (PACWBs). WR 133 is one of the shortest period Wolf-Rayet + O systems in this category, and is therefore critical to characterize the boundaries of the parameter space adequate for particle acceleration in massive binaries. Our methodology consists in analyzing JVLA observations of WR 133 at different epochs to search for compelling evidence for a phase-locked variation attributable to synchrotron emission produced in the colliding-wind region. New data obtained during two orbits reveal a steady and thermal emission spectrum, in apparent contradiction with the previous detection of non-thermal emission. The thermal nature of the radio spectrum along the 112.4-d orbit is supported by the strong free-free absorption by the dense stellar winds, and shows that the simple binary scenario cannot explain the non-thermal emission reported previously.
    [Show full text]
  • The Enigmatic WR46: a Binary Or a Pulsator in Disguise
    A&A 385, 619–631 (2002) Astronomy DOI: 10.1051/0004-6361:20020076 & c ESO 2002 Astrophysics The enigmatic WR46: A binary or a pulsator in disguise III. Interpretation P. M. Veen1,A.M.vanGenderen1, and K. A. van der Hucht2 1 Leiden Observatory, Postbus 9513, 2300 RA Leiden, The Netherlands 2 Space Research Organization Netherlands, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands Received 1 September 2000 / Accepted 5 November 2001 Abstract. Photometric and spectroscopic monitoring campaigns of WR 46 (WN3p), as presented in Veen et al. (2002a,b; hereafter Papers I and II, respectively), yield the following results. The light- and colour variations 89 91 reveal a dominant single-wave period of Psw =0.1412 d in 1989, and Psw =0.1363 d in 1991. Because of a small difference in the minima, this periodicity may be a double-wave phenomenon (Pdw). The line fluxes vary in concert with the magnitudes. The significant difference of the periods can be either due to the occurence of two distinct periods, or due to a gradual change of the periodicity. A gradual brightening of the system of 0m. 12 appeared to accompany the period change. In addition, the light variations in 1989 show strong evidence for an additional period Px =0.2304 d. Generally, the radial velocities show a cyclic variability on a time scale of the photometric double-wave. However, often they do not vary at all. The observed variability confirms the Population I WR nature of the light source, as noted independently by Marchenko et al. (2000). In the present paper, we first show how the photometric double-wave variability can be interpreted as a rotating ellipsoidal density distribution in the stellar wind.
    [Show full text]
  • [Astro-Ph.SR] 30 Jun 2016 Alschaefer Gail MNRAS Hi Farrington Chris Ebr Pablo Herbert Old Richardson D
    MNRAS 000, 1–11 (2016) Preprint 1 July 2016 Compiled using MNRAS LATEX style file v3.0 The CHARA Array resolves the long-period Wolf-Rayet binaries WR 137 and WR 138 Noel D. Richardson1⋆, Tomer Shenar2, Olivier Roy-Loubier3, Gail Schaefer4, Anthony F. J. Moffat3, Nicole St-Louis3, Douglas R. Gies5, Chris Farrington4, Grant M. Hill6, Peredur M. Williams7, Kathryn Gordon5, Herbert Pablo3, and Tahina Ramiaramanantsoa3 1 Ritter Observatory, Department of Physics and Astronomy, The University of Toledo, Toledo, OH 43606-3390, USA 2 Institut fur¨ Physik und Astronomie, Universit¨at Potsdam, Karl-Liebknecht-Str. 24/25, D-14476 Potsdam, Germany 3 D´epartement de physique and Centre de Recherche en Astrophysique du Qu´ebec (CRAQ), Universit´ede Montr´eal, C.P. 6128, Succ. Centre-Ville, Montr´eal, Qu´ebec, H3C 3J7, Canada 4 The CHARA Array, Mount Wilson Observatory, 91023 Mount Wilson CA, USA 5 Center for High Angular Resolution Astronomy, Department of Physics and Astronomy, Georgia State University, P. O. Box 5060, Atlanta, GA 30302-5060, USA 6 W. M. Keck Observatory, 65-1120 Mamalahoa Highway, Kamuela, HI 96743, USA 7 Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ, UK ABSTRACT We report on interferometric observations with the CHARA Array of two classical Wolf-Rayet stars in suspected binary systems, namely WR 137 and WR 138. In both cases, we resolve the component stars to be separated by a few milliarcseconds. The data were collected in the H-band, and provide a measure of the fractional flux for both stars in each system. We find that the WR star is the dominant H-band light source in both systems ( fWR,137 = 0.59 ± 0.04; fWR,138 = 0.67 ± 0.01), which is confirmed through both comparisons with estimated fundamental parameters for WR stars and O dwarfs, as well as through spectral modeling of each system.
    [Show full text]
  • The Multiple Spectroscopic and Photometric Periods of DI Cru
    The multiple spectroscopic and photometric periods of DI Cru ≡ WR 46 1 Alexandre S. Oliveira2, J. E. Steiner2 and M. P. Diaz2 [email protected],[email protected],[email protected] ABSTRACT In an effort to determine the orbital period of the enigmatic star DI Cru ≡ WR 46 ≡ HD 104994, we made photometric and spectroscopic observations of this object between 1996 and 2002. Both photometric and spectroscopic characteristics are quite complex. The star is highly variable on short (few hours) as well as on long (few months) time-scales. The optical spectrum is rich in strong emission lines of high ionization species such as He II, N IV, N V and O VI. Weak emission of C III and Hβ is also present. Emission lines have been compiled and identified from the ultraviolet to the infrared. In the UV, emission of O V and N IV is also observed, together with very weak emission of C IV. The N V 4603+19A/He˚ II 4686A˚ line ratios vary by a significant amount from night to night. Temporal Variance Spectrum – TVS – analysis shows that the He II 4686A˚ line has P Cyg-like variable absorption, while N V 4603/19A˚ lines have a strong and broad variable component due to the continuum fluorescence from a source (stellar atmosphere/optically thick wind) of variable temperature. We also show that the object has variable degree of ionization, probably caused by wind density variation. The star presents multiple periods in radial velocity and photometry. We derived, from our data, a main radial velocity period of 0.3319 d with an amplitude of K =58kms−1.
    [Show full text]
  • Orbital Elements of Double Stars
    Orbital elements of double stars: ADS 1548 Marco Scardia, Jean-Louis Prieur, Luigi Pansecchi, Robert Argyle, Josefina Ling, Eric Aristidi, Alessio Zanutta, Lyu Abe, Philippe Bendjoya, Jean-Pierre Rivet, et al. To cite this version: Marco Scardia, Jean-Louis Prieur, Luigi Pansecchi, Robert Argyle, Josefina Ling, et al.. Orbital elements of double stars: ADS 1548. 2018, pp.1. hal-02357208 HAL Id: hal-02357208 https://hal.archives-ouvertes.fr/hal-02357208 Submitted on 23 Nov 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. INTERNATIONAL ASTRONOMICAL UNION COMMISSION G1 (BINARY AND MULTIPLE STAR SYSTEMS) DOUBLE STARS INFORMATION CIRCULAR No. 194 (FEBRUARY 2018) NEW ORBITS ADS Name P T e Ω(2000) 2018 Author(s) α2000δ n a i ! Last ob. 2019 1548 A 819 AB 135y4 2011.06 0.548 153◦8 39◦7 000161 SCARDIA 01570+3101 2◦6587 000424 50◦5 189◦7 2017.833 49.4 0.163 et al. (*) - HDS 333 49.54 1981.14 0.60 252.6 253.8 0.542 TOKOVININ 02332-5156 7.2665 0.413 57.4 150.9 2018.073 255.7 0.519 - COU 691 61.76 1964.53 0.059 68.6 276.2 0.109 DOCOBO 03423+3141 5.8290 0.160
    [Show full text]
  • Appendix: Spectroscopy of Variable Stars
    Appendix: Spectroscopy of Variable Stars As amateur astronomers gain ever-increasing access to professional tools, the science of spectroscopy of variable stars is now within reach of the experienced variable star observer. In this section we shall examine the basic tools used to perform spectroscopy and how to use the data collected in ways that augment our understanding of variable stars. Naturally, this section cannot cover every aspect of this vast subject, and we will concentrate just on the basics of this field so that the observer can come to grips with it. It will be noticed by experienced observers that variable stars often alter their spectral characteristics as they vary in light output. Cepheid variable stars can change from G types to F types during their periods of oscillation, and young variables can change from A to B types or vice versa. Spec­ troscopy enables observers to monitor these changes if their instrumentation is sensitive enough. However, this is not an easy field of study. It requires patience and dedication and access to resources that most amateurs do not possess. Nevertheless, it is an emerging field, and should the reader wish to get involved with this type of observation know that there are some excellent guides to variable star spectroscopy via the BAA and the AAVSO. Some of the workshops run by Robin Leadbeater of the BAA Variable Star section and others such as Christian Buil are a very good introduction to the field. © Springer Nature Switzerland AG 2018 M. Griffiths, Observer’s Guide to Variable Stars, The Patrick Moore 291 Practical Astronomy Series, https://doi.org/10.1007/978-3-030-00904-5 292 Appendix: Spectroscopy of Variable Stars Spectra, Spectroscopes and Image Acquisition What are spectra, and how are they observed? The spectra we see from stars is the result of the complete output in visible light of the star (in simple terms).
    [Show full text]
  • Wolf-Rayet Stars and O-Star Runaways with HIPPARCOS II. Photometry?
    UvA-DARE (Digital Academic Repository) Wolf-Rayet stars and O-stars runaways with HIPPARCOS. II. Photometry Marchenko, S.V.; Moffat, A.F.J.; van der Hucht, K.A.; Seggewiss, W.; Schrijver, H.; Stenholm, B.; Lundstrom, I.; Setia Gunawan, D.Y.A.; Sutantyo, W.; van den Heuvel, E.P.J.; Cuyper, J.- P.; Gomez, A.E. Publication date 1998 Published in Astronomy & Astrophysics Link to publication Citation for published version (APA): Marchenko, S. V., Moffat, A. F. J., van der Hucht, K. A., Seggewiss, W., Schrijver, H., Stenholm, B., Lundstrom, I., Setia Gunawan, D. Y. A., Sutantyo, W., van den Heuvel, E. P. J., Cuyper, J-P., & Gomez, A. E. (1998). Wolf-Rayet stars and O-stars runaways with HIPPARCOS. II. Photometry. Astronomy & Astrophysics, 331, 1022-1036. General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:30 Sep 2021 Astron.
    [Show full text]
  • International Astronomical Union Commission G1 BIBLIOGRAPHY
    International Astronomical Union Commission G1 BIBLIOGRAPHY OF CLOSE BINARIES No. 108 Editor-in-Chief: W. Van Hamme Editors: R.H. Barb´a D.R. Faulkner P.G. Niarchos D. Nogami R.G. Samec C.D. Scarfe C.A. Tout M. Wolf M. Zejda Material published by March 15, 2019 BCB issues are available at the following URLs: http://ad.usno.navy.mil/wds/bsl/G1_bcb_page.html, http://faculty.fiu.edu/~vanhamme/IAU-BCB/. The bibliographical entries for Individual Stars and Collections of Data, as well as a few General entries, are categorized according to the following coding scheme. Data from archives or databases, or previously published, are identified with an asterisk. The observation codes in the first four groups may be followed by one of the following wavelength codes. g. γ-ray. i. infrared. m. microwave. o. optical r. radio u. ultraviolet x. x-ray 1. Photometric data a. CCD b. Photoelectric c. Photographic d. Visual 2. Spectroscopic data a. Radial velocities b. Spectral classification c. Line identification d. Spectrophotometry 3. Polarimetry a. Broad-band b. Spectropolarimetry 4. Astrometry a. Positions and proper motions b. Relative positions only c. Interferometry 5. Derived results a. Times of minima b. New or improved ephemeris, period variations c. Parameters derivable from light curves d. Elements derivable from velocity curves e. Absolute dimensions, masses f. Apsidal motion and structure constants g. Physical properties of stellar atmospheres h. Chemical abundances i. Accretion disks and accretion phenomena j. Mass loss and mass exchange k. Rotational velocities 6. Catalogues, discoveries, charts a. Catalogues b. Discoveries of new binaries and novae c.
    [Show full text]
  • Université De Montréal Étude De L'étoile Wolf-Rayet Variable WR 46 Dans L'ultraviolet Lointain Et Les Rayons X Par Vince
    Université de Montréal Étude de l’étoile Wolf-Rayet variable WR 46 dans l’ultraviolet lointain et les rayons X par Vincent Hénault-Brunet Département de physique Faculté des arts et des sciences Mémoire présenté à la Faculté des études supérieures en vue de l’obtention du grade de Maître ès sciences (M.Sc.) en physique Août, 2009 c Vincent Hénault-Brunet, 2009 ! Université de Montréal Faculté des études supérieures Ce mémoire intitulé: Étude de l’étoile Wolf-Rayet variable WR 46 dans l’ultraviolet lointain et les rayons X présenté par: Vincent Hénault-Brunet a été évalué par un jury composé des personnes suivantes: Pierre Bergeron, président-rapporteur Nicole St-Louis, directrice de recherche Claude Carignan, membre du jury Mémoire accepté le: 11 septembre 2009 i «Il me semble que ce qui est requis est un délicat équilibre entre deux tendances : celle qui nous pousse à scruter de manière inlassablement sceptique toutes les hypothèses qui nous sont soumises et celle qui nous invite à garder une grande ouverture aux idées nouvelles.» - Carl Sagan ii Sommaire L’étoile Wolf-Rayet WR 46 est connue pour sa variabilité complexe sur des échelles de temps relativement courtes de quelques heures et sur des échelles de temps plus longues de plusieurs mois. Des décalages périodiques mais intermittents en vitesse radiale ont déjà été observés dans ses raies d’émission optiques. Plusieurs périodes photométriques ont aussi été mesurées dans le passé. Des pulsations non-radiales, une modulation liée à la rotation rapide, ou encore la présence d’un compagnon de faible masse dont la présence reste à confirmer ont été proposées pour expliquer le comportement de l’étoile sur des échelles de temps de quelques heures.
    [Show full text]
  • First Dynamical Mass of a Nitrogen Rich Wolf Rayet Star
    The CHARA Science Meeting 2021 The First Dynamical Mass Determination of a Nitrogen-rich Wolf– Rayet Star Using a Combined Visual and Spectroscopic Orbit Noel Richardson, Laura Lee, et al. Embry-Riddle Aeronautical University 1 The CHARA Science Meeting 2021 What is a Wolf-Rayet star? • Classical WR stars are H-free, evolved massive stars. They have extremely high effective temperatures and strong stellar winds. WR124, HST Sana et al. (2012) 2 The CHARA Science Meeting 2021 Previous Interferometry of WR stars • Due to the rarity of these objects, only a few have been observed. • Large distances – not much to resolve for most WR stars • Binaries are main focus with current instrumentation 3 The CHARA Science Meeting 2021 Gamma2 Vel • WC8 + O7.5III • P = 78.53 d • e = 0.33 • Lamberts et al. 2017 + RiChardson et al. 2017 • M_O = 28.4 Msun • M_WR = 9 Msun 4 The CHARA Science Meeting 2021 WR140 – Monnier et al. (2011); Thomas, Richardson et al. (submitted) • WC7pd + O5.5fC • P = 7.93 years • e = 0.8993 • M_O = 29.3 Msun • M_WR = 10.3 Msun 5 The CHARA Science Meeting 2021 WR137, WR138 – resolved with CHARA (Richardson et al. 2016) • WR 137 • WC7 + O • P = 13 yr • Dust formation at periastron • WR 138 • WN + O • P – unknown, possibly ~4 yr? • CLIMB observations resolved the binaries – began a long-term NOAO NOIR Lab program for orbits. • Upgraded MIRC-X made the program finally take off! 6 The CHARA Science Meeting 2021 WR 133 - background • WN5o + O9I • Known SB2 orbit with P=133 d, but relatively understudied. • member of NGC 6871 • Inclination
    [Show full text]