ASTRONOMY and ASTROPHYSICS Eccentric Orbits of Close
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An Interferometric Study of the Post-AGB Binary 89 Herculis I
A&A 559, A111 (2013) Astronomy DOI: 10.1051/0004-6361/201321616 & c ESO 2013 Astrophysics An interferometric study of the post-AGB binary 89 Herculis I. Spatially resolving the continuum circumstellar environment at optical and near-IR wavelengths with the VLTI, NPOI, IOTA, PTI, and the CHARA Array,, M. Hillen1, T. Verhoelst1,2,H.VanWinckel1, O. Chesneau3,C.A.Hummel4, J. D. Monnier5, C. Farrington6, C. Tycner7, D. Mourard3, T. ten Brummelaar6,D.P.K.Banerjee8,andR.T.Zavala9 1 Instituut voor Sterrenkunde (IvS), KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium e-mail: [email protected] 2 Belgian Institute for Space Aeronomy, 1180 Brussels, Belgium 3 Laboratoire Lagrange, UMR7293, Univ. Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur, 06300 Nice, France 4 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany 5 University of Michigan, 941 Dennison Building, 500 Church Street, Ann Arbor, MI 48109-1090, USA 6 The CHARA Array of Georgia State University, Mt. Wilson Observatory, Mt. Wilson, CA 91023, USA 7 Department of Physics, Central Michigan University, Mt. Pleasant, MI 48859, USA 8 Physical Research Laboratory, Navrangpura, 380009 Ahmedabad, India 9 US Naval Observatory, Flagstaff Station, 10391 W. Naval Obs. Rd., Flagstaff, AZ 86001, USA Received 1 April 2013 / Accepted 25 July 2013 ABSTRACT Context. Binary post-asymptotic giant branch (post-AGB) stars are interesting laboratories to study both the evolution of binaries as well as the structure of circumstellar disks. Aims. A multiwavelength high angular resolution study of the prototypical object 89 Herculis is performed with the aim of identifying and locating the different emission components seen in the spectral energy distribution. -
VLTI Images of Circumbinary Disks Around Evolved Stars
VLTI images of circumbinary disks around evolved stars Jacques Kluskaa, Rik Claesa, Akke Corporaala, Hans Van Winckela, Javier Alcoleab, Narsireddy Anuguc, Jean-Philippe Bergerd, Dylan Bollena, Valentin Bujarrabalb, Robert Izzarde, Devika Kamathf, Stefan Krausg, Jean-Baptiste Le Bouquind, Michiel Minh, John D. Monnieri, and Hans Olofssonj aKULeuven, Celestijnenlaan 200D, 3001 Leuven (Belgium) bObservatorio Astron´omicoNacional (Spain) cUniversity of Arizone (United States) dInstitut de Plan´etologieet d'Astrophysique de Grenoble (France) eUniversity of Surrey (UK) fMacquarie University (Australia) gUniversity of Exeter (UK) hSRON Netherlands Institute for Space Research (Netherlands) iUniv. of Michigan (United States) jChalmers University of Technology (Sweden) ABSTRACT The new generation of VLTI instruments (GRAVITY, MATISSE) aims to produce routinely interferometric images to uncover the morphological complexity of different objects at high angular resolution. Image recon- struction is, however, not a fully automated process. Here we focus on a specific science case, namely the complex circumbinary environments of a subset of evolved binaries, for which interferometric imaging provides the spatial resolution required to resolve the immediate circumbinary environment. Indeed, many binaries where the main star is in the post-asymptotic giant branch (post-AGB) phase are surrounded by circumbinary disks. Those disks were first inferred from the infrared excess produced by dust. Snapshot interferometric observations in the infrared confirmed disk-like morphology and revealed high spatial complexity of the emission that the use of geometrical models could not recover without being strongly biased. Arguably, the most convincing proof of the disk-like shape of the circumbinary environment came from the first interferometric image of such a system (IRAS08544-4431) using the PIONIER instrument at the VLTI. -
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. -
The Dust Disk of HR 4049. Another Brick in the Wall
UvA-DARE (Digital Academic Repository) The dust disk of HR 4049. Another brick in the wall Dominik, C.; Dullemond, C.P.; Cami, J.; van Winckel, H. DOI 10.1051/0004-6361:20021478 Publication date 2003 Published in Astronomy & Astrophysics Link to publication Citation for published version (APA): Dominik, C., Dullemond, C. P., Cami, J., & van Winckel, H. (2003). The dust disk of HR 4049. Another brick in the wall. Astronomy & Astrophysics, 397, 595-609. https://doi.org/10.1051/0004-6361:20021478 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:26 Sep 2021 A&A 397, 595–609 (2003) Astronomy DOI: 10.1051/0004-6361:20021478 & c ESO 2003 Astrophysics The dust disk of HR 4049 Another brick in the wall C. -
Late Stages of Stellar Evolution*
Late stages of Stellar Evolution £ Joris A.D.L. Blommaert ([email protected]) Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium Jan Cami NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035, USA Ryszard Szczerba N. Copernicus Astronomical Center, Rabia´nska 8, 87-100 Toru´n, Poland Michael J. Barlow Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, U.K. Abstract. A large fraction of ISO observing time was used to study the late stages of stellar evolution. Many molecular and solid state features, including crystalline silicates and the rota- tional lines of water vapour, were detected for the first time in the spectra of (post-)AGB stars. Their analysis has greatly improved our knowledge of stellar atmospheres and circumstel- lar environments. A surprising number of objects, particularly young planetary nebulae with Wolf-Rayet central stars, were found to exhibit emission features in their ISO spectra that are characteristic of both oxygen-rich and carbon-rich dust species, while far-IR observations of the PDR around NGC 7027 led to the first detections of the rotational line spectra of CH and CH· . Received: 18 October 2004, Accepted: 2 November 2004 1. Introduction ISO (Kessler et al., 1996, Kessler et al., 2003) has been tremendously impor- tant in the study of the final stages of stellar evolution. A substantial fraction of ISO observing time was used to observe different classes of evolved stars. IRAS had already shown the strong potential to discover many evolved stars with circumstellar shells in the infrared wavelength range. -
Arxiv:Astro-Ph/0702245V1 9 Feb 2007 1 Otabbinaries Post-AGB Ewe H Ieetcasso Vle Iaislk Asta Ba Like Binaries
Baltic Astronomy, vol. 14, xxx–xxx, 2007. Post-AGB Binaries Hans Van Winckel1 1 Instituut voor Sterrenkunde, KULeuven, Celestijnenlaan 200D, 3001 Leuven(Heverlee), Belgium Received 2006 October 15; Revised ... Abstract. The specific characteristic of the SED of serendipitously discov- ered post-AGB binaries, allowed us to launch a very extensive multi-wavelength study of evolved objects, selected on the basis of very specific selection crite- ria. Those criteria were tuned to discover more stars with circumstellar dusty discs. The observational study includes radial velocity monitoring, high spec- tral resolution optical studies, infrared spectral dust studies, sub-mm bolometric observations and high spatial resolution interferometric experiments with the VLTI. In this contribution, we will review the preliminary results of this pro- gram showing that the binary rate is indeed very high. We argue that the formation of a stable circumbinary disc must play a lead role in the evolution of the systems. Key words: stars: AGB and post-AGB, stars: binaries : spectroscopic, stars: evolution, infrared: stars, stars: circumstellar matter 1. INTRODUCTION It takes a post-AGB star only about 104 years to evolve from a molecular dominated AGB photosphere up to a stage where the central star is hot enough to ionise the surrounding material. During this short transition time, the star and circumstellar envelope must undergo fundamental and rapid changes in structure, mass-loss mode and geometry, which are still badly understood. The debate on which physical mechanisms are driving the morphology changes, gained even more impetus with the finding that also resolved but cool post-AGB stars display a surprisingly wide variety in shapes and structure. -
Noao Annual Report Fy07
AURA/NOAO ANNUAL REPORT FY 2007 Submitted to the National Science Foundation September 30, 2007 Revised as Final and Submitted January 30, 2008 Emission nebula NGC6334 (Cat’s Paw Nebula): star-forming region in the constellation Scorpius. This 2007 image was taken using the Mosaic-2 imager on the Blanco 4-meter telescope at Cerro Tololo Inter- American Observatory. Intervening dust in the plane of the Milky Way galaxy reddens the colors of the nebula. Image credit: T.A. Rector/University of Alaska Anchorage, T. Abbott and NOAO/AURA/NSF NATIONAL OPTICAL ASTRONOMY OBSERVATORY NOAO ANNUAL REPORT FY 2007 Submitted to the National Science Foundation September 30, 2007 Revised as Final and Submitted January 30, 2008 TABLE OF CONTENTS EXECUTIVE SUMMARY ............................................................................................................................. 1 1 SCIENTIFIC ACTIVITIES AND FINDINGS ..................................................................................... 2 1.1 NOAO Gemini Science Center .............................................................................. 2 GNIRS Infrared Spectroscopy and the Origins of the Peculiar Hydrogen-Deficient Stars...................... 2 Supermassive Black Hole Growth and Chemical Enrichment in the Early Universe.............................. 4 1.2 Cerro Tololo Inter-American Observatory (CTIO)................................................ 5 The Nearest Stars....................................................................................................................................... -
The Electric Sun Hypothesis
Basics of astrophysics revisited. II. Mass- luminosity- rotation relation for F, A, B, O and WR class stars Edgars Alksnis [email protected] Small volume statistics show, that luminosity of bright stars is proportional to their angular momentums of rotation when certain relation between stellar mass and stellar rotation speed is reached. Cause should be outside of standard stellar model. Concept allows strengthen hypotheses of 1) fast rotation of Wolf-Rayet stars and 2) low mass central black hole of the Milky Way. Keywords: mass-luminosity relation, stellar rotation, Wolf-Rayet stars, stellar angular momentum, Sagittarius A* mass, Sagittarius A* luminosity. In previous work (Alksnis, 2017) we have shown, that in slow rotating stars stellar luminosity is proportional to spin angular momentum of the star. This allows us to see, that there in fact are no stars outside of “main sequence” within stellar classes G, K and M. METHOD We have analyzed possible connection between stellar luminosity and stellar angular momentum in samples of most known F, A, B, O and WR class stars (tables 1-5). Stellar equatorial rotation speed (vsini) was used as main parameter of stellar rotation when possible. Several diverse data for one star were averaged. Zero stellar rotation speed was considered as an error and corresponding star has been not included in sample. RESULTS 2 F class star Relative Relative Luminosity, Relative M*R *eq mass, M radius, L rotation, L R eq HATP-6 1.29 1.46 3.55 2.950 2.28 α UMi B 1.39 1.38 3.90 38.573 26.18 Alpha Fornacis 1.33 -
Arxiv:2010.09300V1 [Astro-Ph.SR] 19 Oct 2020 (10 − 10 M Yr ) That Occurs in the Form of Gas and Fundamental Process (E.G
MNRAS 000,1{16 (2015) Preprint 20 October 2020 Compiled using MNRAS LATEX style file v3.0 Long-term photospheric instabilities and envelopes dynamics in the post-AGB binary system 89 Herculis. M. Gangi,1? M. Giarrusso,2 M. Munari,3 C. Ferrara,3;4 C. Scalia,3;4 F. Leone3;4 1INAF - Osservatorio Astronomico di Roma, Via Frascati 33, I-00078 Monte Porzio Catone, Italy 2INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, I-95123 Catania, Italy 3INAF - Osservatorio Astrofisico di Catania, Via S. Sofia 78, I{95123 Catania, Italy 4Universit`adi Catania, Dipartimento di Fisica e Astronomia, Sezione Astrofisica, Via S. Sofia 78, I{95123 Catania, Italy Accepted XXX. Received YYY; in original form ZZZ ABSTRACT We present a long-term optical spectroscopic study of the post-AGB binary system 89 Herculis, with the aim to characterize the relationship between photospheric instabil- ities and dynamics in the close circumstellar environment of the system. This study is based on spectra acquired with the high-resolution Catania Astrophysical Observa- tory Spectropolarimeter and archive data, covering a time interval between 1978 and 2018. We find long-term changes in the radial velocity curve of the system, occurring mostly in amplitude, which correlate with the variability observed in the blue-shifted absorption component of the P Cygni like Ha profile. Two possible scenarios are dis- cussed. We also find strong splitting in the s-process elements of Ba ii 6141:713 A˚ and 6496:898 A˚ lines, with short-term morphological variations. A Gaussian decomposition of such profiles allows us to distinguish four shell components, two expanding and two in-falling toward the central star, which are subject to the orbital motion of the system and are not affected by the long-term instabilities. -
The MK System and the MK Process
The MK System and the MK Process * This paper is dedicated to my father, William Thomas Morgan (1877-19??). You will never know what I owe you. THE MK SYSTEM AND THE MK PROCESS W.W. MORGAN* Yerkes Observatory University of Chicago At some point one has to pass from explanation to mere description. L. WITTGENSTEIN, On Certainty Abstract. A methodology is described that permits the development of new spectral classification systems that would supplement the MK System by making possible accurate classification of Population II stars, and other eccentric categories of stellar spectra. Table of Contents INTRODUCTION THE MK PROCESS MACROSCOPIC PROPERTIES OF THE MK PROCESS THE ACT OF SPECTRAL CLASSIFICATION ACCORDING TO THE MK PROCESS FRAGMENTS OF TWO NON-MK SYSTEMS TERMINOLOGY FOR WEAK-METALLIC-LINE CLASSIFICATION SYSTEMS file:///E|/moe/HTML/Morgan/Morgan_contents.html (1 of 2) [10/15/2003 4:28:23 PM] The MK System and the MK Process AN ALTERNATIVE PROCEDURE IN SPECTRAL CLASSIFICATION SPECTRA SHOWING THE STELLAR-WIND LINE HE I 3888 FURTHER CLASSIFICATION OF CATEGORIES LIKE THE HE I 3888 "WIND-LINE" STARS GENERALITIES CONCERNING THE NATURE OF THE SUPPLEMENTARY SYSTEM SUMMARY PENDANT: MORPHOLOGY OF SPECTRAL FORMS ACKNOWLEDGEMENTS & REFERENCE file:///E|/moe/HTML/Morgan/Morgan_contents.html (2 of 2) [10/15/2003 4:28:23 PM] The MK System and the MK Process 1. INTRODUCTION This paper is based on the conviction that a greater degree of discrimination is possible in spectral classification than that now obtainable with the MK System. This is due principally to incompleteness in the system itself. The MK System furnishes a satisfactory frame of reference for stars of Population I in the solar neighborhood; but when we consider the variety of stellar spectra encountered in our galaxy and in other stellar systems we are unable to classify many stars satisfactorily from the MK standards alone. -
Annual Report 2007 ESO
ESO European Organisation for Astronomical Research in the Southern Hemisphere Annual Report 2007 ESO European Organisation for Astronomical Research in the Southern Hemisphere Annual Report 2007 presented to the Council by the Director General Prof. Tim de Zeeuw ESO is the pre-eminent intergovernmental science and technology organisation in the field of ground-based astronomy. It is supported by 13 countries: Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Further coun- tries have expressed interest in member- ship. Created in 1962, ESO provides state-of- the-art research facilities to European as- tronomers. In pursuit of this task, ESO’s activities cover a wide spectrum including the design and construction of world- class ground-based observational facili- ties for the member-state scientists, large telescope projects, design of inno- vative scientific instruments, developing new and advanced technologies, further- La Silla. ing European cooperation and carrying out European educational programmes. One of the most exciting features of the In 2007, about 1900 proposals were VLT is the possibility to use it as a giant made for the use of ESO telescopes and ESO operates the La Silla Paranal Ob- optical interferometer (VLT Interferometer more than 700 peer-reviewed papers servatory at several sites in the Atacama or VLTI). This is done by combining the based on data from ESO telescopes were Desert region of Chile. The first site is light from several of the telescopes, al- published. La Silla, a 2 400 m high mountain 600 km lowing astronomers to observe up to north of Santiago de Chile. -
Yellow Supergiant Star
Yellow supergiant star A yellow supergiant star is a star, generally of spectral type F or G, having a supergiant luminosity class (e.g. Ia or Ib). They are stars that have evolved away from the main sequence, Hypergiants expanding and becoming more luminous. Supergiants Yellow supergiants are smaller than red Bright giants supergiants; naked eye examples include Canopus and Polaris. Many of them are variable stars, Giants mostly pulsating Cepheids such as δ Cephei itself. Subgiants absolute magni- Main sequence ("dwarfs") Contents tude (MV) Subdwarfs Spectrum Red Properties White dwarfs dwarfs Variability Evolution Brown Yellow hypergiants dwarfs Hertzsprung–Russell diagram References Spectral type Spectrum Yellow supergiants generally have spectral types of F and G, although sometimes late A or early K stars are included.[1][2][3] These spectral types are characterised by hydrogen lines that are very strong in class A, weakening through F and G until they are very weak or absent in class K. Calcium H and K lines are present in late A spectra, but stronger in class F, and strongest in class G, before weakening again in cooler stars. Lines of ionised metals are strong in class A, weaker in class F and G, and absent from cooler stars. In class G, neutral metal lines are also found, along with CH molecular bands.[4] Supergiants are identified in the Yerkes spectral classification by luminosities classes Ia and Ib, with intermediates such as Iab and Ia/ab sometimes being used. These luminosity classes are assigned using spectral lines that