A Catalogue of Potentially Bright Close Binary
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Wolf-Rayet Stars in the Small Magellanic Cloud II
A&A 591, A22 (2016) DOI: 10.1051/0004-6361/201527916 Astronomy c ESO 2016 & Astrophysics Wolf-Rayet stars in the Small Magellanic Cloud II. Analysis of the binaries T. Shenar1, R. Hainich1, H. Todt1, A. Sander1, W.-R. Hamann1, A. F. J. Moffat2, J. J. Eldridge3, H. Pablo2, L. M. Oskinova1, and N. D. Richardson4 1 Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany e-mail: [email protected] 2 Département de physique and Centre de Recherche en Astrophysique du Québec (CRAQ), Université de Montréal, CP 6128, Succ. Centre-Ville, Montréal, Québec, H3C 3J7, Canada 3 Department of Physics, University of Auckland, Private Bag, 92019 Auckland, New Zealand 4 Ritter Observatory, Department of Physics and Astronomy, The University of Toledo, Toledo, OH 43606-3390, USA Received 8 December 2015 / Accepted 30 March 2016 ABSTRACT Context. Massive Wolf-Rayet (WR) stars are evolved massive stars (Mi & 20 M ) characterized by strong mass-loss. Hypothetically, they can form either as single stars or as mass donors in close binaries. About 40% of all known WR stars are confirmed binaries, raising the question as to the impact of binarity on the WR population. Studying WR binaries is crucial in this context, and furthermore enable one to reliably derive the elusive masses of their components, making them indispensable for the study of massive stars. Aims. By performing a spectral analysis of all multiple WR systems in the Small Magellanic Cloud (SMC), we obtain the full set of stellar parameters for each individual component. -
Mathématiques Et Espace
Atelier disciplinaire AD 5 Mathématiques et Espace Anne-Cécile DHERS, Education Nationale (mathématiques) Peggy THILLET, Education Nationale (mathématiques) Yann BARSAMIAN, Education Nationale (mathématiques) Olivier BONNETON, Sciences - U (mathématiques) Cahier d'activités Activité 1 : L'HORIZON TERRESTRE ET SPATIAL Activité 2 : DENOMBREMENT D'ETOILES DANS LE CIEL ET L'UNIVERS Activité 3 : D'HIPPARCOS A BENFORD Activité 4 : OBSERVATION STATISTIQUE DES CRATERES LUNAIRES Activité 5 : DIAMETRE DES CRATERES D'IMPACT Activité 6 : LOI DE TITIUS-BODE Activité 7 : MODELISER UNE CONSTELLATION EN 3D Crédits photo : NASA / CNES L'HORIZON TERRESTRE ET SPATIAL (3 ème / 2 nde ) __________________________________________________ OBJECTIF : Détermination de la ligne d'horizon à une altitude donnée. COMPETENCES : ● Utilisation du théorème de Pythagore ● Utilisation de Google Earth pour évaluer des distances à vol d'oiseau ● Recherche personnelle de données REALISATION : Il s'agit ici de mettre en application le théorème de Pythagore mais avec une vision terrestre dans un premier temps suite à un questionnement de l'élève puis dans un second temps de réutiliser la même démarche dans le cadre spatial de la visibilité d'un satellite. Fiche élève ____________________________________________________________________________ 1. Victor Hugo a écrit dans Les Châtiments : "Les horizons aux horizons succèdent […] : on avance toujours, on n’arrive jamais ". Face à la mer, vous voyez l'horizon à perte de vue. Mais "est-ce loin, l'horizon ?". D'après toi, jusqu'à quelle distance peux-tu voir si le temps est clair ? Réponse 1 : " Sans instrument, je peux voir jusqu'à .................. km " Réponse 2 : " Avec une paire de jumelles, je peux voir jusqu'à ............... km " 2. Nous allons maintenant calculer à l'aide du théorème de Pythagore la ligne d'horizon pour une hauteur H donnée. -
Mid-Band Gravitational Wave Detection with Precision Atomic Sensors
Mid-band gravitational wave detection with precision atomic sensors Peter W. Graham Stanford Institute for Theoretical Physics, Department of Physics, Stanford University, Stanford, CA 94305 Jason M. Hogan Department of Physics, Stanford University, Stanford, CA 94305 E-mail: [email protected] Mark A. Kasevich Department of Physics, Stanford University, Stanford, CA 94305 Surjeet Rajendran Berkeley Center for Theoretical Physics, Department of Physics, University of California, Berkeley, CA 94720 Roger W. Romani Kavli Institute for Particle Astrophysics and Cosmology Department of Physics, Stanford University, Stanford, CA 94305. For the MAGIS collaboration Abstract. We assess the science reach and technical feasibility of a satellite mission based on precision atomic sensors configured to detect gravitational radiation. Conceptual advances in the past three years indicate that a two-satellite constellation with science payloads consisting of atomic sensors based on laser cooled atomic Sr can achieve scientifically interesting gravitational wave strain sensitivities in a frequency band between the LISA and LIGO detectors, roughly 30 mHz to 10 Hz. The discovery arXiv:1711.02225v1 [astro-ph.IM] 6 Nov 2017 potential of the proposed instrument ranges from from observation of new astrophysical sources (e.g. black hole and neutron star binaries) to searches for cosmological sources of stochastic gravitational radiation and searches for dark matter. Mid-band gravitational wave detection with precision atomic sensors 2 1. Overview The recent first direct detections of gravitational waves by LIGO represent the beginning of a new era in astronomy [1, 2, 3]. Gravitational wave astronomy can provide information about astrophysical systems and cosmology that is difficult or impossible to acquire by other methods. -
Arxiv:2012.09981V1 [Astro-Ph.SR] 17 Dec 2020 2 O
Contrib. Astron. Obs. Skalnat´ePleso XX, 1 { 20, (2020) DOI: to be assigned later Flare stars in nearby Galactic open clusters based on TESS data Olga Maryeva1;2, Kamil Bicz3, Caiyun Xia4, Martina Baratella5, Patrik Cechvalaˇ 6 and Krisztian Vida7 1 Astronomical Institute of the Czech Academy of Sciences 251 65 Ondˇrejov,The Czech Republic(E-mail: [email protected]) 2 Lomonosov Moscow State University, Sternberg Astronomical Institute, Universitetsky pr. 13, 119234, Moscow, Russia 3 Astronomical Institute, University of Wroc law, Kopernika 11, 51-622 Wroc law, Poland 4 Department of Theoretical Physics and Astrophysics, Faculty of Science, Masaryk University, Kotl´aˇrsk´a2, 611 37 Brno, Czech Republic 5 Dipartimento di Fisica e Astronomia Galileo Galilei, Vicolo Osservatorio 3, 35122, Padova, Italy, (E-mail: [email protected]) 6 Department of Astronomy, Physics of the Earth and Meteorology, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Mlynsk´adolina F-2, 842 48 Bratislava, Slovakia 7 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, H-1121 Budapest, Konkoly Thege Mikl´os´ut15-17, Hungary Received: September ??, 2020; Accepted: ????????? ??, 2020 Abstract. The study is devoted to search for flare stars among confirmed members of Galactic open clusters using high-cadence photometry from TESS mission. We analyzed 957 high-cadence light curves of members from 136 open clusters. As a result, 56 flare stars were found, among them 8 hot B-A type ob- jects. Of all flares, 63 % were detected in sample of cool stars (Teff < 5000 K), and 29 % { in stars of spectral type G, while 23 % in K-type stars and ap- proximately 34% of all detected flares are in M-type stars. -
A Hot Subdwarf-White Dwarf Super-Chandrasekhar Candidate
A hot subdwarf–white dwarf super-Chandrasekhar candidate supernova Ia progenitor Ingrid Pelisoli1,2*, P. Neunteufel3, S. Geier1, T. Kupfer4,5, U. Heber6, A. Irrgang6, D. Schneider6, A. Bastian1, J. van Roestel7, V. Schaffenroth1, and B. N. Barlow8 1Institut fur¨ Physik und Astronomie, Universitat¨ Potsdam, Haus 28, Karl-Liebknecht-Str. 24/25, D-14476 Potsdam-Golm, Germany 2Department of Physics, University of Warwick, Coventry, CV4 7AL, UK 3Max Planck Institut fur¨ Astrophysik, Karl-Schwarzschild-Straße 1, 85748 Garching bei Munchen¨ 4Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106, USA 5Texas Tech University, Department of Physics & Astronomy, Box 41051, 79409, Lubbock, TX, USA 6Dr. Karl Remeis-Observatory & ECAP, Astronomical Institute, Friedrich-Alexander University Erlangen-Nuremberg (FAU), Sternwartstr. 7, 96049 Bamberg, Germany 7Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA 8Department of Physics and Astronomy, High Point University, High Point, NC 27268, USA *[email protected] ABSTRACT Supernova Ia are bright explosive events that can be used to estimate cosmological distances, allowing us to study the expansion of the Universe. They are understood to result from a thermonuclear detonation in a white dwarf that formed from the exhausted core of a star more massive than the Sun. However, the possible progenitor channels leading to an explosion are a long-standing debate, limiting the precision and accuracy of supernova Ia as distance indicators. Here we present HD 265435, a binary system with an orbital period of less than a hundred minutes, consisting of a white dwarf and a hot subdwarf — a stripped core-helium burning star. -
Luminous Blue Variables
Review Luminous Blue Variables Kerstin Weis 1* and Dominik J. Bomans 1,2,3 1 Astronomical Institute, Faculty for Physics and Astronomy, Ruhr University Bochum, 44801 Bochum, Germany 2 Department Plasmas with Complex Interactions, Ruhr University Bochum, 44801 Bochum, Germany 3 Ruhr Astroparticle and Plasma Physics (RAPP) Center, 44801 Bochum, Germany Received: 29 October 2019; Accepted: 18 February 2020; Published: 29 February 2020 Abstract: Luminous Blue Variables are massive evolved stars, here we introduce this outstanding class of objects. Described are the specific characteristics, the evolutionary state and what they are connected to other phases and types of massive stars. Our current knowledge of LBVs is limited by the fact that in comparison to other stellar classes and phases only a few “true” LBVs are known. This results from the lack of a unique, fast and always reliable identification scheme for LBVs. It literally takes time to get a true classification of a LBV. In addition the short duration of the LBV phase makes it even harder to catch and identify a star as LBV. We summarize here what is known so far, give an overview of the LBV population and the list of LBV host galaxies. LBV are clearly an important and still not fully understood phase in the live of (very) massive stars, especially due to the large and time variable mass loss during the LBV phase. We like to emphasize again the problem how to clearly identify LBV and that there are more than just one type of LBVs: The giant eruption LBVs or h Car analogs and the S Dor cycle LBVs. -
The Effect of the Apsidal Motion on the Light Curve of the Close Binary HD 93205 (O3V+O8V)?
A&A 397, 921–925 (2003) Astronomy DOI: 10.1051/0004-6361:20021438 & c ESO 2003 Astrophysics The effect of the apsidal motion on the light curve of the close binary HD 93205 (O3V+O8V)? A. M. van Genderen?? Leiden Observatory, Postbus 9513, 2300 RA Leiden, The Netherlands Received 25 June 2002/Accepted 28 August 2002 Abstract. The 1982–1985 photometry (VBLUW system) of the O3V+O8V close binary HD 93205 has been rediscussed be- cause of new insights into its true nature and orbital changes. By comparing this data set with the one obtained by Antokhina et al. (2000) in 1993, and using the same ephemeris to construct the light curve in the phase diagram, the effect of the apsidal motion became obvious: a phase shift between the two light curves and a small change of the shape. A phase-locked light variationintheL passband (containing the higher Balmer lines) is clearly present in the 1982–1985 data set and is presumably due to absorption if the O8 star is seen through cooler inter-binary gas, e.g. the bow-shock between the two colliding winds. Key words. stars: variables: general – stars: binaries: close – stars: early-type – stars: individual: HD 93205 1. Introduction Sect. 2). So far only the observations in the V band relative to the comparison star were published (Papers I, IX). The phase HD 93205 (O3V+O8V) is the earliest known system for which diagrams of the 1982–1985 and 1993 data sets, the latter from an RV is known, of which the first was presented by Conti & Antokhina et al. -
14476 (Stsci Edit Number: 4, Created: Wednesday, September 7, 2016 4:28:02 PM EST) - Overview
Proposal 14476 (STScI Edit Number: 4, Created: Wednesday, September 7, 2016 4:28:02 PM EST) - Overview 14476 - A collision reversal in HD 5980 Cycle: 24, Proposal Category: GO (Availability Mode: SUPPORTED) INVESTIGATORS Name Institution E-Mail Dr. Yael Naze (PI) (ESA Member) (Contact) Universite de Liege [email protected] Dr. D. John Hillier (CoI) University of Pittsburgh [email protected] Dr. Gloria Koenigsberger (CoI) (Contact) Universidad Nacional Autonoma de Mexico (UNAM) [email protected] Dr. Julian M. Pittard (CoI) (ESA Member) University of Leeds [email protected] Dr. Michael F. Corcoran (CoI) Universities Space Research Association [email protected] Dr. Gregor Rauw (CoI) (ESA Member) Universite de Liege [email protected] VISITS Visit Targets used in Visit Configurations used in Visit Orbits Used Last Orbit Planner Run OP Current with Visit? 01 (1) HD-5980 STIS/CCD 2 07-Sep-2016 17:28:00.0 yes CCDFLAT STIS/FUV-MAMA 2 Total Orbits Used ABSTRACT HD 5980 provides a unique laboratory for studying the properties of wind-wind collisions. It contains one of only two binary systems having a WR- star in orbit with a LBV. The latter star has been observed to undergo major changes in its wind structure over the past 35 years, implying changes in the geometry and emitting conditions of the wind-wind collision region. Ten years ago, when the LBV wind was very strong, XMM observations revealed X-ray emission consistent with the shock cone wrapping around the WR component. Since then, the wind strength has significantly declined, implying that the collision shock cone may be inverting its orientation. -
Focus on Zeta Ursae Majoris - Mizar
Vol. 3 No. 2 Spring 2007 Journal of Double Star Observations Page 51 Stargazers Corner: Focus on Zeta Ursae Majoris - Mizar Jim Daley Ludwig Schupmann Observatory (LSO) New Ipswich, New Hampshire Email: [email protected] Abstract: : This is a general interest article for both the double star viewer and armchair astronomer alike. By highlighting an interesting pair, hopefully in each issue, we have a place for those who love doubles but may have little interest in the rigors of measurements and the long lists of results. Your comments about these mini-articles are welcomed. Arabs long ago named Alcor “Saidak” or “the proof” as Introduction they too used it as a test of vision. Alcor shares nearly My first view of a double star through a telescope the same space motion with Mizar and about 20 other was an inspiring sight and just as with many new stars in what is called the Ursa Major stream or observers today, the star was Mizar. As a beginning moving cluster. The Big Dipper is considered the amateur telescope maker (1951) I followed tradition closest cluster in the solar neighborhood. Alcor’s and began to use closer doubles for resolution testing apparent separation from Mizar is more than a quar- the latest homemade instrument. Visualizing the ter light year and this alone just about rules out this scale of binaries, their physical separation, Keplerian wide pair from being a physical (in a binary star motion, orbital period, component diameters and sense) system and the most recent line-of-sight dis- spectral characteristics, all things I had heard and tance measurements give a difference between them read of, seemed a bit complicated at the time and, I of about 3 light years, ending any ideas of an orbiting might add, more so now! Through the years I found pair. -
X-Ray Study of Stellar Winds with Suzaku
X-ray Study of Stellar Winds with Suzaku Yoshiaki Hyodo Department of Physics, Graduate School of Science, Kyoto University Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan [email protected] This thesis was submitted to the Department of Physics, Graduate School of Science, Kyoto University on January 5 2009 in partial fulfillment of the requirements for the degree of Doctor of Philosophy in physics. Abstract Stellar winds from massive stars play an important role for dynamical and chemical evolution of galaxies. To evaluate their effects in a galaxy scale, both the total number and the properties of massive stars should be understood. Most massive stars have soft X-ray emission, while some have additional hard emission. Although it is indicated that the binarity is important, the condition for hard X-ray production has not yet been elucidated. Also, some massive star clusters exhibit diffuse (pc scale) X-ray emission, where stellar winds may be depositing energy to the interstellar space. However, previous studies were not able to clarify the origin of the diffuse emission. It is even unclear whether the emission is physically related to the star cluster or not. The X-ray Imaging Spectrometer (XIS) on board Suzaku has a good energy resolution, a low and stable background, and a large effective area, which are suited for narrow-band surveys and spectroscopy of both point-like and extended X-ray emission. Using the XIS, we performed a very deep survey in the direction of the central region of our Galaxy and pointing observations of three well-known star forming regions in our Galaxy (M 17, the Carina Nebula, and the Arches cluster). -
Two O2ifwn6 Stars Possibly Ejected from the Massive Young Galactic
Mon. Not. R. Astron. Soc. 416, 501–508 (2011) doi:10.1111/j.1365-2966.2011.19062.x Two O2 If*/WN6 stars possibly ejected from the massive young Galactic cluster Westerlund 2 , A. Roman-Lopes,1 R. H. Barba1 2 and N. I. Morrell3 1Department of Physics, Universidad de La Serena, Benavente 980, La Serena, Chile 2Instituto de Ciencias Astronomicas, de la Tierra, y del Espacio (ICATE-CONICET), Av. Espana˜ 1512 Sur, J54202DSP San Juan, Argentina 3Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena, Chile Accepted 2011 May 12. Received 2011 May 10; in original form 2010 September 23 ABSTRACT In this paper we report the identification of two new Galactic O2 If*/WN6 stars (WR20aa and WR20c), on the outskirts of the massive young stellar cluster Westerlund 2. The morphological similarity between the near-infrared spectra of the new stars with that of WR20a and WR21a (two of the most massive binaries known to date) is remarkable, indicating that probably they are also very massive stars. New optical spectroscopic observations of WR20aa suggest an intermediate O2 If*/WN6 spectral type. Based on a mosaic made from the 3.6 µm Spitzer IRAC images of the region including part of the RCW49 complex, we studied the spatial location of the new emission line stars, finding that WR20aa and WR20c are well displaced from the centre of Westerlund 2, being placed at ≈36 pc (15.7 arcmin) and ≈58 pc (25.0 arcmin), respectively, for an assumed heliocentric distance of 8 kpc. Also, very remarkably, a radius vector connecting the two stars would intercept the Westerlund 2 cluster exactly at the place where its stellar density reaches a maximum. -
Cyclotron Radiation from Magnetic Cataclysmic Variables (Polarization, Plasmas, Magnetized, Stars, Herculis, Puppis)
Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1985 Cyclotron Radiation From Magnetic Cataclysmic Variables (Polarization, Plasmas, Magnetized, Stars, Herculis, Puppis). Paul Everett aB rrett Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Barrett, Paul Everett, "Cyclotron Radiation From Magnetic Cataclysmic Variables (Polarization, Plasmas, Magnetized, Stars, Herculis, Puppis)." (1985). LSU Historical Dissertations and Theses. 4040. https://digitalcommons.lsu.edu/gradschool_disstheses/4040 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. INFORMATION TO USERS This reproduction was made from a copy of a document sent to us for microfilming. While the most advanced technology has been used to photograph and reproduce this document, the quality of the reproduction is heavily dependent upon the quality of the material submitted. The following explanation of techniques is provided to help clarify markings or notations which may appear on this reproduction. 1.The sign or “target” for pages apparently lacking from the document photographed is “ Missing Page(s)” . If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure complete continuity. 2. When an image on the film is obliterated with a round black mark, it is an indication of either blurred copy because of movement during exposure, duplicate copy, or copyrighted materials that should not have been filmed.