Universe of Binaries, Binaries in the Universe
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Rotation Period and Magnetic Field Morphology of the White Dwarf WD
A&A 439, 1099–1106 (2005) Astronomy DOI: 10.1051/0004-6361:20052642 & c ESO 2005 Astrophysics Rotation period and magnetic field morphology of the white dwarf WD 0009+501 G. Valyavin1,2, S. Bagnulo3, D. Monin4, S. Fabrika2,B.-C.Lee1, G. Galazutdinov1,2,G.A.Wade5, and T. Burlakova2 1 Korea Astronomy and Space Science institute, 61-1, Whaam-Dong, Youseong-Gu, Taejeon 305-348, Republic of Korea e-mail: [email protected] 2 Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnii Arkhyz, Karachai Cherkess Republic 357147, Russia 3 European Southern Observatory, Alonso de Cordova 3107, Santiago, Chile 4 Département de Physique et d’Astronomie, Université de Moncton, Moncton, NB, E1A 3E9, Canada 5 Department of Physics, Royal Military College of Canada, PO Box 17000 Stn “FORCES”, Kingston, Ontario, K7K 7B4, Canada Received 5 January 2005 / Accepted 8 May 2005 Abstract. We present new spectropolarimetric observations of the weak-field magnetic white dwarf WD 0009+501. From these data we estimate that the star’s longitudinal magnetic field varies with the rotation phase from about −120 kG to about +50 kG, and that the surface magnetic field varies from about 150 kG to about 300 kG. Earlier estimates of the stellar rotation period are revised anew, and we find that the most probable period is about 8 h. We have attempted to recover the star’s magnetic morphology by modelling the available magnetic observables, assuming that the field is described by the superposition of a dipole and a quadrupole. According to the best-fit model, the inclination of the rotation axis with respect to the line of sight is i = 60◦ ± 20◦, and the angle between the rotation axis and the dipolar axis is β = 111◦ ± 17◦. -
Photometry and Spectroscopy of the Luminous Red Nova PSNJ14021678+5426205 in the Galaxy M101
CORE Metadata, citation and similar papers at core.ac.uk Provided by Kazan Federal University Digital Repository Astrophysical Bulletin 2016 vol.71 N1, pages 82-94 Photometry and spectroscopy of the luminous red nova PSNJ14021678+5426205 in the galaxy M101 Goranskij V., Barsukova E., Spiridonova O., Valeev A., Fatkhullin T., Moskvitin A., Vozyakova O., Cheryasov D., Safonov B., Zharova A., Hancock T. Kazan Federal University, 420008, Kremlevskaya 18, Kazan, Russia Abstract © 2016, Pleiades Publishing, Ltd.We present the results of the study of a red nova from the observations carried out with the Russian 6-m telescope (BTA) along with other telescopes of SAO RAS and SAI MSU. To investigate the nova progenitor,we used the data from the Digital Sky Survey and amateur photos available on the Internet. In the period between April 1993 and July 2014, the brightness of the progenitor gradually increased by (Formula presented.) in the V- band. At the peak of the first outburst in mid-November 2014, the star reached an absolute visual magnitude of (Formula presented.) but was discovered later, in February 2015, in a repeated outburst at the magnitude of (Formula presented.). The amplitude of the outburst was minimum among the red novae, only (Formula presented.) in V-band. The Hα emission line and the background of a cool supergiant continuum with gradually decreasing surface temperature were observed in the spectra. Such process is typical for red novae, although the object under study showed extreme parameters: maximum luminosity, maximum outburst duration, minimum outburst amplitude, unusual shape of the light curve. This event is interpreted as a massive OB star system components’merging accompanied by formation of a common envelope and then the expansion of this envelope with minimal energy losses. -
Sun – Part 19 – Magnetic Field 1
Sun – Part 19 - Magnetic field 1 Solar magnetic field Field line distortion causes sunspots Solar magnetosphere Like all stellar magnetic fields, that of the Sun is generated by the motion of the conductive plasma within it. This motion is created through convection, a form of energy transport involving physical movements of material. Field generation is believed to take place in the Sun's convective zone where the convective circulation of the conducting plasma functions like a dynamo, generating a dipolar stellar magnetic field. In the solar dynamo, the kinetic energy of the hot, highly ionised gas inside the Sun develops self-amplifying electric currents which are converted into the solar magnetic field which gives rise to solar activity. This conversion is due to a combination of differential rotation (different angular velocity of rotation at different latitudes of a gaseous body), Coriolis forces and electrical induction. These rotational effects, and the fact that electrical current distribution can be quite complicated, influence the shape of the Sun's magnetic field, both on large and local scales. In 1952, the American father and son solar astronomers Harold and Horace Babcock developed the solar magnetograph with which they made the first ever measurements of magnetic fields on the Sun's surface. Their work enabled them to develop a model which explains their extensive observations and spectrographic analysis of solar magnetic field behaviour. In this, from large distances, the Sun's magnetic field is a simple dipole, with field lines running between the poles. However, inside the Sun, the rotational effects which help create the field also distort the field lines. -
Curriculum Vitae Avishay Gal-Yam
January 27, 2017 Curriculum Vitae Avishay Gal-Yam Personal Name: Avishay Gal-Yam Current address: Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 76100 Rehovot, Israel. Telephones: home: 972-8-9464749, work: 972-8-9342063, Fax: 972-8-9344477 e-mail: [email protected] Born: March 15, 1970, Israel Family status: Married + 3 Citizenship: Israeli Education 1997-2003: Ph.D., School of Physics and Astronomy, Tel-Aviv University, Israel. Advisor: Prof. Dan Maoz 1994-1996: B.Sc., Magna Cum Laude, in Physics and Mathematics, Tel-Aviv University, Israel. (1989-1993: Military service.) Positions 2013- : Head, Physics Core Facilities Unit, Weizmann Institute of Science, Israel. 2012- : Associate Professor, Weizmann Institute of Science, Israel. 2008- : Head, Kraar Observatory Program, Weizmann Institute of Science, Israel. 2007- : Visiting Associate, California Institute of Technology. 2007-2012: Senior Scientist, Weizmann Institute of Science, Israel. 2006-2007: Postdoctoral Scholar, California Institute of Technology. 2003-2006: Hubble Postdoctoral Fellow, California Institute of Technology. 1996-2003: Physics and Mathematics Research and Teaching Assistant, Tel Aviv University. Honors and Awards 2012: Kimmel Award for Innovative Investigation. 2010: Krill Prize for Excellence in Scientific Research. 2010: Isreali Physical Society (IPS) Prize for a Young Physicist (shared with E. Nakar). 2010: German Federal Ministry of Education and Research (BMBF) ARCHES Prize. 2010: Levinson Physics Prize. 2008: The Peter and Patricia Gruber Award. 2007: European Union IRG Fellow. 2006: “Citt`adi Cefal`u"Prize. 2003: Hubble Fellow. 2002: Tel Aviv U. School of Physics and Astronomy award for outstanding achievements. 2000: Colton Fellow. 2000: Tel Aviv U. School of Physics and Astronomy research and teaching excellence award. -
Origin of Magnetic Fields in Cataclysmic Variables
Mon. Not. R. Astron. Soc. 000, 000–000 (0000) Printed 16 October 2018 (MN LATEX style file v2.2) Origin of magnetic fields in cataclysmic variables Gordon P. Briggs1, Lilia Ferrario1, Christopher A. Tout1,2,3, Dayal T. Wickramasinghe1 1Mathematical Sciences Institute, The Australian National University, ACT 0200, Australia 2Institute of Astronomy, The Observatories, Madingley Road, Cambridge CB3 0HA 3Monash Centre for Astrophysics, School of Physics and Astronomy, 10 College Walk, Monash University 3800, Australia Accepted. Received ; in original form ABSTRACT In a series of recent papers it has been proposed that high field magnetic white dwarfs are the result of close binary interaction and merging. Population synthesis calculations have shown that the origin of isolated highly magnetic white dwarfs is consistent with the stellar merging hypothesis. In this picture the observed fields are caused by an α−Ω dynamo driven by differential rotation. The strongest fields arise when the differential rotation equals the critical break up velocity and result from the merging of two stars (one of which has a degenerate core) during common envelope evolution or from the merging of two white dwarfs. We now synthesise a population of binary systems to investigate the hypothesis that the magnetic fields in the magnetic cataclysmic variables also originate during stellar interaction in the common envelope phase. Those systems that emerge from common envelope more tightly bound form the cataclysmic variables with the strongest magnetic fields. We vary the common envelope efficiency parameter and compare the results of our population syntheses with observations of magnetic cataclysmic variables. We find that common envelope interaction can explain the observed characteristics of these magnetic systems if the envelope ejection efficiency is low. -
Variable Star Section Circular No
The British Astronomical Association Variable Star Section Circular No. 176 June 2018 Office: Burlington House, Piccadilly, London W1J 0DU Contents Joint BAA-AAVSO meeting 3 From the Director 4 V392 Per (Nova Per 2018) - Gary Poyner & Robin Leadbeater 7 High-Cadence measurements of the symbiotic star V648 Car using a CMOS camera - Steve Fleming, Terry Moon and David Hoxley 9 Analysis of two semi-regular variables in Draco – Shaun Albrighton 13 V720 Cas and its close companions – David Boyd 16 Introduction to AstroImageJ photometry software – Richard Lee 20 Project Melvyn, May 2018 update – Alex Pratt 25 Eclipsing Binary news – Des Loughney 27 Summer Eclipsing Binaries – Christopher Lloyd 29 68u Herculis – David Conner 36 The BAAVSS Eclipsing Binary Programme lists – Christopher Lloyd 39 Section Publications 42 Contributing to the VSSC 42 Section Officers 43 Cover image V392 Per (Nova Per 2018) May 6.129UT iTelescope T11 120s. Martin Mobberley 2 Back to contents Joint BAA/AAVSO Meeting on Variable Stars Warwick University Saturday 7th & Sunday 8th July 2018 Following the last very successful joint meeting between the BAAVSS and the AAVSO at Cambridge in 2008, we are holding another joint meeting at Warwick University in the UK on 7-8 July 2018. This two-day meeting will include talks by Prof Giovanna Tinetti (University College London) Chemical composition of planets in our Galaxy Prof Boris Gaensicke (University of Warwick) Gaia: Transforming Stellar Astronomy Prof Tom Marsh (University of Warwick) AR Scorpii: a remarkable highly variable -
Detection of an Increasing Orbital Period in the Subdwarf B Eclipsing System NSVS 14256825 D
CORE Metadata, citation and similar papers at core.ac.uk Provided by University of the Western Cape Research Repository Mon. Not. R. Astron. Soc. 421, 3238–3241 (2012) doi:10.1111/j.1365-2966.2012.20547.x Detection of an increasing orbital period in the subdwarf B eclipsing system NSVS 14256825 D. Kilkenny1 and C. Koen2 1Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa 2Department of Statistics, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa Accepted 2012 January 12. Received 2012 January 12; in original form 2011 December 9 ABSTRACT New timings of eclipses made in 2010 and 2011 are presented for the hot subdwarf B (sdB) eclipsing binary NSVS 14256825. Composed of an sdB star and a much cooler companion, with a period near 0.1104 days, this system is very similar to the prototype sdB eclipsing binary HW Vir. The new observations show that the binary period of NSVS 14256825 is rapidly increasing at a rate of about 12 × 10−12 days orbit−1. Key words: binaries: eclipsing – stars: individual: NSVS 14256825. variables below the period gap might all have arisen from post-sdB 1 INTRODUCTION binary evolution. Close binary stars have long been useful for the determination of In the past few years, it has become clear that continuous orbital fundamental stellar parameters such as mass and radius. Double- period change is not uncommon in HW Vir type systems – very lined spectroscopic binaries enable the mass ratio of the binary close binaries which have hot subdwarf primaries and which show components to be determined, and if the inclination of the binary eclipses, a substantial reflection effect and have typical parame- orbit can be measured or reasonably constrained – as in the case ters R1 ∼ R2 ∼ 0.2R, stellar separations ∼1R and periods of an eclipsing system – then the absolute masses can be found. -
Possible Substellar Companions in Dwarf Eclipsing Binaries: SDSS J143547. 87+ 373338.5, NSVS 7826147, and NSVS 14256825
Astronomy & Astrophysics manuscript no. 39851corr ©ESO 2021 January 22, 2021 Possible substellar companions in dwarf eclipsing binaries: ? SDSS J143547.87+373338.5, NSVS 7826147, and NSVS 14256825 M. Wolf1, H. Kucákovᡠ1; 2; 3, P. Zasche1, K. Hornoch2, J. Kára1, J. Merc1; 4, and M. Zejda5 1 Astronomical Institute, Faculty of Mathematics and Physics, Charles University, V Holešovickáchˇ 2, CZ-180 00 Praha 8, Czech Republic, e-mail: [email protected] 2 Astronomical Institute, Academy of Sciences, Fricovaˇ 298, CZ-251 65 Ondrejov,ˇ Czech Republic 3 Research Centre for Theoretical Physics and Astrophysics, Institute of Physics, Silesian University in Opava, Bezrucovoˇ nám. 13, CZ-746 01 Opava, Czech Republic 4 Institute of Physics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9, 040 01 Košice, Slovakia 5 Department of Theoretical Physics and Astrophysics, Masaryk University, Kotlárskᡠ2, CZ-611 37 Brno, Czech Republic Received January 22, 2021 ABSTRACT We present the new results of our long-term observational project to detect the small variations in the orbital periods of low-mass and short-period eclipsing binaries. About 120 new precise mid-eclipse times were obtained for three relatively well-known dwarf eclipsing binaries: SDSS J143547.87+373338.5 (P = 0:126 d), NSVS 07826147 (0.162 d), and NSVS 14256825 (0.110 d). Observed- minus-calculated (O-C) diagrams of these systems were analyzed using all accurate timings, and, where possible, new parameters of the light-time effect were calculated. For the first time, we derive (or improve upon previous findings with regard to) the short orbital periods of 13 and 10 years of possible third bodies for SDSS J143547.87+373338.5 and NSVS 07826147, respectively. -
Chandra X-Ray Study Confirms That the Magnetic Standard Ap Star KQ Vel
A&A 641, L8 (2020) Astronomy https://doi.org/10.1051/0004-6361/202038214 & c ESO 2020 Astrophysics LETTER TO THE EDITOR Chandra X-ray study confirms that the magnetic standard Ap star KQ Vel hosts a neutron star companion? Lidia M. Oskinova1,2, Richard Ignace3, Paolo Leto4, and Konstantin A. Postnov5,2 1 Institute for Physics and Astronomy, University Potsdam, 14476 Potsdam, Germany e-mail: [email protected] 2 Department of Astronomy, Kazan Federal University, Kremlevskaya Str 18, Kazan, Russia 3 Department of Physics & Astronomy, East Tennessee State University, Johnson City, TN 37614, USA 4 NAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy 5 Sternberg Astronomical Institute, M.V. Lomonosov Moscow University, Universitetskij pr. 13, 119234 Moscow, Russia Received 20 April 2020 / Accepted 20 July 2020 ABSTRACT Context. KQ Vel is a peculiar A0p star with a strong surface magnetic field of about 7.5 kG. It has a slow rotational period of nearly 8 years. Bailey et al. (A&A, 575, A115) detected a binary companion of uncertain nature and suggested that it might be a neutron star or a black hole. Aims. We analyze X-ray data obtained by the Chandra telescope to ascertain information about the stellar magnetic field and/or interaction between the star and its companion. Methods. We confirm previous X-ray detections of KQ Vel with a relatively high X-ray luminosity of 2 × 1030 erg s−1. The X-ray spectra suggest the presence of hot gas at >20 MK and, possibly, of a nonthermal component. -
Libro Resumen Sea2016v55 0.Pdf
2 ...................................................................................................................................... 4 .................................................................................................. 4 ........................................................................................................... 4 PATROCINADORES .................................................................................................................... 5 RESUMEN PROGRAMA GENERAL ............................................................................................ 7 PLANO BIZKAIA ARETOA .......................................................................................................... 8 .......................................................................................... 9 CONFERENCIAS PLENARIAS ................................................................................................... 14 ............................................................................................. 19 ................................................................................................ 21 ............... 23 CIENCIAS PLANETARIAS ......................................................................................................... 25 - tarde ....................................................................................................... 25 - ............................................................................................ 28 - tarde ................................................................................................ -
Variable Star Classification and Light Curves Manual
Variable Star Classification and Light Curves An AAVSO course for the Carolyn Hurless Online Institute for Continuing Education in Astronomy (CHOICE) This is copyrighted material meant only for official enrollees in this online course. Do not share this document with others. Please do not quote from it without prior permission from the AAVSO. Table of Contents Course Description and Requirements for Completion Chapter One- 1. Introduction . What are variable stars? . The first known variable stars 2. Variable Star Names . Constellation names . Greek letters (Bayer letters) . GCVS naming scheme . Other naming conventions . Naming variable star types 3. The Main Types of variability Extrinsic . Eclipsing . Rotating . Microlensing Intrinsic . Pulsating . Eruptive . Cataclysmic . X-Ray 4. The Variability Tree Chapter Two- 1. Rotating Variables . The Sun . BY Dra stars . RS CVn stars . Rotating ellipsoidal variables 2. Eclipsing Variables . EA . EB . EW . EP . Roche Lobes 1 Chapter Three- 1. Pulsating Variables . Classical Cepheids . Type II Cepheids . RV Tau stars . Delta Sct stars . RR Lyr stars . Miras . Semi-regular stars 2. Eruptive Variables . Young Stellar Objects . T Tau stars . FUOrs . EXOrs . UXOrs . UV Cet stars . Gamma Cas stars . S Dor stars . R CrB stars Chapter Four- 1. Cataclysmic Variables . Dwarf Novae . Novae . Recurrent Novae . Magnetic CVs . Symbiotic Variables . Supernovae 2. Other Variables . Gamma-Ray Bursters . Active Galactic Nuclei 2 Course Description and Requirements for Completion This course is an overview of the types of variable stars most commonly observed by AAVSO observers. We discuss the physical processes behind what makes each type variable and how this is demonstrated in their light curves. Variable star names and nomenclature are placed in a historical context to aid in understanding today’s classification scheme. -
Martian Ice How One Neutrino Changed Astrophysics Remembering Two Former League Presidents
Published by the Astronomical League Vol. 71, No. 3 June 2019 MARTIAN ICE HOW ONE NEUTRINO 7.20.69 CHANGED ASTROPHYSICS 5YEARS REMEMBERING TWO APOLLO 11 FORMER LEAGUE PRESIDENTS ONOMY T STR O T A H G E N P I E G O Contents N P I L R E B 4 . President’s Corner ASTRONOMY DAY Join a Tour This Year! 4 . All Things Astronomical 6 . Full Steam Ahead OCTOBER 5, From 37,000 feet above the Pacific Total Eclipse Flight: Chile 7 . Night Sky Network 2019 Ocean, you’ll be high above any clouds, July 2, 2019 For a FREE 76-page Astronomy seeing up to 3¼ minutes of totality in a PAGE 4 9 . Wanderers in the Neighborhood dark sky that makes the Sun’s corona look Day Handbook full of ideas and incredibly dramatic. Our flight will de- 10 . Deep Sky Objects suggestions, go to: part from and return to Santiago, Chile. skyandtelescope.com/2019eclipseflight www.astroleague.org Click 12 . International Dark-Sky Association on "Astronomy Day” Scroll 14 . Fire & Ice: How One Neutrino down to "Free Astronomy Day African Stargazing Safari Join astronomer Stephen James ̃̃̃Changed a Field Handbook" O’Meara in wildlife-rich Botswana July 29–August 4, 2019 for evening stargazing and daytime PAGE 14 18 . Remembering Two Former For more information, contact: safari drives at three luxury field ̃̃̃Astronomical League Presidents Gary Tomlinson camps. Only 16 spaces available! Astronomy Day Coordinator Optional extension to Victoria Falls. 21 . Coming Events [email protected] skyandtelescope.com/botswana2019 22 . Gallery—Moon Shots 25 . Observing Awards Iceland Aurorae September 26–October 2, 2019 26 .