Variable Star Section Circular
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Variable Stars Observer Bulletin
Amateurs' Guide to Variable Stars September-October 2013 | Issue #2 Variable Stars Observer Bulletin ISSN 2309-5539 Twenty new W Ursae Majoris-type eclipsing binaries from the Catalina Sky Survey Details for 20 new WUMa systems are presented, along with a preliminary The FU Orionis phenomenon model of the FU Orionis stars are pre-main-sequence totally eclipsing eruptive variables which appear to be a system GSC stage in the development of T Tauri 03090-00153. stars. Image: FU Orionis. Credit: ESO NSVS 5860878 = Dauban V 171 Carbon in the sky: A new Mira variable in Cygnus a few remarkable carbon stars The list of the most interesting and bright carbon stars for northern observers is presented. Right: TT Cygni. A carbon star. Credit & Copyright: H.Olofsson (Stockholm Nova Observatory) et al. Delphini 2013 Nova has reached magnitude 4.3 visual The "Heavenly Owl" on August 16 observatory: seeing above the Black Sea waterfront VS-COMPAS Project: variable stars research and data mining. More at http://vs-compas.belastro.net Variable Stars Observer Bulletin Amateurs' Guide to Variable Stars September-October 2013 | Issue #2 C O N T E N T S 04 NSVS 5860878 = Dauban V 171: a new Mira variable in Cygnus by Ivan Adamin, Siarhey Hadon A new Mira variable in the constellation of Cygnus is presented. The variability of the NSVS 5860878 source was detected in January of 2012. Lately, the object was identified as the Dauban V171. A revision is submitted to the VSX. 06 Twenty new W Ursae Majoris-type eclipsing binaries Credit: Justin Ng from the Catalina Sky Survey by Stefan Hümmerich, Klaus Bernhard, Gregor Srdoc 16 Nova Delphini 2013: a naked-eye visible flare in A short overview of eclipsing binary northern skies stars and their traditional by Andrey Prokopovich classification scheme is given, which concentrates on W Ursae Majoris On August 14, 2013 a new bright star (WUMa)-type systems. -
White Dwarf Compact Binary Model for Long Gamma-Ray Bursts
MNRAS 000, 1–5 (0000) Preprint 6 October 2018 Compiled using MNRAS LATEX style file v3.0 A Black Hole - White Dwarf Compact Binary Model for Long Gamma-ray Bursts without Supernova Association Yi-Ze Dong, Wei-Min Gu ⋆, Tong Liu, and Junfeng Wang Department of Astronomy, Xiamen University, Xiamen, Fujian 361005, China 6 October 2018 ABSTRACT Gamma-ray bursts (GRBs) are luminous and violent phenomena in the universe. Tra- ditionally, long GRBs are expected to be produced by the collapse of massive stars and associated with supernovae. However, some low-redshift long GRBs have no detection of supernova association, such as GRBs 060505, 060614 and 111005A. It is hard to classify these events convincingly according to usual classifications, and the lack of the supernova implies a non-massive star origin. We propose a new path to produce long GRBs without supernova association, the unstable and extremely violent accretion in a contact binary system consisting of a stellar-mass black hole and a white dwarf, which fills an important gap in compact binary evolution. Key words: accretion, accretion discs – stars: black holes – binaries: close gamma-ray burst: general – white dwarfs 1 INTRODUCTION X-ray binaries (UCXBs) (Nelemans & Jonker 2010) and the repeating fast radio burst (FRB 121102) (Gu et al. 2016). It is generally believed that long gamma-ray bursts (GRBs) In addition, the gravitational wave emission originating originate from the collapse of massive stars and are accom- from the merger of double BHs was detected by LIGO panied with supernovae (Woosley 1993; Woosley & Bloom (Abbott et al. 2016a,b). -
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. -
Detecting Differential Rotation and Starspot Evolution on the M Dwarf GJ 1243 with Kepler James R
Western Washington University Masthead Logo Western CEDAR Physics & Astronomy College of Science and Engineering 6-20-2015 Detecting Differential Rotation and Starspot Evolution on the M Dwarf GJ 1243 with Kepler James R. A. Davenport Western Washington University, [email protected] Leslie Hebb Suzanne L. Hawley Follow this and additional works at: https://cedar.wwu.edu/physicsastronomy_facpubs Part of the Stars, Interstellar Medium and the Galaxy Commons Recommended Citation Davenport, James R. A.; Hebb, Leslie; and Hawley, Suzanne L., "Detecting Differential Rotation and Starspot Evolution on the M Dwarf GJ 1243 with Kepler" (2015). Physics & Astronomy. 16. https://cedar.wwu.edu/physicsastronomy_facpubs/16 This Article is brought to you for free and open access by the College of Science and Engineering at Western CEDAR. It has been accepted for inclusion in Physics & Astronomy by an authorized administrator of Western CEDAR. For more information, please contact [email protected]. The Astrophysical Journal, 806:212 (11pp), 2015 June 20 doi:10.1088/0004-637X/806/2/212 © 2015. The American Astronomical Society. All rights reserved. DETECTING DIFFERENTIAL ROTATION AND STARSPOT EVOLUTION ON THE M DWARF GJ 1243 WITH KEPLER James R. A. Davenport1, Leslie Hebb2, and Suzanne L. Hawley1 1 Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA; [email protected] 2 Department of Physics, Hobart and William Smith Colleges, Geneva, NY 14456, USA Received 2015 March 9; accepted 2015 May 6; published 2015 June 18 ABSTRACT We present an analysis of the starspots on the active M4 dwarf GJ 1243, using 4 years of time series photometry from Kepler. -
Naming the Extrasolar Planets
Naming the extrasolar planets W. Lyra Max Planck Institute for Astronomy, K¨onigstuhl 17, 69177, Heidelberg, Germany [email protected] Abstract and OGLE-TR-182 b, which does not help educators convey the message that these planets are quite similar to Jupiter. Extrasolar planets are not named and are referred to only In stark contrast, the sentence“planet Apollo is a gas giant by their assigned scientific designation. The reason given like Jupiter” is heavily - yet invisibly - coated with Coper- by the IAU to not name the planets is that it is consid- nicanism. ered impractical as planets are expected to be common. I One reason given by the IAU for not considering naming advance some reasons as to why this logic is flawed, and sug- the extrasolar planets is that it is a task deemed impractical. gest names for the 403 extrasolar planet candidates known One source is quoted as having said “if planets are found to as of Oct 2009. The names follow a scheme of association occur very frequently in the Universe, a system of individual with the constellation that the host star pertains to, and names for planets might well rapidly be found equally im- therefore are mostly drawn from Roman-Greek mythology. practicable as it is for stars, as planet discoveries progress.” Other mythologies may also be used given that a suitable 1. This leads to a second argument. It is indeed impractical association is established. to name all stars. But some stars are named nonetheless. In fact, all other classes of astronomical bodies are named. -
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. -
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 -
Documentation of Northern Alta: Grammar, Texts and Glossary
Documentation of Northern Alta: grammar, texts and glossary Alexandro-Xavier García Laguía ADVERTIMENT. La consulta d’aquesta tesi queda condicionada a l’acceptació de les següents condicions d'ús: La difusió d’aquesta tesi per mitjà del servei TDX (www.tdx.cat) i a través del Dipòsit Digital de la UB (diposit.ub.edu) ha estat autoritzada pels titulars dels drets de propietat intel·lectual únicament per a usos privats emmarcats en activitats d’investigació i docència. No s’autoritza la seva reproducció amb finalitats de lucre ni la seva difusió i posada a disposició des d’un lloc aliè al servei TDX ni al Dipòsit Digital de la UB. No s’autoritza la presentació del seu contingut en una finestra o marc aliè a TDX o al Dipòsit Digital de la UB (framing). Aquesta reserva de drets afecta tant al resum de presentació de la tesi com als seus continguts. En la utilització o cita de parts de la tesi és obligat indicar el nom de la persona autora. ADVERTENCIA. La consulta de esta tesis queda condicionada a la aceptación de las siguientes condiciones de uso: La difusión de esta tesis por medio del servicio TDR (www.tdx.cat) y a través del Repositorio Digital de la UB (diposit.ub.edu) ha sido autorizada por los titulares de los derechos de propiedad intelectual únicamente para usos privados enmarcados en actividades de investigación y docencia. No se autoriza su reproducción con finalidades de lucro ni su difusión y puesta a disposición desde un sitio ajeno al servicio TDR o al Repositorio Digital de la UB. -
List of Poster Papers
List of poster papers Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.8, on 29 Sep 2021 at 04:56:15, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0074180900083601 LIST OF POSTER PAPERS Ρ 1: Christian Doppler (1803- 1853): an Austrian scientist M. Firneis Ρ 2: Austrian astronomy today: a research initiative in stellar astrophysics M. Breger, E. A. Dorß, J. Hron, K. G. Strassmeier, W. W. Weiss, if. Oberhummer, A. Hanslmeier, G. Lustig, if. J. Schober Ρ 3: The Kuffner public observatory in Vienna P. Habison, E. Krebs Ρ 4: Inclination dependence of the mean spectral line shapes of RS CVn stars as evidence for polar spots A. P. Hatzes, S. S. Vbgt, T. F. Ramseyer, A. MiscA Ρ 5: Maximum Entropy spot mapping with simultaneous geometrical and orbital parameter fitting for contact binaries P. D. Hendry Ρ 6: Doppler imaging by the Mean Information Principle S. V. Berdyugina Ρ 7: Prospects of stellar tomographic imaging S. Jsinkov Ρ 8: A new tool for measuring stellar magnetic fields J. Babei, D. Queloz, P. North, M. Mayor Ρ 9: Fourier analysis of time-variable line profiles as a tool to evaluate latitudinal differential rotation A. F. Lanza, M. Rodonö Ρ 10: The interpretation of two-dimensional Fourier analysis of line-profile series Jinxin Hao Ρ 11: On the stability of starspot modelling. I. Zs. Kövari Ρ 12: On the stability of starspot modelling. II. Counteractions between spot parameter determination and inclination Zs. -
Starspot Temperature Along the HR Diagram
Mem. S.A.It. Suppl. Vol. 9, 220 Memorie della c SAIt 2006 Supplementi Starspot temperature along the HR diagram K. Biazzo1, A. Frasca2, S. Catalano2, E. Marilli2, G. W. Henry3, and G. Tasˇ 4 1 Department of Physics and Astronomy, University of Catania, via Santa Sofia 78, 95123 Catania, e-mail: [email protected] 2 INAF - Catania Astrophysical Observatory, via S. Sofia 78, 95123 Catania, Italy 3 Tennessee State University - Center of Excellence in Information Systems, 330 10th Ave. North, Nashville, TN 37203-3401 4 Ege University Observatory - 35100 Bornova, Izmir˙ , Turkey Abstract. The photospheric temperature of active stars is affected by the presence of cool starspots. The determination of the spot configuration and, in particular, spot temperatures and sizes, is important for understanding the role of the magnetic field in blocking the convective heating flux inside starspots. It has been demonstrated that a very sensitive di- agnostic of surface temperature in late-type stars is the depth ratio of weak photospheric absorption lines (e.g. Gray & Johanson 1991, Catalano et al. 2002). We have shown that it is possible to reconstruct the distribution of the spots, along with their sizes and tempera- tures, from the application of a spot model to the light and temperature curves (Frasca et al. 2005). In this work, we present and briefly discuss results on spot sizes and temperatures for stars in various locations in the HR diagram. Key words. Stars: activity - Stars: variability - Stars: starspot 1. Introduction Table 1. Star sample. Within a large program aimed at studying the behaviour of photospheric surface inhomo- Star Sp. -
Fundamental Parameters of 4 Massive Eclipsing Binaries in Westerlund 1
Active OB stars: structure, evolution, mass loss and critical limits Proceedings IAU Symposium No. 272, 2010 c 2010 International Astronomical Union C. Neiner, G. Wade, G. Meynet & G. Peters DOI: 00.0000/X000000000000000X Fundamental Parameters of 4 Massive Eclipsing Binaries in Westerlund 1 E. Koumpia and A.Z. Bonanos † National Observatory of Athens, Institute of Astronomy & Astrophysics, I. Metaxa & Vas. Pavlou St., Palaia Penteli GR-15236 Athens, Greece [email protected], [email protected] Abstract. Westerlund 1 is one of the most massive young clusters known in the Local Group, with an age of 3-5 Myr. It contains an assortment of rare evolved massive stars, such as blue, yellow and red supergiants, Wolf-Rayet stars, a luminous blue variable, and a magnetar, as well as 4 massive eclipsing binary systems (Wddeb, Wd13, Wd36, WR77o, see Bonanos 2007). The eclipsing binaries present a rare opportunity to constrain evolutionary models of massive stars, the distance to the cluster and furthermore, to determine a dynamical lower limit for the mass of a magnetar progenitor. Wddeb, being a detached system, is of great interest as it allows determination of the masses of 2 of the most massive unevolved stars in the cluster. We have analyzed spectra of all 4 eclipsing binaries, taken in 2007-2008 with the 6.5 meter Magellan telescope at Las Campanas Observatory, Chile, and present fundamental parameters (masses, radii) for their component stars. Keywords. open clusters and associations: individual (Westerlund 1), stars: fundamental pa- rameters, stars: early-type, binaries: eclipsing, stars: Wolf-Rayet 1. Introduction Westerlund 1 (Wd1) is one of the most massive compact young star clusters known in the Local Group. -
Arxiv:1703.10181V1 [Astro-Ph.SR] 29 Mar 2017 Ordo H G.W Alteesas“E Stragglers” “Red Stars These Call We Similar Found RGB
Draft version October 15, 2018 Preprint typeset using LATEX style emulateapj v. 01/23/15 ON THE ORIGIN OF SUB-SUBGIANT STARS II: BINARY MASS TRANSFER, ENVELOPE STRIPPING, AND MAGNETIC ACTIVITY Emily Leiner1, Robert D. Mathieu1, and Aaron M. Geller2,3 Draft version October 15, 2018 ABSTRACT Sub-subgiant stars (SSGs) lie to the red of the main-sequence and fainter than the red giant branch in cluster color-magnitude diagrams (CMDs), a region not easily populated by standard stellar evo- lution pathways. While there has been speculation on what mechanisms may create these unusual stars, no well-developed theory exists to explain their origins. Here we discuss three hypotheses of SSG formation: (1) mass transfer in a binary system, (2) stripping of a subgiant’s envelope, perhaps during a dynamical encounter, and (3) reduced luminosity due to magnetic fields that lower convective efficiency and produce large star spots. Using the stellar evolution code MESA, we develop evolu- tionary tracks for each of these hypotheses, and compare the expected stellar and orbital properties of these models with six known SSGs in the two open clusters M67 and NGC 6791. All three of these mechanisms can create stars or binary systems in the SSG CMD domain. We also calculate the frequency with which each of these mechanisms may create SSG systems, and find that the magnetic field hypothesis is expected to create SSGs with the highest frequency in open clusters. Mass transfer and envelope stripping have lower expected formation frequencies, but may nevertheless create occa- sional SSGs in open clusters. They may also be important mechanisms to create SSGs in higher mass globular clusters.