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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. -
Multi-Periodic Photospheric Pulsations and Connected Wind Structures in HD 64760
A&A 447, 325–341 (2006) Astronomy DOI: 10.1051/0004-6361:20053847 & c ESO 2006 Astrophysics Multi-periodic photospheric pulsations and connected wind structures in HD 64760 A. Kaufer1,O.Stahl2,R.K.Prinja3, and D. Witherick3, 1 European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Santiago 19, Chile e-mail: [email protected] 2 Landessternwarte Heidelberg, Königstuhl 12, 69117 Heidelberg, Germany 3 Department of Physics & Astronomy, University College London, Gower Street, London, WC1E 6BT, UK Received 18 July 2005 / Accepted 17 October 2005 ABSTRACT We report on the results of an extended optical spectroscopic monitoring campaign on the early-type B supergiant HD 64760 (B0.5 Ib) designed to probe the deep-seated origin of spatial wind structure in massive stars. This new study is based on high-resolution echelle spectra obtained with the Feros instrument at ESO La Silla. 279 spectra were collected over 10 nights between February 14 and 24, 2003. From the period analysis of the line-profile variability of the photospheric lines we identify three closely spaced periods around 4.810 h and a splitting of ±3%. The velocity – phase diagrams of the line-profile variations for the distinct periods reveal characteristic prograde non-radial pulsation patterns of high order corresponding to pulsation modes with l and m in the range 6−10. A detailed modeling of the multi-periodic non-radial pulsations with the Bruce and Kylie pulsation-model codes (Townsend 1997b, MNRAS, 284, 839) favors either three modes with l = −m and l = 8, 6, 8 or m = −6andl = 8, 6, 10 with the second case maintaining the closely spaced periods in the co-rotating frame. -
POSTERS SESSION I: Atmospheres of Massive Stars
Abstracts of Posters 25 POSTERS (Grouped by sessions in alphabetical order by first author) SESSION I: Atmospheres of Massive Stars I-1. Pulsational Seeding of Structure in a Line-Driven Stellar Wind Nurdan Anilmis & Stan Owocki, University of Delaware Massive stars often exhibit signatures of radial or non-radial pulsation, and in principal these can play a key role in seeding structure in their radiatively driven stellar wind. We have been carrying out time-dependent hydrodynamical simulations of such winds with time-variable surface brightness and lower boundary condi- tions that are intended to mimic the forms expected from stellar pulsation. We present sample results for a strong radial pulsation, using also an SEI (Sobolev with Exact Integration) line-transfer code to derive characteristic line-profile signatures of the resulting wind structure. Future work will compare these with observed signatures in a variety of specific stars known to be radial and non-radial pulsators. I-2. Wind and Photospheric Variability in Late-B Supergiants Matt Austin, University College London (UCL); Nevyana Markova, National Astronomical Observatory, Bulgaria; Raman Prinja, UCL There is currently a growing realisation that the time-variable properties of massive stars can have a funda- mental influence in the determination of key parameters. Specifically, the fact that the winds may be highly clumped and structured can lead to significant downward revision in the mass-loss rates of OB stars. While wind clumping is generally well studied in O-type stars, it is by contrast poorly understood in B stars. In this study we present the analysis of optical data of the B8 Iae star HD 199478. -
A 2.4-12 Microns Spectrophotometric Study with ISO of Cygnus X-3 in Quiescence
1 Abstract. We present mid-infrared spectrophotometric results obtained with the ISO on the peculiar X-ray bi- nary Cygnus X-3 in quiescence, at orbital phases 0.83 to 1.04. The 2.4 - 12 µm continuum radiation observed with ISOPHOT-S can be explained by thermal free-free emis- sion in an expanding wind with, above 6.5 µm, a possi- ble additional black-body component with temperature T ∼ 250K and radius R ∼ 5000R⊙ at 10 kpc, likely due to thermal emission by circumstellar dust. The observed brightness and continuum spectrum closely match that of the Wolf-Rayet star WR 147, a WN8+B0.5 binary system, when rescaled at the same 10 kpc distance as Cygnus X- 3. A rough mass loss estimate assuming a WN wind gives −4 −1 ∼ 1.2 × 10 M⊙.yr . A line at ∼ 4.3 µm with a more than 4.3 σ detection level, and with a dereddened flux of 126 mJy, is interpreted as the expected He I 3p-3s line at 4.295 µm, a prominent line in the WR 147 spectrum. These results are consistent with a Wolf-Rayet-like com- panion to the compact object in Cyg X-3 of WN8 type, a later type than suggested by earlier works. Key words: binaries: close - stars: individual: Cyg X-3 - stars: Wolf-Rayet - stars: mass loss - infrared: stars arXiv:astro-ph/0207466v1 22 Jul 2002 A&A manuscript no. ASTRONOMY (will be inserted by hand later) AND Your thesaurus codes are: missing; you have not inserted them ASTROPHYSICS A 2.4 - 12 µm spectrophotometric study with ISO of CygnusX-3 in quiescence ⋆ Lydie Koch-Miramond1, P´eter Abrah´am´ 2,3, Ya¨el Fuchs1,4, Jean-Marc Bonnet-Bidaud1, and Arnaud Claret1 1 DAPNIA/Service d’Astrophysique, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France 2 Konkoly Observatory, P.O. -
Annual Report 2008
Koninklijke Sterrenwacht van België Observatoire royal de Belgique Royal Observatory of Belgium Mensen voor Aarde en Ruimte , Aarde en Ruimte voor Mensen Des hommes et des femmes pour la Terre et l'Espace, La Terre et l'Espace pour l'Homme Jaarverslag 2008 Rapport Annuel 2008 Annual Report 2008 De activiteiten beschreven in dit verslag werden ondersteund door Les activités décrites dans ce rapport ont été soutenues par The activities described in this report were supported by De POD Wetenschapsbeleid / Le SPP Politique Scientifique De Nationale Loterij La Loterie Nationale De Europese Gemeenschap Het Europees Ruimtevaartagentschap La Communauté Européenne L’Agence Spatiale Européenne Het Fond voor Wetenschappelijk Onderzoek Le Fonds de la Recherche Scientifique – Vlaanderen Le Fonds pour la formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA) Instituut voor de aanmoediging van innovatie door Wetenschap & Technologie in Vlaanderen Privé-sponsoring door Mr. G. Berthault / Sponsoring privé par M. G. Berthault 2 Deel 1: Wetenschappelijke activiteiten Partie 1: Activités Scientifiques Part 1: Scientific Activities 3 4 Summary Abbreviations.................................................................................................................................. 7 A. GNSS Positioning and Time............................................................................................. 14 A.1. Time and Time transfer .............................................................................................................15 -
A Basic Requirement for Studying the Heavens Is Determining Where In
Abasic requirement for studying the heavens is determining where in the sky things are. To specify sky positions, astronomers have developed several coordinate systems. Each uses a coordinate grid projected on to the celestial sphere, in analogy to the geographic coordinate system used on the surface of the Earth. The coordinate systems differ only in their choice of the fundamental plane, which divides the sky into two equal hemispheres along a great circle (the fundamental plane of the geographic system is the Earth's equator) . Each coordinate system is named for its choice of fundamental plane. The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the one most closely related to the geographic coordinate system, because they use the same fun damental plane and the same poles. The projection of the Earth's equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles on to the celest ial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate systems: the geographic system is fixed to the Earth; it rotates as the Earth does . The equatorial system is fixed to the stars, so it appears to rotate across the sky with the stars, but of course it's really the Earth rotating under the fixed sky. The latitudinal (latitude-like) angle of the equatorial system is called declination (Dec for short) . It measures the angle of an object above or below the celestial equator. The longitud inal angle is called the right ascension (RA for short). -
Astronomy 2008 Index
Astronomy Magazine Article Title Index 10 rising stars of astronomy, 8:60–8:63 1.5 million galaxies revealed, 3:41–3:43 185 million years before the dinosaurs’ demise, did an asteroid nearly end life on Earth?, 4:34–4:39 A Aligned aurorae, 8:27 All about the Veil Nebula, 6:56–6:61 Amateur astronomy’s greatest generation, 8:68–8:71 Amateurs see fireballs from U.S. satellite kill, 7:24 Another Earth, 6:13 Another super-Earth discovered, 9:21 Antares gang, The, 7:18 Antimatter traced, 5:23 Are big-planet systems uncommon?, 10:23 Are super-sized Earths the new frontier?, 11:26–11:31 Are these space rocks from Mercury?, 11:32–11:37 Are we done yet?, 4:14 Are we looking for life in the right places?, 7:28–7:33 Ask the aliens, 3:12 Asteroid sleuths find the dino killer, 1:20 Astro-humiliation, 10:14 Astroimaging over ancient Greece, 12:64–12:69 Astronaut rescue rocket revs up, 11:22 Astronomers spy a giant particle accelerator in the sky, 5:21 Astronomers unearth a star’s death secrets, 10:18 Astronomers witness alien star flip-out, 6:27 Astronomy magazine’s first 35 years, 8:supplement Astronomy’s guide to Go-to telescopes, 10:supplement Auroral storm trigger confirmed, 11:18 B Backstage at Astronomy, 8:76–8:82 Basking in the Sun, 5:16 Biggest planet’s 5 deepest mysteries, The, 1:38–1:43 Binary pulsar test affirms relativity, 10:21 Binocular Telescope snaps first image, 6:21 Black hole sets a record, 2:20 Black holes wind up galaxy arms, 9:19 Brightest starburst galaxy discovered, 12:23 C Calling all space probes, 10:64–10:65 Calling on Cassiopeia, 11:76 Canada to launch new asteroid hunter, 11:19 Canada’s handy robot, 1:24 Cannibal next door, The, 3:38 Capture images of our local star, 4:66–4:67 Cassini confirms Titan lakes, 12:27 Cassini scopes Saturn’s two-toned moon, 1:25 Cassini “tastes” Enceladus’ plumes, 7:26 Cepheus’ fall delights, 10:85 Choose the dome that’s right for you, 5:70–5:71 Clearing the air about seeing vs. -
ŞAR Shao SPECIAL ISSUE 2013 CİLD 8 № 2 AZERBAIJANI ASTRONOMICAL JOURNAL
ISSN: 2078-4163 XÜSUSİ BURAXILIŞ ŞAR ShAO SPECIAL ISSUE 2013 CİLD 8 № 2 AZERBAIJANI ASTRONOMICAL JOURNAL ISSN: 2078-4163 Azәrbaycan Milli Elmlәr Akademiyası AZӘRBAYCAN ASTRONOMİYA JURNALI Cild 8 – № 2 – 2013 | XÜSUSİ BURAXILIŞ ŞAR - ShAO - ШАО - 60 Azerbaijan National Academy of Sciences Национальная Академия Наук Азербайджана AZERBAIJANI АСТРОНОМИЧЕСКИЙ ASTRONOMICAL ЖУРНАЛ JOURNAL АЗЕРБАЙДЖАНА Volume 8 – No 2 – 2013 Том 8 – № 2 – 2013 SPECIAL ISSUE СПЕЦИАЛЬНЫЙ ВЫПУСК Azәrbaycan Milli Elmlәr Akademiyasının “AZӘRBAYCAN ASTRONOMIYA JURNALI” Azәrbaycan Milli Elmlәr Akademiyası (AMEA) Rәyasәt Heyәtinin 28 aprel 2006-cı il tarixli 50-saylı Sәrәncamı ilә tәsis edilmişdir. Baş Redaktor: Ә.S. Quliyev Baş Redaktorun Müavini: E.S. Babayev Mәsul Katib: P.N. Şustarev REDAKSIYA HEYӘTİ: Cәlilov N.S. AMEA N.Tusi adına Şamaxı Astrofizika Rәsәdxanası Hüseynov R.Ә. Baki Dövlәt Universiteti İsmayılov N.Z. AMEA N.Tusi adına Şamaxı Astrofizika Rәsәdxanası Qasımov F. Q. AMEA Fizika İnsitutu Quluzadә C.M. Baki Dövlәt Universiteti Texniki redaktor: A.B. Әsgәrov İnternet sәhifәsi: http://www.shao.az/AAJ Ünvan: Azәrbaycan, Bakı, AZ-1001, İstiqlaliyyәt küç. 10, AMEA Rәyasәt Heyәti Jurnal AMEA N.Tusi adına Şamaxı Astrofizika Rәsәdxanasında (www.shao.az) nәşr olunur. Мәktublar üçün: ŞAR, Azәrbaycan, Bakı, AZ-1000, Mәrkәzi Poçtamt, a/q №153 e-mail: [email protected] tel.: (+99412) 439 82 48 faкs: (+99412) 497 52 68 2013 Azәrbaycan Milli Elmlәr Akademiyası. 2013 AMEA N.Tusi adına Şamaxı Astrofizika Rәsәdxanası. Bütün hüquqlar qorunmuşdur. Bakı – 2013 ____________________________________________________________________________________________________________ “Астрономический Журнал Азербайджана” Национальной Azerbaijani Astronomical Journal of the Azerbaijan National Академии Наук Азербайджана (НАНА). Academy of Sciences (ANAS) is founded in 28 Aprel 2006. Основан 28 апреля 2006 г. Web- адрес: http://www.shao.az/AAJ Online version: http://www.shao.az/AAJ Главный редактор: А.С.Гулиев Editor-in-Chief: A.S. -
Statistical Properties of a Sample of Periodically Variable B-Type
Astronomy & Astrophysics manuscript no. Lefever © ESO 2018 August 21, 2018 Statistical properties of a sample of periodically variable B-type supergiants ⋆ Evidence for opacity-driven gravity-mode oscillations K. Lefever1, J. Puls2, and C. Aerts1,3 1 Instituut voor Sterrenkunde, K.U.Leuven, Celestijnenlaan 200B, B–3001 Leuven, Belgium 2 Universit¨atssternwarte M¨unchen, Scheinerstr. 1, D-81679 M¨unchen, Germany 3 Departement Astrofysica, Radboud Universiteit van Nijmegen, PO Box 9010, 6500 GL Nijmegen, the Netherlands Received 14 July 2006 / Accepted 3 November 2006 ABSTRACT Aims. We have studied a sample of 28 periodically variable B-type supergiants selected from the HIPPARCOS mission and 12 comparison stars covering the whole B-type spectral range. Our goal is to test if their variability is compatible with opacity-driven non-radial oscillations. Methods. We have used the NLTE atmosphere code FASTWIND to derive the atmospheric and wind parameters of the complete sample through line profile fitting. We applied the method to selected H, He and Si line profiles, measured with the high resolution CES spectrograph attached to the ESO CAT telescope in La Silla, Chile. Results. From the location of the stars in the (log Teff , log g) diagram, we suggest that variability of our sample supergiants is indeed due to the gravity modes resulting from the opacity mechanism. We find nine of the comparison stars to be periodically variable as well, and suggest them to be new α Cyg variables. We find marginal evidence of a correlation between the amplitude of the photometric variability and the wind density. We investigate the Wind Momentum Luminosity Relation for the whole range of B spectral type supergiants, and find that the later types (> B5) perfectly follow the relation for A supergiants. -
CURRICULUM VITAE: Dr Richard Ignace
CURRICULUM VITAE: Dr Richard Ignace Address: Department of Physics & Astronomy Office of Undergraduate Research College of Arts & Sciences Honors College EAST TENNESSEE STATE UNIVERSITY EAST TENNESSEE STATE UNIVERSITY Johnson City, TN 37614 Johnson City, TN 37614 Email: [email protected] [email protected] Web: faculty.etsu.edu/ignace www.etsu.edu/honors/ug research Phone/Fax: (423) 439-6904 / (423) 439-6905 (423) 439-6073 / (423) 439-6080 EDUCATION Ph.D. in Astronomy, University of Wisconsin 1996 M.S. in Physics, University of Wisconsin 1994 M.S. in Astronomy, University of Wisconsin 1993 B.S. in Astronomy, Indiana University 1991 POSITIONS HELD Aug 2016–present, Consultant, Tri-Alpha Energy Jan 2015–present, Director of Undergraduate Research Activities, East Tennessee State University Aug 2013–present, Full Professor: East Tennessee State University Aug 2007–Jul 2013, Associate Professor: East Tennessee State University Aug 2003–Jul 2007, Assistant Professor: East Tennessee State University Sep 2002–Jul 2003, Assistant Scientist: University of Wisconsin Aug 1999–Aug 2002, Visiting Assistant Professor: University of Iowa Nov 1996–Aug 1999, Postdoctoral Research Assistant: University of Glasgow SELECTED PROFESSIONAL ACTIVITIES Involved with service to discipline, institution, and community As Director of Undergraduate Research & Creative Activities, I administrate grant programs and activ- ities that support undergraduate scholarship, plus advocate for undergraduate research. Successful with publishing scholarly articles and competing for grant funding; author of the astron- omy textbook “Astro4U: An Introduction to the Science of the Cosmos,” of the popular astronomy book “Understanding the Universe,” and co-editor of the conference proceedings “The Nature and Evolution of Disks around Hot Stars” Principal organizer for STELLAR POLARIMETRY: FROM BIRTH TO DEATH, Jun 2011; and THE NATURE AND EVOLUTION OF DISKS AROUND HOT STARS, Jul 2004. -
Arxiv:0908.2624V1 [Astro-Ph.SR] 18 Aug 2009
Astronomy & Astrophysics Review manuscript No. (will be inserted by the editor) Accurate masses and radii of normal stars: Modern results and applications G. Torres · J. Andersen · A. Gim´enez Received: date / Accepted: date Abstract This paper presents and discusses a critical compilation of accurate, fun- damental determinations of stellar masses and radii. We have identified 95 detached binary systems containing 190 stars (94 eclipsing systems, and α Centauri) that satisfy our criterion that the mass and radius of both stars be known to ±3% or better. All are non-interacting systems, so the stars should have evolved as if they were single. This sample more than doubles that of the earlier similar review by Andersen (1991), extends the mass range at both ends and, for the first time, includes an extragalactic binary. In every case, we have examined the original data and recomputed the stellar parameters with a consistent set of assumptions and physical constants. To these we add interstellar reddening, effective temperature, metal abundance, rotational velocity and apsidal motion determinations when available, and we compute a number of other physical parameters, notably luminosity and distance. These accurate physical parameters reveal the effects of stellar evolution with un- precedented clarity, and we discuss the use of the data in observational tests of stellar evolution models in some detail. Earlier findings of significant structural differences between moderately fast-rotating, mildly active stars and single stars, ascribed to the presence of strong magnetic and spot activity, are confirmed beyond doubt. We also show how the best data can be used to test prescriptions for the subtle interplay be- tween convection, diffusion, and other non-classical effects in stellar models. -
Absence of Hot Gas Within the Wolft-Rayet Bubble Around WR16
Astronomy & Astrophysics manuscript no. ms c ESO 2018 April 30, 2018 Absence of hot gas within the Wolf-Rayet bubble around WR 16 J.A. Toal´aand M.A. Guerrero Instituto de Astrof´ısica de Andaluc´ıa, IAA-CSIC, Glorieta de la Astronom´ıa s/n, 18008 Granada, Spain; [email protected] Preprint online version: April 30, 2018 ABSTRACT We present the analysis of XMM-Newton archival observations towards the Wolf-Rayet (WR) bubble around WR 16. Despite the closed bubble morphology of this WR nebula, the XMM-Newton observations show no evidence of diffuse emission in its interior as in the similar WR bubbles NGC 6888 and S 308. We use the present observations to estimate a 3-σ upper limit to the X-ray luminosity in the 0.3–1.5 keV energy band equal to 7.4×1032 erg s−1 for the diffuse emission from the WR nebula, assuming a distance of 2.37 kpc. The WR nebula around WR 16 is the fourth observed by the current generation of X-ray satellites and the second not detected. We also examine FUSE spectra to search for nebular O vi absorption lines in the stellar continuum of WR 16. The present far-UV data and the lack of measurements of the dynamics of the optical WR bubble do not allow us to confirm the existence of a conductive layer of gas at T∼3×105 K between the cold nebular gas and the hot gas in its interior. The present observations result in an upper limit of −3 ne <0.6 cm on the electron density of the X-ray emitting material within the nebula.