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Stellar Variability in Open Clusters. I. a New Class of Variable Stars in NGC
Astronomy & Astrophysics manuscript no. ngc3766˙v3˙1b c ESO 2018 September 8, 2018 Stellar variability in open clusters I. A new class of variable stars in NGC 3766 N. Mowlavi1, F. Barblan1, S. Saesen1, and L. Eyer1 1Astronomy Department, Geneva Observatory, chemin des Maillettes, 1290 Versoix, Switzerland e-mail: [email protected] Accepted 16/04/2013 ABSTRACT Aims. We analyze the population of periodic variable stars in the open cluster NGC 3766 based on a 7-year multiband monitoring campaign conducted on the 1.2 m Swiss Euler telescope at La Silla, Chili. Methods. The data reduction, light curve cleaning, and period search procedures, combined with the long observation time line, allowed us to detect variability amplitudes down to the mmag level. The variability properties were complemented with the positions in the color-magnitude and color-color diagrams to classify periodic variable stars into distinct variability types. Results. We find a large population (36 stars) of new variable stars between the red edge of slowly pulsating B (SPB) stars and the blue edge of δ Sct stars, a region in the Hertzsprung-Russell (HR) diagram where no pulsation is predicted to occur based on standard stellar models. The bulk of their periods ranges from 0.1 to 0.7 d, with amplitudes between 1 and 4 mmag for the majority of them. About 20% of stars in that region of the HR diagram are found to be variable, but the number of members of this new group is expected to be higher, with amplitudes below our mmag detection limit. -
Abstracts Connecting to the Boston University Network
20th Cambridge Workshop: Cool Stars, Stellar Systems, and the Sun July 29 - Aug 3, 2018 Boston / Cambridge, USA Abstracts Connecting to the Boston University Network 1. Select network ”BU Guest (unencrypted)” 2. Once connected, open a web browser and try to navigate to a website. You should be redirected to https://safeconnect.bu.edu:9443 for registration. If the page does not automatically redirect, go to bu.edu to be brought to the login page. 3. Enter the login information: Guest Username: CoolStars20 Password: CoolStars20 Click to accept the conditions then log in. ii Foreword Our story starts on January 31, 1980 when a small group of about 50 astronomers came to- gether, organized by Andrea Dupree, to discuss the results from the new high-energy satel- lites IUE and Einstein. Called “Cool Stars, Stellar Systems, and the Sun,” the meeting empha- sized the solar stellar connection and focused discussion on “several topics … in which the similarity is manifest: the structures of chromospheres and coronae, stellar activity, and the phenomena of mass loss,” according to the preface of the resulting, “Special Report of the Smithsonian Astrophysical Observatory.” We could easily have chosen the same topics for this meeting. Over the summer of 1980, the group met again in Bonas, France and then back in Cambridge in 1981. Nearly 40 years on, I am comfortable saying these workshops have evolved to be the premier conference series for cool star research. Cool Stars has been held largely biennially, alternating between North America and Europe. Over that time, the field of stellar astro- physics has been upended several times, first by results from Hubble, then ROSAT, then Keck and other large aperture ground-based adaptive optics telescopes. -
Open Clusters in Gaia
Sede Amministrativa: Università degli Studi di Padova Dipartimento di Fisica e Astronomia “G. Galilei” Corso di Dottorato di Ricerca in Astronomia Ciclo XXX OPEN CLUSTERS IN GAIA ERA Coordinatore: Ch.mo Prof. Giampaolo Piotto Supervisore: Dr.ssa Antonella Vallenari Dottorando: Francesco Pensabene i Abstract Context. Open clusters (OCs) are optimal tracers of the Milky Way disc. They are observed at every distance from the Galactic center and their ages cover the entire lifespan of the disc. The actual OC census contain more than 3000 objects, but suffers of incom- pleteness out of the solar neighborhood and of large inhomogeneity in the parameter deter- minations present in literature. Both these aspects will be improved by the on-going space mission Gaia . In the next years Gaia will produce the most precise three-dimensional map of the Milky Way by surveying other than 1 billion of stars. For those stars Gaia will provide extremely precise measure- ment of proper motions, parallaxes and brightness. Aims. In this framework we plan to take advantage of the first Gaia data release, while preparing for the coming ones, to: i) move the first steps towards building a homogeneous data base of OCs with the high quality Gaia astrometry and photometry; ii) build, improve and test tools for the analysis of large sample of OCs; iii) use the OCs to explore the prop- erties of the disc in the solar neighborhood. Methods and Data. Using ESO archive data, we analyze the photometry and derive physical parameters, comparing data with synthetic populations and luminosity functions, of three clusters namely NGC 2225, NGC 6134 and NGC 2243. -
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). -
The List of Possible Double and Multiple Open Clusters Between Galactic Longitudes 240O and 270O
The list of possible double and multiple open clusters between galactic longitudes 240o and 270o Juan Casado Facultad de Ciencias, Universidad Autónoma de Barcelona, 08193, Bellaterra, Catalonia, Spain Email: [email protected] Abstract This work studies the candidate double and multiple open clusters (OCs) in the galactic sector from l = 240o to l = 270o, which contains the Vela-Puppis star formation region. To do that, we have searched the most recent and complete catalogues of OCs by hand to get an extensive list of 22 groups of OCs involving 80 candidate members. Gaia EDR3 has been used to review some of the candidate OCs and look for new OCs near the candidate groups. Gaia data also permitted filtering out most of the field sources that are not member stars of the OCs. The plotting of combined colour-magnitude diagrams of candidate pairs has allowed, in several cases, endorsing or discarding their link. The most likely systems are formed by OCs less than 0.1 Gyr old, with only one eccentric OC in this respect. No probable system of older OCs has been found. Preliminary estimations of the fraction of known OCs that form part of groups (9.4 to 15%) support the hypothesis that the Galaxy and the Large Magellanic Cloud are similar in this respect. The results indicate that OCs are born in groups like stars are born in OCs. Keywords Binary open clusters; Open cluster groups; Open cluster formation; Gaia; Manual search; Large Magellanic Cloud. 1. Introduction Open clusters are formed in giant molecular clouds and there is observational evidence suggesting that they can form in groups (Camargo et al. -
LIST of PUBLICATIONS Aryabhatta Research Institute of Observational Sciences ARIES (An Autonomous Scientific Research Institute
LIST OF PUBLICATIONS Aryabhatta Research Institute of Observational Sciences ARIES (An Autonomous Scientific Research Institute of Department of Science and Technology, Govt. of India) Manora Peak, Naini Tal - 263 129, India (1955−2020) ABBREVIATIONS AA: Astronomy and Astrophysics AASS: Astronomy and Astrophysics Supplement Series ACTA: Acta Astronomica AJ: Astronomical Journal ANG: Annals de Geophysique Ap. J.: Astrophysical Journal ASP: Astronomical Society of Pacific ASR: Advances in Space Research ASS: Astrophysics and Space Science AE: Atmospheric Environment ASL: Atmospheric Science Letters BA: Baltic Astronomy BAC: Bulletin Astronomical Institute of Czechoslovakia BASI: Bulletin of the Astronomical Society of India BIVS: Bulletin of the Indian Vacuum Society BNIS: Bulletin of National Institute of Sciences CJAA: Chinese Journal of Astronomy and Astrophysics CS: Current Science EPS: Earth Planets Space GRL : Geophysical Research Letters IAU: International Astronomical Union IBVS: Information Bulletin on Variable Stars IJHS: Indian Journal of History of Science IJPAP: Indian Journal of Pure and Applied Physics IJRSP: Indian Journal of Radio and Space Physics INSA: Indian National Science Academy JAA: Journal of Astrophysics and Astronomy JAMC: Journal of Applied Meterology and Climatology JATP: Journal of Atmospheric and Terrestrial Physics JBAA: Journal of British Astronomical Association JCAP: Journal of Cosmology and Astroparticle Physics JESS : Jr. of Earth System Science JGR : Journal of Geophysical Research JIGR: Journal of Indian -
The SAI Catalog of Supernovae and Radial Distributions of Supernovae
Astronomy Letters, Vol. 30, No. 11, 2004, pp. 729–736. Translated from Pis’ma v Astronomicheski˘ı Zhurnal, Vol. 30, No. 11, 2004, pp. 803–811. Original Russian Text Copyright c 2004 by Tsvetkov, Pavlyuk, Bartunov. TheSAICatalogofSupernovaeandRadialDistributions of Supernovae of Various Types in Galaxies D. Yu. Tsvetkov*, N.N.Pavlyuk**,andO.S.Bartunov*** Sternberg Astronomical Institute, Universitetski ˘ı pr. 13, Moscow, 119992 Russia Received May 18, 2004 Abstract—We describe the Sternberg Astronomical Institute (SAI)catalog of supernovae. We show that the radial distributions of type-Ia, type-Ibc, and type-II supernovae differ in the central parts of spiral galaxies and are similar in their outer regions, while the radial distribution of type-Ia supernovae in elliptical galaxies differs from that in spiral and lenticular galaxies. We give a list of the supernovae that are farthest from the galactic centers, estimate their relative explosion rate, and discuss their possible origins. c 2004MAIK “Nauka/Interperiodica”. Key words: astronomical catalogs, supernovae, observations, radial distributions of supernovae. INTRODUCTION be found on the Internet. The most complete data are contained in the list of SNe maintained by the Cen- In recent years, interest in studying supernovae (SNe)has increased signi ficantly. Among other rea- tral Bureau of Astronomical Telegrams (http://cfa- sons, this is because SNe Ia are used as “standard www.harvard.edu/cfa/ps/lists/Supernovae.html)and candles” for constructing distance scales and for cos- the electronic version of the Asiago catalog mological studies, and because SNe Ibc may be re- (http://web.pd.astro.it/supern). lated to gamma ray bursts. -
407 a Abell Galaxy Cluster S 373 (AGC S 373) , 351–353 Achromat
Index A Barnard 72 , 210–211 Abell Galaxy Cluster S 373 (AGC S 373) , Barnard, E.E. , 5, 389 351–353 Barnard’s loop , 5–8 Achromat , 365 Barred-ring spiral galaxy , 235 Adaptive optics (AO) , 377, 378 Barred spiral galaxy , 146, 263, 295, 345, 354 AGC S 373. See Abell Galaxy Cluster Bean Nebulae , 303–305 S 373 (AGC S 373) Bernes 145 , 132, 138, 139 Alnitak , 11 Bernes 157 , 224–226 Alpha Centauri , 129, 151 Beta Centauri , 134, 156 Angular diameter , 364 Beta Chamaeleontis , 269, 275 Antares , 129, 169, 195, 230 Beta Crucis , 137 Anteater Nebula , 184, 222–226 Beta Orionis , 18 Antennae galaxies , 114–115 Bias frames , 393, 398 Antlia , 104, 108, 116 Binning , 391, 392, 398, 404 Apochromat , 365 Black Arrow Cluster , 73, 93, 94 Apus , 240, 248 Blue Straggler Cluster , 169, 170 Aquarius , 339, 342 Bok, B. , 151 Ara , 163, 169, 181, 230 Bok Globules , 98, 216, 269 Arcminutes (arcmins) , 288, 383, 384 Box Nebula , 132, 147, 149 Arcseconds (arcsecs) , 364, 370, 371, 397 Bug Nebula , 184, 190, 192 Arditti, D. , 382 Butterfl y Cluster , 184, 204–205 Arp 245 , 105–106 Bypass (VSNR) , 34, 38, 42–44 AstroArt , 396, 406 Autoguider , 370, 371, 376, 377, 388, 389, 396 Autoguiding , 370, 376–378, 380, 388, 389 C Caldwell Catalogue , 241 Calibration frames , 392–394, 396, B 398–399 B 257 , 198 Camera cool down , 386–387 Barnard 33 , 11–14 Campbell, C.T. , 151 Barnard 47 , 195–197 Canes Venatici , 357 Barnard 51 , 195–197 Canis Major , 4, 17, 21 S. Chadwick and I. Cooper, Imaging the Southern Sky: An Amateur Astronomer’s Guide, 407 Patrick Moore’s Practical -
Atlas Menor Was Objects to Slowly Change Over Time
C h a r t Atlas Charts s O b by j Objects e c t Constellation s Objects by Number 64 Objects by Type 71 Objects by Name 76 Messier Objects 78 Caldwell Objects 81 Orion & Stars by Name 84 Lepus, circa , Brightest Stars 86 1720 , Closest Stars 87 Mythology 88 Bimonthly Sky Charts 92 Meteor Showers 105 Sun, Moon and Planets 106 Observing Considerations 113 Expanded Glossary 115 Th e 88 Constellations, plus 126 Chart Reference BACK PAGE Introduction he night sky was charted by western civilization a few thou - N 1,370 deep sky objects and 360 double stars (two stars—one sands years ago to bring order to the random splatter of stars, often orbits the other) plotted with observing information for T and in the hopes, as a piece of the puzzle, to help “understand” every object. the forces of nature. The stars and their constellations were imbued with N Inclusion of many “famous” celestial objects, even though the beliefs of those times, which have become mythology. they are beyond the reach of a 6 to 8-inch diameter telescope. The oldest known celestial atlas is in the book, Almagest , by N Expanded glossary to define and/or explain terms and Claudius Ptolemy, a Greco-Egyptian with Roman citizenship who lived concepts. in Alexandria from 90 to 160 AD. The Almagest is the earliest surviving astronomical treatise—a 600-page tome. The star charts are in tabular N Black stars on a white background, a preferred format for star form, by constellation, and the locations of the stars are described by charts. -
Centaurus Kentaur
Lateinischer Name: Deutscher Name: Cen Centaurus Kentaur Atlas Karte (2000.0) Kulmination um Cambridge 17 Mitternacht: Star Atlas 20, 21, Sky Atlas Cen_chart.gif Cen_chart.gif 25 6. April Deklinationsbereich: -64° ... -30° Fläche am Himmel: 1060° 2 Benachbarte Sternbilder: Ant Car Cir Cru Hya Lib Lup Mus Vel Mythologie und Geschichte: Die Zentauren waren in der griechischen Mythologie meist wilde Mischwesen mit dem Oberkörper eines Menschen bis zur Hüfte, darunter dem Leib eines Pferdes. Der Zentaur Chiron aber war dagegen sehr weise und besonders in der Medizin, Musik und Botanik bewandert. Er war der Lehrer des Achill und des Asklepios. Chiron war auch der Beschützer vieler Helden und hat angeblich die Sternbilder "erfunden". Selbst an den Himmel versetzt wurde er, nachdem ihn Herkules aus Versehen mit einem vergifteten Pfeil getroffen hatte (diese Erklärung wird manchmal auch für Sagittarius überliefert, einen anderen "himmlischen" Zentauren). Am Himmel soll er den in einen Wolf verwandelten König Lykaon (Lupus ) in Schach halten. Das Sternbild war den Griechen bekannt, da es infolge der Präzession der Erdachse vor 2000-3000 Jahren vom Mittelmeerraum, Unterägypten und Vorderasien aus voll gesehen werden konnte. [bk7 ] Sternbild: Centaurus ist ein ausgedehntes Sternbild mit ungewöhnlich vielen hellen Sternen und einer Fläche von 1060 Quadratgrad, südlich von Hydra . Das Zentrum kulminiert jeweils etwa am 6. April um Mitternacht. Zwischen den Hufen des Zentauren befindet sich das Kreuz des Südens . [bk9 , bk15 ] Interessante Objekte: -