Many New Variable Stars Discovered in the Core of the Globular Cluster NGC 6715 (M 54) with EMCCD Observations DOI: 10.1051/0004-6361/201628864
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Midwife of the Galactic Zoo
FOCUS 30 A miniature milky way: approximately 40 million light-years away, UGC 5340 is classified as a dwarf galaxy. Dwarf galaxies exist in a variety of forms – elliptical, spheroidal, spiral, or irregular – and originate in small halos of dark matter. Dwarf galaxies contain the oldest known stars. Max Planck Research · 4 | 2020 FOCUS MIDWIFE OF THE GALACTIC ZOO TEXT: THOMAS BÜHRKE 31 IMAGE: NASA, TEAM ESA & LEGUS Stars cluster in galaxies of dramatically different shapes and sizes: elliptical galaxies, spheroidal galaxies, lenticular galaxies, spiral galaxies, and occasionally even irregular galaxies. Nadine Neumayer at the Max Planck Institute for Astronomy in Heidelberg and Ralf Bender at the Max Planck Institute for Extraterrestrial Physics in Garching investigate the reasons for this diversity. They have already identified one crucial factor: dark matter. Max Planck Research · 4 | 2020 FOCUS Nature has bestowed an overwhelming diversity upon our planet. The sheer resourcefulness of the plant and animal world is seemingly inexhaustible. When scien- tists first started to explore this diversity, their first step was always to systematize it. Hence, the Swedish naturalist Carl von Linné established the principles of modern botany and zoology in the 18th century by clas- sifying organisms. In the last century, astronomers have likewise discovered that galaxies can come in an array of shapes and sizes. In this case, it was Edwin Hubble in the mid-1920s who systematized them. The “Hubble tuning fork dia- gram” classified elliptical galaxies according to their ellipticity. The series of elliptical galaxies along the di- PHOTO: PETER FRIEDRICH agram branches off into two arms: spiral galaxies with a compact bulge along the upper branch and galaxies with a central bar on the lower branch. -
Spatial Distribution of Galactic Globular Clusters: Distance Uncertainties and Dynamical Effects
Juliana Crestani Ribeiro de Souza Spatial Distribution of Galactic Globular Clusters: Distance Uncertainties and Dynamical Effects Porto Alegre 2017 Juliana Crestani Ribeiro de Souza Spatial Distribution of Galactic Globular Clusters: Distance Uncertainties and Dynamical Effects Dissertação elaborada sob orientação do Prof. Dr. Eduardo Luis Damiani Bica, co- orientação do Prof. Dr. Charles José Bon- ato e apresentada ao Instituto de Física da Universidade Federal do Rio Grande do Sul em preenchimento do requisito par- cial para obtenção do título de Mestre em Física. Porto Alegre 2017 Acknowledgements To my parents, who supported me and made this possible, in a time and place where being in a university was just a distant dream. To my dearest friends Elisabeth, Robert, Augusto, and Natália - who so many times helped me go from "I give up" to "I’ll try once more". To my cats Kira, Fen, and Demi - who lazily join me in bed at the end of the day, and make everything worthwhile. "But, first of all, it will be necessary to explain what is our idea of a cluster of stars, and by what means we have obtained it. For an instance, I shall take the phenomenon which presents itself in many clusters: It is that of a number of lucid spots, of equal lustre, scattered over a circular space, in such a manner as to appear gradually more compressed towards the middle; and which compression, in the clusters to which I allude, is generally carried so far, as, by imperceptible degrees, to end in a luminous center, of a resolvable blaze of light." William Herschel, 1789 Abstract We provide a sample of 170 Galactic Globular Clusters (GCs) and analyse its spatial distribution properties. -
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). -
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. -
Gaia Data Release 2 Special Issue
A&A 623, A110 (2019) Astronomy https://doi.org/10.1051/0004-6361/201833304 & © ESO 2019 Astrophysics Gaia Data Release 2 Special issue Gaia Data Release 2 Variable stars in the colour-absolute magnitude diagram?,?? Gaia Collaboration, L. Eyer1, L. Rimoldini2, M. Audard1, R. I. Anderson3,1, K. Nienartowicz2, F. Glass1, O. Marchal4, M. Grenon1, N. Mowlavi1, B. Holl1, G. Clementini5, C. Aerts6,7, T. Mazeh8, D. W. Evans9, L. Szabados10, A. G. A. Brown11, A. Vallenari12, T. Prusti13, J. H. J. de Bruijne13, C. Babusiaux4,14, C. A. L. Bailer-Jones15, M. Biermann16, F. Jansen17, C. Jordi18, S. A. Klioner19, U. Lammers20, L. Lindegren21, X. Luri18, F. Mignard22, C. Panem23, D. Pourbaix24,25, S. Randich26, P. Sartoretti4, H. I. Siddiqui27, C. Soubiran28, F. van Leeuwen9, N. A. Walton9, F. Arenou4, U. Bastian16, M. Cropper29, R. Drimmel30, D. Katz4, M. G. Lattanzi30, J. Bakker20, C. Cacciari5, J. Castañeda18, L. Chaoul23, N. Cheek31, F. De Angeli9, C. Fabricius18, R. Guerra20, E. Masana18, R. Messineo32, P. Panuzzo4, J. Portell18, M. Riello9, G. M. Seabroke29, P. Tanga22, F. Thévenin22, G. Gracia-Abril33,16, G. Comoretto27, M. Garcia-Reinaldos20, D. Teyssier27, M. Altmann16,34, R. Andrae15, I. Bellas-Velidis35, K. Benson29, J. Berthier36, R. Blomme37, P. Burgess9, G. Busso9, B. Carry22,36, A. Cellino30, M. Clotet18, O. Creevey22, M. Davidson38, J. De Ridder6, L. Delchambre39, A. Dell’Oro26, C. Ducourant28, J. Fernández-Hernández40, M. Fouesneau15, Y. Frémat37, L. Galluccio22, M. García-Torres41, J. González-Núñez31,42, J. J. González-Vidal18, E. Gosset39,25, L. P. Guy2,43, J.-L. Halbwachs44, N. C. Hambly38, D. -
Stars and Their Spectra: an Introduction to the Spectral Sequence Second Edition James B
Cambridge University Press 978-0-521-89954-3 - Stars and Their Spectra: An Introduction to the Spectral Sequence Second Edition James B. Kaler Index More information Star index Stars are arranged by the Latin genitive of their constellation of residence, with other star names interspersed alphabetically. Within a constellation, Bayer Greek letters are given first, followed by Roman letters, Flamsteed numbers, variable stars arranged in traditional order (see Section 1.11), and then other names that take on genitive form. Stellar spectra are indicated by an asterisk. The best-known proper names have priority over their Greek-letter names. Spectra of the Sun and of nebulae are included as well. Abell 21 nucleus, see a Aurigae, see Capella Abell 78 nucleus, 327* ε Aurigae, 178, 186 Achernar, 9, 243, 264, 274 z Aurigae, 177, 186 Acrux, see Alpha Crucis Z Aurigae, 186, 269* Adhara, see Epsilon Canis Majoris AB Aurigae, 255 Albireo, 26 Alcor, 26, 177, 241, 243, 272* Barnard’s Star, 129–130, 131 Aldebaran, 9, 27, 80*, 163, 165 Betelgeuse, 2, 9, 16, 18, 20, 73, 74*, 79, Algol, 20, 26, 176–177, 271*, 333, 366 80*, 88, 104–105, 106*, 110*, 113, Altair, 9, 236, 241, 250 115, 118, 122, 187, 216, 264 a Andromedae, 273, 273* image of, 114 b Andromedae, 164 BDþ284211, 285* g Andromedae, 26 Bl 253* u Andromedae A, 218* a Boo¨tis, see Arcturus u Andromedae B, 109* g Boo¨tis, 243 Z Andromedae, 337 Z Boo¨tis, 185 Antares, 10, 73, 104–105, 113, 115, 118, l Boo¨tis, 254, 280, 314 122, 174* s Boo¨tis, 218* 53 Aquarii A, 195 53 Aquarii B, 195 T Camelopardalis, -
The Messier Catalog
The Messier Catalog Messier 1 Messier 2 Messier 3 Messier 4 Messier 5 Crab Nebula globular cluster globular cluster globular cluster globular cluster Messier 6 Messier 7 Messier 8 Messier 9 Messier 10 open cluster open cluster Lagoon Nebula globular cluster globular cluster Butterfly Cluster Ptolemy's Cluster Messier 11 Messier 12 Messier 13 Messier 14 Messier 15 Wild Duck Cluster globular cluster Hercules glob luster globular cluster globular cluster Messier 16 Messier 17 Messier 18 Messier 19 Messier 20 Eagle Nebula The Omega, Swan, open cluster globular cluster Trifid Nebula or Horseshoe Nebula Messier 21 Messier 22 Messier 23 Messier 24 Messier 25 open cluster globular cluster open cluster Milky Way Patch open cluster Messier 26 Messier 27 Messier 28 Messier 29 Messier 30 open cluster Dumbbell Nebula globular cluster open cluster globular cluster Messier 31 Messier 32 Messier 33 Messier 34 Messier 35 Andromeda dwarf Andromeda Galaxy Triangulum Galaxy open cluster open cluster elliptical galaxy Messier 36 Messier 37 Messier 38 Messier 39 Messier 40 open cluster open cluster open cluster open cluster double star Winecke 4 Messier 41 Messier 42/43 Messier 44 Messier 45 Messier 46 open cluster Orion Nebula Praesepe Pleiades open cluster Beehive Cluster Suburu Messier 47 Messier 48 Messier 49 Messier 50 Messier 51 open cluster open cluster elliptical galaxy open cluster Whirlpool Galaxy Messier 52 Messier 53 Messier 54 Messier 55 Messier 56 open cluster globular cluster globular cluster globular cluster globular cluster Messier 57 Messier -
Lowmetallicity Pulsating Stars in the Lamost
LOW-METALLICITY PULSATING STARS IN THE LAMOST DR1 F. Kahraman Aliçavuş Çanakkale Onsekiz Mart University [email protected] Aim Finding new low-metallicity pulsating stars in the LAMOST DR1 and uncovering their pulsation and atmospheric parameters. WHY ? They protect detailed information about the place where they were born. Alow us to understand evolution of the Galaxy, formation of stars Low-metallicity pulsating stars (taken from Jeffery (2008)) Low-metallicity pulsating stars RR Lyare stars: ● Classical radial pulsator, Pulsation period = ~0.5 days ● Exication mechanism, HeII, HeIII ionization zone ● Mass => ~0.6 ± 0.8 Msun ● Horizontal bracnh stars ● Teff => 6100 ± 7400 K (Taken from http://www.physics.usyd.edu.au/~bedding/animations/visual.html) RRab RRd RRc (Smolec et al., 2017, MNRAS, 467, 2349) Low-metallicity pulsating stars Type II Cepheids ● partial ionization zone of He ii ± Heiii and of Hi ± Hii ● Period 1 ± 5 d ==> BL Herculis ● Period 10 ± 20 d ==> W Virginis ● Period > 20 d ==> RV Tauri Taken from Aerts C., Christensen-Dalsgaard J., Kurtz D. W., 2010, Astroseismology, Springer, Berlin Low-metallicity pulsating stars Anomalous Cepheids: ● 1 ± 2 Msun ● spread between classical and type II Cepheids in the period-luminosity diagram (http://ogle.astrouw.edu.pl/atlas/anomalous_Cepheids.html) Low-metallicity pulsating stars SX Phoenix stars: ● Similar to high amplitude d Scuti star, Low- metallicity ● Mass => 0.9 ± 1.5 Msun ● Sx Phe stars are believed to be blue stragglers. ● Amplitude > 0.1 mag, Amplitude >~0.02 ± 0.03 mag Taken from Aerts C., Christensen- Dalsgaard J., Kurtz D. W., 2010, Astroseismology, Springer, Berlin Target Selection ● DR1 AFGK Stars Catalog, R=1800, SNg > 6, l = 370 ± 900 nm ● Teff ==> 6500 ± 8600 K ● log g ==> 3.8 ± 4.5 ● Fe/H ==> -2.4 ± -0.5 dex (http://dr1.lamost.org/) Target Selection ● SuperWASP Data, extra-solar planet detection programme ● Two robotic observatories, eight wide-angle cameras ● 10 objects showing light variation were found. -
Basic Astronomy Labs
Astronomy Laboratory Exercise 31 The Magnitude Scale On a dark, clear night far from city lights, the unaided human eye can see on the order of five thousand stars. Some stars are bright, others are barely visible, and still others fall somewhere in between. A telescope reveals hundreds of thousands of stars that are too dim for the unaided eye to see. Most stars appear white to the unaided eye, whose cells for detecting color require more light. But the telescope reveals that stars come in a wide palette of colors. This lab explores the modern magnitude scale as a means of describing the brightness, the distance, and the color of a star. The earliest recorded brightness scale was developed by Hipparchus, a natural philosopher of the second century BCE. He ranked stars into six magnitudes according to brightness. The brightest stars were first magnitude, the second brightest stars were second magnitude, and so on until the dimmest stars he could see, which were sixth magnitude. Modern measurements show that the difference between first and sixth magnitude represents a brightness ratio of 100. That is, a first magnitude star is about 100 times brighter than a sixth magnitude star. Thus, each magnitude is 100115 (or about 2. 512) times brighter than the next larger, integral magnitude. Hipparchus' scale only allows integral magnitudes and does not allow for stars outside this range. With the invention of the telescope, it became obvious that a scale was needed to describe dimmer stars. Also, the scale should be able to describe brighter objects, such as some planets, the Moon, and the Sun. -
Classification of Population Ii Supergiants and Related Stars in the Vilnius System
Baltic Astronomy, vol.1, 216-238, 1992. CLASSIFICATION OF POPULATION II SUPERGIANTS AND RELATED STARS IN THE VILNIUS SYSTEM A. Bartkevicius, R. Lazauskaite and G. Tautvaisiene Institute of Theoretical Physics and Astronomy, Gostauto 12, Vilnius 2600, Lithuania Received February 26, 1992 . Abstract. The results of photometric classification in the Vilnius system of 117 Population II supergiants, suspected supergiants and related stars are given. Their photometric spectral types, intrinsic colour indices (Y-V)o, colour excesses Ey-v, metallicities [Fe/H] and absolute magnitudes My are determined. It is shown that the system allows us to detect the UU Herculis-type supergiants pho- tometrically. The analyzed SRd star sample falls into two groups of metallicity and luminosity. Our photometric classification assigns luminosity classes from III to V to 37 F-K stars with |6| > 16° clas- sified by Bartaya (1979) from objective prism spectra as supergiants. Key words: supergiant stars - Population II stars - UU Herculis- type stars - photometric classification - Vilnius photometric system 1. Introduction A part of Population II stars evolve into supergiants when they reach the tip of the asymptotic gi;ant branch (AGB) and the post- AGB stage. Space density of such stars, because of their rapid evo- lution, is not as high as for other Population II stars (e.g. subdwarfs, metal-deficient giants, RR Lyrae-ty pe stars, horizontal branch stars). This is also confirmed by the H-R diagrams of globular clusters. How- ever, high luminosity and location sd high galactic latitudes where in- terstellar extinction is low allows us to observe a rather large number Send offprint requests to: A. -
Lefevre Laure 2006 These.Pdf (9.250Mb)
Etude de la variabilité des étoiles massives à l’aide de la photométrie et de la spectroscopie par Laure Lefèvre Thèse de doctorat effectuée en cotutelle au Département de Physique Faculté des arts et des sciences Université de Montréal et à L’Observatoire Astronomique de Strasbourg Université Louis Pasteur, $trasbourg, France Thèse présentée à la faculté des études supérieures de l’Université de Montréal en vue de l’obtention du grade de Philosophiae Doctor (Ph. D.) en physique et à l’Université Louis Pasteur en vue de l’Obtention du grade de Docteur de l’Université Louis Pasteur en astrophysique Février, 2006 © Laure Lefèvre. 2006 ‘\L OCR Université de Monfréal Direction des bibliothèques AVIS L’auteur a autorisé l’Université de Montréal à reproduire et diffuser, en totalité ou en partie, par quelque moyen que ce soit et sur quelque support que ce soit, et exclusivement à des fins non lucratives d’enseignement et de recherche, des copies de ce mémoire ou de cette thèse. L’auteur et les coauteurs le cas échéant conservent la propriété du droit d’auteur et des droits moraux qui protègent ce document. Ni la thèse ou le mémoire, ni des extraits substantiels de ce document, ne doivent être imprimés ou autrement reproduits sans l’autorisation de l’auteur. Afin de se conformer à la Loi canadienne sur la protection des renseignements personnels, quelques formulaires secondaires, coordonnées ou signatures intégrées au texte ont pu être enlevés de ce document. Bien que cela ait pu affecter la pagination, il n’y a aucun contenu manquant. NOTICE The author of this thesis or dissertation has granted a nonexclusive license allowing Université de Montréal to reproduce and publish the document, in part or in whole, and in any format, solely for noncommercial educational and research purposes. -
JRASC, Dec. 2014
The Journal of The Royal Astronomical Society of Canada PROMOTING ASTRONOMY IN CANADA December/décembre 2014 Volume/volume 108 Le Journal de la Société royale d’astronomie du Canada Number/numéro 6 [769] Inside this issue: Citizen Science on the Faroe Islands GrayStar: A Web Application Deep-Sky Imaging Theory on the Origin of Aristarchos’s 87 Degrees Antares Palette The Best of Monochrome. Drawings, images in black and white, or narrow-band photography. For the last several months, Ron Brecher has been shooting faint objects from the Sharpless Catalog. This Hα image shows the very interesting Sh2-86 (aka NGC 6820), a large emission nebula in Vulpecula. The roundish central nebula is about the size of the full Moon on the sky. The long, dark finger in the middle of the nebula is similar to that in the Eagle Nebula, which is sometimes called “The Pillars of Creation.” Ron acquired this image under full Moon conditions using an SBIG STL-11000 camera on a 10-inch ASA Newtonian reflector at ƒ/6.8. Exposure was 42×10m + 3×20m αH (a total of 8 hr). Decembre/décembre 2014 | Vol. 108, No. 6 | Whole Number 769 contents / table des matières Feature Articles / Articles de fond Departments / Départements 230 Citizen Science on the Faroe Islands in Advance 226 President’s Corner of an Eclipse by James Edgar by Geoff Sims and Kate Russo 227 RASC Board of Directors and Office Staff 2014 235 GrayStar: A Web Application For Pedagogical 228 News Notes/En manchettes Stellar Atmosphere and Spectral-Line Modelling Compiled by Andrew I.