Spectroscopic Confirmation of the Sixth Globular Cluster in the Fornax
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Tidal Disruption of Globular Clusters in Dwarf Galaxies with Triaxial Dark Matter Haloes.” by J
“Tidal disruption of globular clusters in dwarf galaxies with triaxial dark matter haloes.” by J. Peñarrubia, M.J. Walker, and G. Gilmore University of Cambridge and University of Victoria MNRAS accepted Journal Club 5/15/09 Daniel Grin 1/19 Wednesday, September 2, 2009 1 Punchline 2/19 • Globular clusters (GCs) around dwarf spheroidal (dSph) galaxies may survive tidal encounters • Stellar substructure (morphology and kinematics) in dSph galaxies may be explained by past disruptions of GCs • Simulation techniques grossly over-simplify the problem, but useful first step Wednesday, September 2, 2009 2 Outline 3/19 • Motivation: subtructure in dSphs and existence of GCs near them. • Properties of systems modeled • Simulation techniques/caveats • Results Wednesday, September 2, 2009 3 Motivation: Substructure in dSph galaxies 4/19 • Milky Way (MW) dSph galaxies are DM dominated-- : • Ideal testbed for CDM scenario • Standing dispute about presence of cores (triaxiality? projection effect? see work by J. Simon) • dSph galaxies have substructure, contrary to expectation that it should be erased in a few crossing times (~100 Myr): • Morphology: Kinematically cold core in Sextans, kinematically distinct shell in Fornax, asymmetries across major/minor axes in Fornax (claims of butterfly shapes are sketchy) • Ages: 2 Gyr-old stellar populations in Fornax shell • Can prolong life of stellar substructure with cored density profile, challenge to CDM? • Can save CDM with formation of substructure that is not in situ • Blue stragglers in Sextans are mass segregated, not enough time for this in Sextans, do it elsewhere (like a merging G.C.) and disrupt? Wednesday, September 2, 2009 4 Motivation: Globular clusters in dSph 5/19 • Fornax (5) and Sagitarrius (4) contain GCs near : Name Angular sep. -
The Dunhuang Chinese Sky: a Comprehensive Study of the Oldest Known Star Atlas
25/02/09JAHH/v4 1 THE DUNHUANG CHINESE SKY: A COMPREHENSIVE STUDY OF THE OLDEST KNOWN STAR ATLAS JEAN-MARC BONNET-BIDAUD Commissariat à l’Energie Atomique ,Centre de Saclay, F-91191 Gif-sur-Yvette, France E-mail: [email protected] FRANÇOISE PRADERIE Observatoire de Paris, 61 Avenue de l’Observatoire, F- 75014 Paris, France E-mail: [email protected] and SUSAN WHITFIELD The British Library, 96 Euston Road, London NW1 2DB, UK E-mail: [email protected] Abstract: This paper presents an analysis of the star atlas included in the medieval Chinese manuscript (Or.8210/S.3326), discovered in 1907 by the archaeologist Aurel Stein at the Silk Road town of Dunhuang and now held in the British Library. Although partially studied by a few Chinese scholars, it has never been fully displayed and discussed in the Western world. This set of sky maps (12 hour angle maps in quasi-cylindrical projection and a circumpolar map in azimuthal projection), displaying the full sky visible from the Northern hemisphere, is up to now the oldest complete preserved star atlas from any civilisation. It is also the first known pictorial representation of the quasi-totality of the Chinese constellations. This paper describes the history of the physical object – a roll of thin paper drawn with ink. We analyse the stellar content of each map (1339 stars, 257 asterisms) and the texts associated with the maps. We establish the precision with which the maps are drawn (1.5 to 4° for the brightest stars) and examine the type of projections used. -
Axions and Other Similar Particles
1 91. Axions and Other Similar Particles 91. Axions and Other Similar Particles Revised October 2019 by A. Ringwald (DESY, Hamburg), L.J. Rosenberg (U. Washington) and G. Rybka (U. Washington). 91.1 Introduction In this section, we list coupling-strength and mass limits for light neutral scalar or pseudoscalar bosons that couple weakly to normal matter and radiation. Such bosons may arise from the spon- taneous breaking of a global U(1) symmetry, resulting in a massless Nambu-Goldstone (NG) boson. If there is a small explicit symmetry breaking, either already in the Lagrangian or due to quantum effects such as anomalies, the boson acquires a mass and is called a pseudo-NG boson. Typical examples are axions (A0)[1–4] and majorons [5], associated, respectively, with a spontaneously broken Peccei-Quinn and lepton-number symmetry. A common feature of these light bosons φ is that their coupling to Standard-Model particles is suppressed by the energy scale that characterizes the symmetry breaking, i.e., the decay constant f. The interaction Lagrangian is −1 µ L = f J ∂µ φ , (91.1) where J µ is the Noether current of the spontaneously broken global symmetry. If f is very large, these new particles interact very weakly. Detecting them would provide a window to physics far beyond what can be probed at accelerators. Axions are of particular interest because the Peccei-Quinn (PQ) mechanism remains perhaps the most credible scheme to preserve CP-symmetry in QCD. Moreover, the cold dark matter (CDM) of the universe may well consist of axions and they are searched for in dedicated experiments with a realistic chance of discovery. -
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. -
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. -
Memoria De Publicaciones 2017 Facultad De Ciencias Uam Memoria De Publicaciones De La Facultad De Ciencias 2017
MEMORIA DE PUBLICACIONES 2017 FACULTAD DE CIENCIAS UAM MEMORIA DE PUBLICACIONES DE LA FACULTAD DE CIENCIAS 2017 La Memoria de Publicaciones de la Facultad de Ciencias, como parte de la Memoria de Investigación, aspira a dar cuenta de los resultados de la investigación realizada a lo largo de 2017 por los profesores e investigadores de la Facultad. Ha sido realizada por la Biblioteca de Ciencias contando con las aportaciones facilitadas por los Departamentos y por el Decanato de la Facultad, en la persona de la Vicedecana de Investigación, a quienes agradecemos enormemente su aportación. Publicaciones en La Facultad ha generado un volumen de producción científica 2017 de 1.267 publicaciones 1.104 En 2017 se han publicado un total de 1.104 trabajos citables Trabajos Citables (entre artículos y revisiones) de los que 1.056 tienen Factor de Impacto calculado (96%) 73% La Facultad de Ciencias tiene un total de 807 trabajos Trabajos indexados en Q1, que supone el 73,10% del total de los Primer Cuartil – Q1 trabajos publicados, prácticamente igual que el año anterior. Algunos departamentos superan este porcentaje situándose entre el 85% y 96% 1 La Facultad de Ciencias tiene al único investigador de la UAM Highly Cited considerado como investigador altamente citado para el año Researchers 2017 en el área de Física, según los listados de Clarivate Analytics, elaborados a partir de la Web of Science. https://clarivate.com/hcr/researchers-list/archived-lists/ : es el profesor Francisco José García Vidal, del Departamento de Física Teórica de la Materia Condensada. Memoria de Publicaciones de la Facultad de Ciencias 2017 Página 2 de 146 ÍNDICE . -
Young Globular Clusters and Dwarf Spheroidals
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server Young Globular Clusters and Dwarf Spheroidals Sidney van den Bergh Dominion Astrophysical Observatory Herzberg Institute of Astrophysics National Research Council of Canada 5071 West Saanich Road Victoria, British Columbia, V8X 4M6 Canada ABSTRACT Most of the globular clusters in the main body of the Galactic halo were formed almost simultaneously. However, globular cluster formation in dwarf spheroidal galaxies appears to have extended over a significant fraction of a Hubble time. This suggests that the factors which suppressed late-time formation of globulars in the main body of the Galactic halo were not operative in dwarf spheroidal galaxies. Possibly the presence of significant numbers of “young” globulars at RGC > 15 kpc can be accounted for by the assumption that many of these objects were formed in Sagittarius-like (but not Fornax-like) dwarf spheroidal galaxies, that were subsequently destroyed by Galactic tidal forces. It would be of interest to search for low-luminosity remnants of parental dwarf spheroidals around the “young” globulars Eridanus, Palomar 1, 3, 14, and Terzan 7. Furthermore multi-color photometry could be used to search for the remnants of the super-associations, within which outer halo globular clusters originally formed. Such envelopes are expected to have been tidally stripped from globulars in the inner halo. Subject headings: Globular clusters - galaxies: dwarf The galaxy is, in fact, nothing but a congeries of innumerable stars grouped together in clusters. Galileo (1610) –2– 1. Introduction The vast majority of Galactic globular clusters appear to have formed at about the same time (e.g. -
Eight New Milky Way Companions Discovered in FirstYear Dark Energy Survey Data
Eight new Milky Way companions discovered in first-year Dark Energy Survey Data Article (Published Version) Romer, Kathy and The DES Collaboration, et al (2015) Eight new Milky Way companions discovered in first-year Dark Energy Survey Data. Astrophysical Journal, 807 (1). ISSN 0004- 637X This version is available from Sussex Research Online: http://sro.sussex.ac.uk/id/eprint/61756/ This document is made available in accordance with publisher policies and may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher’s version. Please see the URL above for details on accessing the published version. Copyright and reuse: Sussex Research Online is a digital repository of the research output of the University. Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available. Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. http://sro.sussex.ac.uk The Astrophysical Journal, 807:50 (16pp), 2015 July 1 doi:10.1088/0004-637X/807/1/50 © 2015. -
Astro-Ph.GA] 28 May 2015
SLAC-PUB-16746 Eight New Milky Way Companions Discovered in First-Year Dark Energy Survey Data K. Bechtol1;y, A. Drlica-Wagner2;y, E. Balbinot3;4, A. Pieres5;4, J. D. Simon6, B. Yanny2, B. Santiago5;4, R. H. Wechsler7;8;11, J. Frieman2;1, A. R. Walker9, P. Williams1, E. Rozo10;11, E. S. Rykoff11, A. Queiroz5;4, E. Luque5;4, A. Benoit-L´evy12, D. Tucker2, I. Sevilla13;14, R. A. Gruendl15;13, L. N. da Costa16;4, A. Fausti Neto4, M. A. G. Maia4;16, T. Abbott9, S. Allam17;2, R. Armstrong18, A. H. Bauer19, G. M. Bernstein18, R. A. Bernstein6, E. Bertin20;21, D. Brooks12, E. Buckley-Geer2, D. L. Burke11, A. Carnero Rosell4;16, F. J. Castander19, R. Covarrubias15, C. B. D'Andrea22, D. L. DePoy23, S. Desai24;25, H. T. Diehl2, T. F. Eifler26;18, J. Estrada2, A. E. Evrard27, E. Fernandez28;39, D. A. Finley2, B. Flaugher2, E. Gaztanaga19, D. Gerdes27, L. Girardi16, M. Gladders29;1, D. Gruen30;31, G. Gutierrez2, J. Hao2, K. Honscheid32;33, B. Jain18, D. James9, S. Kent2, R. Kron1, K. Kuehn34;35, N. Kuropatkin2, O. Lahav12, T. S. Li23, H. Lin2, M. Makler36, M. March18, J. Marshall23, P. Martini33;37, K. W. Merritt2, C. Miller27;38, R. Miquel28;39, J. Mohr24, E. Neilsen2, R. Nichol22, B. Nord2, R. Ogando4;16, J. Peoples2, D. Petravick15, A. A. Plazas40;26, A. K. Romer41, A. Roodman7;11, M. Sako18, E. Sanchez14, V. Scarpine2, M. Schubnell27, R. C. Smith9, M. Soares-Santos2, F. Sobreira2;4, E. Suchyta32;33, M. E. C. Swanson15, G. -
Galactic Metal-Poor Halo E NCYCLOPEDIA of a STRONOMY and a STROPHYSICS
Galactic Metal-Poor Halo E NCYCLOPEDIA OF A STRONOMY AND A STROPHYSICS Galactic Metal-Poor Halo Most of the gas, stars and clusters in our Milky Way Galaxy are distributed in its rotating, metal-rich, gas-rich and flattened disk and in the more slowly rotating, metal- rich and gas-poor bulge. The Galaxy’s halo is roughly spheroidal in shape, and extends, with decreasing density, out to distances comparable with those of the Magellanic Clouds and the dwarf spheroidal galaxies that have been collected around the Galaxy. Aside from its roughly spheroidal distribution, the most salient general properties of the halo are its low metallicity relative to the bulk of the Galaxy’s stars, its lack of a gaseous counterpart, unlike the Galactic disk, and its great age. The kinematics of the stellar halo is closely coupled to the spheroidal distribution. Solar neighborhood disk stars move at a speed of about 220 km s−1 toward a point in the plane ◦ and 90 from the Galactic center. Stars belonging to the spheroidal halo do not share such ordered motion, and thus appear to have ‘high velocities’ relative to the Sun. Their orbital energies are often comparable with those of the disk stars but they are directed differently, often on orbits that have a smaller component of rotation or angular Figure 1. The distribution of [Fe/H] values for globular clusters. momentum. Following the original description by Baade in 1944, the disk stars are often called POPULATION I while still used to measure R . The recognizability of globular the metal-poor halo stars belong to POPULATION II. -
Classical Images – Greek Pegasus
Classical images – Greek Pegasus Red-figure kylix crater Attic Red-figure kylix Triptolemus Painter, c. 460 BC attr Skythes, c. 510 BC Edinburgh, National Museums of Scotland Boston, MFA (source: theoi.com) Faliscan black pottery kylix Athena with Pegasus on shield Black-figure water jar (Perseus on neck, Pegasus with Etrurian, attr. the Sokran Group, c. 350 BC Athenian black-figure amphora necklace of bullae (studs) and wings on feet, Centaur) London, The British Museum (1842.0407) attr. Kleophrades pntr., 5th C BC From Vulci, attr. Micali painter, c. 510-500 BC 1 New York, Metropolitan Museum of ART (07.286.79) London, The British Museum (1836.0224.159) Classical images – Greek Pegasus Pegasus Pegasus Attic, red-figure plate, c. 420 BC Source: Wikimedia (Rome, Palazzo Massimo exh) 2 Classical images – Greek Pegasus Pegasus London, The British Museum Virginia, Museum of Fine Arts exh (The Horse in Art) Pegasus Red-figure oinochoe Apulian, c. 320-10 BC 3 Boston, MFA Classical images – Greek Pegasus Silver coin (Pegasus and Athena) Silver coin (Pegasus and Lion/Bull combat) Corinth, c. 415-387 BC Lycia, c. 500-460 BC London, The British Museum (Ac RPK.p6B.30 Cor) London, The British Museum (Ac 1979.0101.697) Silver coin (Pegasus protome and Warrior (Nergal?)) Silver coin (Arethusa and Pegasus Levantine, 5th-4th C BC Graeco-Iberian, after 241 BC London, The British Museum (Ac 1983, 0533.1) London, The British Museum (Ac. 1987.0649.434) 4 Classical images – Greek (winged horses) Pegasus Helios (Sol-Apollo) in his chariot Eos in her chariot Attic kalyx-krater, c. -
Kiski Astronomers at Cherry Springs: Perseids - August, 2015
Kiski Astronomers at Cherry Springs: Perseids - August, 2015 After finishing my trip to the Lehigh Valley Amateur Astronomical Society ’s Pulpit Rock Observatory the weekend of August 7 th – 9th, I headed over to Cherry Springs to take in the annual Perseid Meteor shower with several other members of the Kiski Astronomers. Monday 08/10/2015: Leaving a damp Pulpit Rock behind, I made the 3 hour drive from Eastern PA to the Astronomers Paradise – Cherry Springs State Park. Arrived late afternoon to find Bob K already there, and setup my camp across from him. Assembled the telescope, but wasn’t able to do much more, as clouds rolled in at sunset. Headed inside to read and early to bed. Tuesday 08/11/2015: Spent the day setting up a few more camping items and visiting with Bob N from the Kiski Club and Mike P from Niagara Canada who arrived and setup with us, and planning for the observing that evening. The sky stayed clear for the afternoon, and once the sun went down, we all got to work. Using my StellaCam-3 videocamera and 8” SCT optical tube on a C-Gem mount, I started working thru my constellation survey, chasing faint galaxies in Ursa Major. These included NGC-3065 & 3066, 3259, 3348, and 3516. Would like to have gone after more galaxies in the Great Bear, but he was too low in the tree tops. Have to wait till next year to re -visit that dipper! I then chased down the faint and elusive globular cluster Palomar -12 in Capricornus.