The Hertzsprung-Russell Diagram
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Commission 27 of the Iau Information Bulletin
COMMISSION 27 OF THE I.A.U. INFORMATION BULLETIN ON VARIABLE STARS Nos. 2401 - 2500 1983 September - 1984 March EDITORS: B. SZEIDL AND L. SZABADOS, KONKOLY OBSERVATORY 1525 BUDAPEST, Box 67, HUNGARY HU ISSN 0374-0676 CONTENTS 2401 A POSSIBLE CATACLYSMIC VARIABLE IN CANCER Masaaki Huruhata 20 September 1983 2402 A NEW RR-TYPE VARIABLE IN LEO Masaaki Huruhata 20 September 1983 2403 ON THE DELTA SCUTI STAR BD +43d1894 A. Yamasaki, A. Okazaki, M. Kitamura 23 September 1983 2404 IQ Vel: IMPROVED LIGHT-CURVE PARAMETERS L. Kohoutek 26 September 1983 2405 FLARE ACTIVITY OF EPSILON AURIGAE? I.-S. Nha, S.J. Lee 28 September 1983 2406 PHOTOELECTRIC OBSERVATIONS OF 20 CVn Y.W. Chun, Y.S. Lee, I.-S. Nha 30 September 1983 2407 MINIMUM TIMES OF THE ECLIPSING VARIABLES AH Cep AND IU Aur Pavel Mayer, J. Tremko 4 October 1983 2408 PHOTOELECTRIC OBSERVATIONS OF THE FLARE STAR EV Lac IN 1980 G. Asteriadis, S. Avgoloupis, L.N. Mavridis, P. Varvoglis 6 October 1983 2409 HD 37824: A NEW VARIABLE STAR Douglas S. Hall, G.W. Henry, H. Louth, T.R. Renner 10 October 1983 2410 ON THE PERIOD OF BW VULPECULAE E. Szuszkiewicz, S. Ratajczyk 12 October 1983 2411 THE UNIQUE DOUBLE-MODE CEPHEID CO Aur E. Antonello, L. Mantegazza 14 October 1983 2412 FLARE STARS IN TAURUS A.S. Hojaev 14 October 1983 2413 BVRI PHOTOMETRY OF THE ECLIPSING BINARY QX Cas Thomas J. Moffett, T.G. Barnes, III 17 October 1983 2414 THE ABSOLUTE MAGNITUDE OF AZ CANCRI William P. Bidelman, D. Hoffleit 17 October 1983 2415 NEW DATA ABOUT THE APSIDAL MOTION IN THE SYSTEM OF RU MONOCEROTIS D.Ya. -
Stellar Populations in a Standard ISOGAL Field in the Galactic Disc
A&A 493, 785–807 (2009) Astronomy DOI: 10.1051/0004-6361:200809668 & c ESO 2009 Astrophysics Stellar populations in a standard ISOGAL field in the Galactic disc, S. Ganesh1,2,A.Omont1,U.C.Joshi2,K.S.Baliyan2, M. Schultheis3,1,F.Schuller4,1,andG.Simon5 1 Institut d’Astrophysique de Paris, CNRS and Université Paris 6, 98bis boulevard Arago, 75014 Paris, France e-mail: [email protected] 2 Physical Research Laboratory, Navrangpura, Ahmedabad-380 009, India e-mail: [email protected] 3 Observatoire de Besançon, Besançon, France 4 Max-Planck-Institut fur Radioastronomie, Auf dem Hugel 69, 53121 Bonn, Germany 5 GEPI, UMS-CNRS 2201, Observatoire de Paris, France Received 28 February 2008 / Accepted 3 September 2008 ABSTRACT Aims. We identify the stellar populations (mostly red giants and young stars) detected in the ISOGAL survey at 7 and 15 μmtowards a field (LN45) in the direction = −45, b = 0.0. Methods. The sources detected in the survey of the Galactic plane by the Infrared Space Observatory were characterised based on colour−colour and colour−magnitude diagrams. We combine the ISOGAL catalogue with the data from surveys such as 2MASS and GLIMPSE. Interstellar extinction and distance were estimated using the red clump stars detected by 2MASS in combination with the isochrones for the AGB/RGB branch. Absolute magnitudes were thus derived and the stellar populations identified from their absolute magnitudes and their infrared excess. Results. A standard approach to analysing the ISOGAL disc observations has been established. We identify several hundred RGB/AGB stars and 22 candidate young stellar objects in the direction of this field in an area of 0.16 deg2. -
Galaxies – AS 3011
Galaxies – AS 3011 Simon Driver [email protected] ... room 308 This is a Junior Honours 18-lecture course Lectures 11am Wednesday & Friday Recommended book: The Structure and Evolution of Galaxies by Steven Phillipps Galaxies – AS 3011 1 Aims • To understand: – What is a galaxy – The different kinds of galaxy – The optical properties of galaxies – The hidden properties of galaxies such as dark matter, presence of black holes, etc. – Galaxy formation concepts and large scale structure • Appreciate: – Why galaxies are interesting, as building blocks of the Universe… and how simple calculations can be used to better understand these systems. Galaxies – AS 3011 2 1 from 1st year course: • AS 1001 covered the basics of : – distances, masses, types etc. of galaxies – spectra and hence dynamics – exotic things in galaxies: dark matter and black holes – galaxies on a cosmological scale – the Big Bang • in AS 3011 we will study dynamics in more depth, look at other non-stellar components of galaxies, and introduce high-redshift galaxies and the large-scale structure of the Universe Galaxies – AS 3011 3 Outline of lectures 1) galaxies as external objects 13) large-scale structure 2) types of galaxy 14) luminosity of the Universe 3) our Galaxy (components) 15) primordial galaxies 4) stellar populations 16) active galaxies 5) orbits of stars 17) anomalies & enigmas 6) stellar distribution – ellipticals 18) revision & exam advice 7) stellar distribution – spirals 8) dynamics of ellipticals plus 3-4 tutorials 9) dynamics of spirals (questions set after -
A Secondary Clump of Red Giant Stars: Why and Where
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server A secondary clump of red giant stars: why and where L´eo Girardi Max-Planck-Institut f¨ur Astrophysik, Karl-Schwarzschild-Str. 1, D-85740 Garching bei M¨unchen, Germany E-mail: [email protected] submitted to Monthly Notices of the Royal Astronomical Society Abstract. Based on the results of detailed population synthesis models, Girardi et al. (1998) recently claimed that the clump of red giants in the colour–magnitude diagram (CMD) of composite stellar populations should present an extension to lower luminosities, which goes down to about 0.4 mag below the main clump. This feature is made of stars just massive enough for having ignited helium in non- degenerate conditions, and therefore corresponds to a limited interval of stellar masses and ages. In the present models, which include moderate convective over- shooting, it corresponds to 1 Gyr old populations. In this paper, we go into∼ more details about the origin and properties of this feature. We first compare the clump theoretical models with data for clusters of different ages and metallicities, basically confirming the predicted behaviours. We then refine the previous models in order to show that: (i) The faint extension is expected to be clearly separated from the main clump in the CMD of metal-rich populations, defining a ‘secondary clump’ by itself. (ii) It should be present in all galactic fields containing 1 Gyr old stars and with mean metallicities higher than about Z =0:004. -
A Magnetar Model for the Hydrogen-Rich Super-Luminous Supernova Iptf14hls Luc Dessart
A&A 610, L10 (2018) https://doi.org/10.1051/0004-6361/201732402 Astronomy & © ESO 2018 Astrophysics LETTER TO THE EDITOR A magnetar model for the hydrogen-rich super-luminous supernova iPTF14hls Luc Dessart Unidad Mixta Internacional Franco-Chilena de Astronomía (CNRS, UMI 3386), Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile e-mail: [email protected] Received 2 December 2017 / Accepted 14 January 2018 ABSTRACT Transient surveys have recently revealed the existence of H-rich super-luminous supernovae (SLSN; e.g., iPTF14hls, OGLE-SN14-073) that are characterized by an exceptionally high time-integrated bolometric luminosity, a sustained blue optical color, and Doppler- broadened H I lines at all times. Here, I investigate the effect that a magnetar (with an initial rotational energy of 4 × 1050 erg and 13 field strength of 7 × 10 G) would have on the properties of a typical Type II supernova (SN) ejecta (mass of 13.35 M , kinetic 51 56 energy of 1:32 × 10 erg, 0.077 M of Ni) produced by the terminal explosion of an H-rich blue supergiant star. I present a non-local thermodynamic equilibrium time-dependent radiative transfer simulation of the resulting photometric and spectroscopic evolution from 1 d until 600 d after explosion. With the magnetar power, the model luminosity and brightness are enhanced, the ejecta is hotter and more ionized everywhere, and the spectrum formation region is much more extended. This magnetar-powered SN ejecta reproduces most of the observed properties of SLSN iPTF14hls, including the sustained brightness of −18 mag in the R band, the blue optical color, and the broad H I lines for 600 d. -
Arxiv:1712.02405V2 [Astro-Ph.SR] 11 Dec 2017
Draft version October 19, 2018 Typeset using LATEX twocolumn style in AASTeX61 PHOTOSPHERIC DIAGNOSTICS OF CORE HELIUM BURNING IN GIANT STARS Keith Hawkins,1 Yuan-Sen Ting,2, 3, 4, 5 and Hans-Walter Rix6 1Department of Astronomy, Columbia University, 550 W 120th St, New York, NY 10027, USA 2Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, The Australian National University, ACT 2611, Australia 3Institute for Advanced Study, Princeton, NJ 08540, USA 4Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA 5Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101, USA 6Max-Planck-Institut f¨urAstronomie, K¨onigstuhl17, D-69117 Heidelberg, Germany ABSTRACT Core helium burning primary red clump (RC) stars are evolved red giant stars which are excellent standard candles. As such, these stars are routinely used to map the Milky Way or determine the distance to other galaxies among other things. However distinguishing RC stars from their less evolved precursors, namely red giant branch (RGB) stars, is still a difficult challenge and has been deemed the domain of asteroseismology. In this letter, we use a sample of 1,676 RGB and RC stars which have both single epoch infrared spectra from the APOGEE survey and asteroseismic parameters and classification to show that the spectra alone can be used to (1) predict asteroseismic parameters with precision high enough to (2) distinguish core helium burning RC from other giant stars with less than 2% contamination. This will not only allow for a clean selection of a large number of standard candles across our own and other galaxies from spectroscopic surveys, but also will remove one of the primary roadblocks for stellar evolution studies of mixing and mass loss in red giant stars. -
Stellar Evolution
Stellar Astrophysics: Stellar Evolution 1 Stellar Evolution Update date: December 14, 2010 With the understanding of the basic physical processes in stars, we now proceed to study their evolution. In particular, we will focus on discussing how such processes are related to key characteristics seen in the HRD. 1 Star Formation From the virial theorem, 2E = −Ω, we have Z M 3kT M GMr = dMr (1) µmA 0 r for the hydrostatic equilibrium of a gas sphere with a total mass M. Assuming that the density is constant, the right side of the equation is 3=5(GM 2=R). If the left side is smaller than the right side, the cloud would collapse. For the given chemical composition, ρ and T , this criterion gives the minimum mass (called Jeans mass) of the cloud to undergo a gravitational collapse: 3 1=2 5kT 3=2 M > MJ ≡ : (2) 4πρ GµmA 5 For typical temperatures and densities of large molecular clouds, MJ ∼ 10 M with −1=2 a collapse time scale of tff ≈ (Gρ) . Such mass clouds may be formed in spiral density waves and other density perturbations (e.g., caused by the expansion of a supernova remnant or superbubble). What exactly happens during the collapse depends very much on the temperature evolution of the cloud. Initially, the cooling processes (due to molecular and dust radiation) are very efficient. If the cooling time scale tcool is much shorter than tff , −1=2 the collapse is approximately isothermal. As MJ / ρ decreases, inhomogeneities with mass larger than the actual MJ will collapse by themselves with their local tff , different from the initial tff of the whole cloud. -
Evolution of Thermally Pulsing Asymptotic Giant Branch Stars
The Astrophysical Journal, 822:73 (15pp), 2016 May 10 doi:10.3847/0004-637X/822/2/73 © 2016. The American Astronomical Society. All rights reserved. EVOLUTION OF THERMALLY PULSING ASYMPTOTIC GIANT BRANCH STARS. V. CONSTRAINING THE MASS LOSS AND LIFETIMES OF INTERMEDIATE-MASS, LOW-METALLICITY AGB STARS* Philip Rosenfield1,2,7, Paola Marigo2, Léo Girardi3, Julianne J. Dalcanton4, Alessandro Bressan5, Benjamin F. Williams4, and Andrew Dolphin6 1 Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA 2 Department of Physics and Astronomy G. Galilei, University of Padova, Vicolo dell’Osservatorio 3, I-35122 Padova, Italy 3 Osservatorio Astronomico di Padova—INAF, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy 4 Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA 5 Astrophysics Sector, SISSA, Via Bonomea 265, I-34136 Trieste, Italy 6 Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756, USA Received 2016 January 1; accepted 2016 March 14; published 2016 May 6 ABSTRACT Thermally pulsing asymptotic giant branch (TP-AGB) stars are relatively short lived (less than a few Myr), yet their cool effective temperatures, high luminosities, efficient mass loss, and dust production can dramatically affect the chemical enrichment histories and the spectral energy distributions of their host galaxies. The ability to accurately model TP-AGB stars is critical to the interpretation of the integrated light of distant galaxies, especially in redder wavelengths. We continue previous efforts to constrain the evolution and lifetimes of TP-AGB stars by modeling their underlying stellar populations. Using Hubble Space Telescope (HST) optical and near-infrared photometry taken of 12 fields of 10 nearby galaxies imaged via the Advanced Camera for Surveys Nearby Galaxy Survey Treasury and the near-infrared HST/SNAP follow-up campaign, we compare the model and observed TP- AGB luminosity functions as well as the ratio of TP-AGB to red giant branch stars. -
PHAS 1102 Physics of the Universe 3 – Magnitudes and Distances
PHAS 1102 Physics of the Universe 3 – Magnitudes and distances Brightness of Stars • Luminosity – amount of energy emitted per second – not the same as how much we observe! • We observe a star’s apparent brightness – Depends on: • luminosity • distance – Brightness decreases as 1/r2 (as distance r increases) • other dimming effects – dust between us & star Defining magnitudes (1) Thus Pogson formalised the magnitude scale for brightness. This is the brightness that a star appears to have on the sky, thus it is referred to as apparent magnitude. Also – this is the brightness as it appears in our eyes. Our eyes have their own response to light, i.e. they act as a kind of filter, sensitive over a certain wavelength range. This filter is called the visual band and is centred on ~5500 Angstroms. Thus these are apparent visual magnitudes, mv Related to flux, i.e. energy received per unit area per unit time Defining magnitudes (2) For example, if star A has mv=1 and star B has mv=6, then 5 mV(B)-mV(A)=5 and their flux ratio fA/fB = 100 = 2.512 100 = 2.512mv(B)-mv(A) where !mV=1 corresponds to a flux ratio of 1001/5 = 2.512 1 flux(arbitrary units) 1 6 apparent visual magnitude, mv From flux to magnitude So if you know the magnitudes of two stars, you can calculate mv(B)-mv(A) the ratio of their fluxes using fA/fB = 2.512 Conversely, if you know their flux ratio, you can calculate the difference in magnitudes since: 2.512 = 1001/5 log (f /f ) = [m (B)-m (A)] log 2.512 10 A B V V 10 = 102/5 = 101/2.5 mV(B)-mV(A) = !mV = 2.5 log10(fA/fB) To calculate a star’s apparent visual magnitude itself, you need to know the flux for an object at mV=0, then: mS - 0 = mS = 2.5 log10(f0) - 2.5 log10(fS) => mS = - 2.5 log10(fS) + C where C is a constant (‘zero-point’), i.e. -
Arxiv:1803.04461V1 [Astro-Ph.SR] 12 Mar 2018 (Received; Revised March 14, 2018) Submitted to Apj
Draft version March 14, 2018 Typeset using LATEX preprint style in AASTeX61 CHEMICAL ABUNDANCES OF MAIN-SEQUENCE, TURN-OFF, SUBGIANT AND RED GIANT STARS FROM APOGEE SPECTRA I: SIGNATURES OF DIFFUSION IN THE OPEN CLUSTER M67 Diogo Souto,1 Katia Cunha,2, 1 Verne V. Smith,3 C. Allende Prieto,4, 5 D. A. Garc´ıa-Hernandez,´ 4, 5 Marc Pinsonneault,6 Parker Holzer,7 Peter Frinchaboy,8 Jon Holtzman,9 J. A. Johnson,6 Henrik Jonsson¨ ,10 Steven R. Majewski,11 Matthew Shetrone,12 Jennifer Sobeck,11 Guy Stringfellow,13 Johanna Teske,14 Olga Zamora,4, 5 Gail Zasowski,7 Ricardo Carrera,15 Keivan Stassun,16 J. G. Fernandez-Trincado,17, 18 Sandro Villanova,17 Dante Minniti,19 and Felipe Santana20 1Observat´orioNacional, Rua General Jos´eCristino, 77, 20921-400 S~aoCrist´ov~ao,Rio de Janeiro, RJ, Brazil 2Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065, USA 3National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA 4Instituto de Astrof´ısica de Canarias, E-38205 La Laguna, Tenerife, Spain 5Departamento de Astrof´ısica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain 6Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA 7Department of Physics and Astronomy, The University of Utah, Salt Lake City, UT 84112, USA 8Department of Physics & Astronomy, Texas Christian University, Fort Worth, TX, 76129, USA 9New Mexico State University, Las Cruces, NM 88003, USA 10Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, -
Abundance–Age Relations with Red Clump Stars in Open Clusters?,?? L
A&A 652, A25 (2021) Astronomy https://doi.org/10.1051/0004-6361/202039951 & c L. Casamiquela et al. 2021 Astrophysics Abundance–age relations with red clump stars in open clusters?,?? L. Casamiquela1, C. Soubiran1 , P. Jofré2 , C. Chiappini3, N. Lagarde4 , Y. Tarricq1 , R. Carrera5 , C. Jordi6 , L. Balaguer-Núñez6 , J. Carbajo-Hijarrubia6, and S. Blanco-Cuaresma7 1 Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France e-mail: [email protected] 2 Núcleo de Astronomía, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército 441, Santiago, Chile 3 Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany 4 Institut UTINAM, CNRS UMR6213, Univ. Bourgogne Franche-Comté, OSU-THETA Franche-Comté-Bourgogne, Observatoire de Besançon, BP 1615, 25010 Besançon Cedex, France 5 INAF-Osservatorio Astronomico di Padova, vicolo dell’Osservatorio 5, 35122 Padova, Italy 6 Dept. FQA, Institut de Ciéncies del Cosmos (ICCUB), Universitat de Barcelona (IEEC-UB), Martí Franqués 1, 08028 Barcelona, Spain 7 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA Received 19 November 2020 / Accepted 14 May 2021 ABSTRACT Context. Precise chemical abundances coupled with reliable ages are key ingredients to understanding the chemical history of our Galaxy. Open clusters (OCs) are useful for this purpose because they provide ages with good precision. Aims. The aim of this work is to investigate the relation between different chemical abundance ratios and age traced by red clump (RC) stars in OCs. Methods. We analyzed a large sample of 209 reliable members in 47 OCs with available high-resolution spectroscopy. -
The H and G Magnitude System for Asteroids
Meetings The BAA Observers’ Workshops The H and G magnitude system for asteroids This article is based on a presentation given at the Observers’ Workshop held at the Open University in Milton Keynes on 2007 February 24. It can be viewed on the Asteroids & Remote Planets Section website at http://homepage.ntlworld.com/ roger.dymock/index.htm When you look at an asteroid through the eyepiece of a telescope or on a CCD image it is a rather unexciting point of light. However by analysing a number of images, information on the nature of the object can be gleaned. Frequent (say every minute or few min- Figure 2. The inclined orbit of (23) Thalia at opposition. utes) measurements of magnitude over periods of several hours can be used to generate a lightcurve. Analysis of such a lightcurve Absolute magnitude, H: the V-band magnitude of an asteroid if yields the period, shape and pole orientation of the object. it were 1 AU from the Earth and 1 AU from the Sun and fully Measurements of position (astrometry) can be used to calculate illuminated, i.e. at zero phase angle (actually a geometrically the orbit of the asteroid and thus its distance from the Earth and the impossible situation). H can be calculated from the equation Sun at the time of the observations. These distances must be known H = H(α) + 2.5log[(1−G)φ (α) + G φ (α)], where: in order for the absolute magnitude, H and the slope parameter, G 1 2 φ (α) = exp{−A (tan½ α)Bi} to be calculated (it is common for G to be given a nominal value of i i i = 1 or 2, A = 3.33, A = 1.87, B = 0.63 and B = 1.22 0.015).