The Ellipticities of Globular Clusters in the Andromeda Galaxy
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The Most Massive Star Cluster in the Local Group
This is a repository copy of A 'super' star cluster grown old: the most massive star cluster in the Local Group. White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/144713/ Version: Published Version Article: Ma, J., De Grijs, R., Yang, Y. et al. (5 more authors) (2006) A 'super' star cluster grown old: the most massive star cluster in the Local Group. Monthly Notices of the Royal Astronomical Society , 368 (3). pp. 1443-1450. ISSN 0035-8711 https://doi.org/10.1111/j.1365-2966.2006.10231.x This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2006 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Reuse Items deposited in White Rose Research Online are protected by copyright, with all rights reserved unless indicated otherwise. They may be downloaded and/or printed for private study, or other acts as permitted by national copyright laws. The publisher or other rights holders may allow further reproduction and re-use of the full text version. This is indicated by the licence information on the White Rose Research Online record for the item. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ Mon. Not. R. Astron. Soc. 368, 1443–1450 (2006) doi:10.1111/j.1365-2966.2006.10231.x A ‘super’ star cluster grown old: the most massive star cluster in the Local Group J. -
5. Cosmic Distance Ladder Ii: Standard Candles
5. COSMIC DISTANCE LADDER II: STANDARD CANDLES EQUIPMENT Computer with internet connection GOALS In this lab, you will learn: 1. How to use RR Lyrae variable stars to measures distances to objects within the Milky Way galaxy. 2. How to use Cepheid variable stars to measure distances to nearby galaxies. 3. How to use Type Ia supernovae to measure distances to faraway galaxies. 1 BACKGROUND A. MAGNITUDES Astronomers use apparent magnitudes , which are often referred to simply as magnitudes, to measure brightness: The more negative the magnitude, the brighter the object. The more positive the magnitude, the fainter the object. In the following tutorial, you will learn how to measure, or photometer , uncalibrated magnitudes: http://skynet.unc.edu/ASTR101L/videos/photometry/ 2 In Afterglow, go to “File”, “Open Image(s)”, “Sample Images”, “Astro 101 Lab”, “Lab 5 – Standard Candles”, “CD-47” and open the image “CD-47 8676”. Measure the uncalibrated magnitude of star A: uncalibrated magnitude of star A: ____________________ Uncalibrated magnitudes are always off by a constant and this constant varies from image to image, depending on observing conditions among other things. To calibrate an uncalibrated magnitude, one must first measure this constant, which we do by photometering a reference star of known magnitude: uncalibrated magnitude of reference star: ____________________ 3 The known, true magnitude of the reference star is 12.01. Calculate the correction constant: correction constant = true magnitude of reference star – uncalibrated magnitude of reference star correction constant: ____________________ Finally, calibrate the uncalibrated magnitude of star A by adding the correction constant to it: calibrated magnitude = uncalibrated magnitude + correction constant calibrated magnitude of star A: ____________________ The true magnitude of star A is 13.74. -
New Globular Cluster Age Estimates and Constraints on the Cosmic Equation of State and the Matter Density of the Universe
1 New Globular Cluster Age Estimates and Constraints on the Cosmic Equation of State and The Matter Density of the Universe. Lawrence M. Krauss* & Brian Chaboyer *Departments of Physics and Astronomy, Case Western Reserve University, 10900 Euclid Ave., Cleveland OH USA 44106-7079; Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH. USA New estimates of globular cluster distances, combined with revised ranges for input parameters in stellar evolution codes and recent estimates of the earliest redshift of cluster formation allow us to derive a new 95% confidence level lower limit on the age of the Universe of 11 Gyr. This is now definitively inconsistent with the expansion age for a flat Universe for the currently allowed range of the Hubble constant unless the cosmic equation of state is dominated by a component that violates the strong energy condition. This solidifies the case for a dark energy-dominated universe, complementing supernova data and direct measurements of the geometry and matter density in the Universe. The best-fit age is consistent with a cosmological constant-dominated (w=pressure/energy density = -1) universe. For the Hubble Key project best fit value of the Hubble Ω Constant our age limits yields the constraints w < -0.4 and Ωmatter < 0.38 at the 68 Ω % confidence level, and w < -0.26 and Ωmatter < 0.58 at the 95 % confidence level. Age determinations of globular clusters provided one of the earliest motivations for considering the possible existence of a cosmological constant. By comparing a lower limit on the age of the oldest globular clusters in our galaxy--- estimated in the 1980 s to be 15-20 Gyr---with the expansion age, determined by measurements of the Hubble constant, an apparent inconsistency arose: globular clusters appeared to be older than 2 the Universe unless one allowed for a possible Cosmological Constant. -
Drilling Through the M31 Halo Near Mayall-II/G1
Drilling through the M31 Halo near Mayall-II/G1 Michael Gregg University of California, Davis Michael West Lowell Observatory Brian Lemaux University of California, Davis Andreas Küpper Quantco, Inc. Origin of the brightest Globulars Clusters Mayall-II/G1 in M31 Omega Cen in Milky Way •G1 has mass of ~107 M⊙ and σ = 25 km/s •High ellipticity, ~0.2, 50% rotationally supported •Metallicity spread, ~0.45 dex •Evidence for massive blackhole in the core, ~104 M⊙ •=> Former dwarf galaxy nucleus, now Ultra-Compact Dwarf? Origin of the brightest Globulars Clusters ...and connection to galaxy halo formation… HST image of nucleated Typical UCD (or bright globular) dwarf elliptical in in the same galaxy cluster: the Fornax galaxy cluster: possibly a tidally stripped nucleus nucleus + envelope of stars Origin of the brightest Globulars Clusters... Fornax Galaxy Cluster ...and connection to galaxy halo formation… image credit: M. Hilker •Evolved tidal streams are too faint (∼> 30 mag/sq.′′) to detect with standard imaging (Ibata et al. 2001; Ferguson et al. 2002; etc., etc., etc.) •Need resolved star spectroscopy to identify tidal debris; characteristics can perhaps can yield insight into the precursor of G1… G1 in Context Chemin et al. (2009) • We view G1 projected against the outer disk of M31, 2.6˚ (34 kpc) distant from the bulge. • The M31 disk has v < −500 km s-1 at G1 (Chemin et al. 2009). • G1 systemic v = −332 ± 3 km s-1 (Galleti et al. 2006), separation of ∼ 170 km s-1, 5-6 times the velocity dispersion of G1 or the M31 cold disk. -
Mayall II= G1 in M31: Giant Globular Cluster Or Core of a Dwarf Elliptical
Mayall II ≡ G1 in M31: Giant Globular Cluster or Core of a Dwarf Elliptical Galaxy? 1,2 G. Meylan3 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, U.S.A., email: [email protected], and European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei M¨unchen, Germany. A. Sarajedini University of Florida, Astronomy Department, Gainesville, FL 32611-2055, U.S.A. email: [email protected]fl.edu P. Jablonka DAEC-URA 8631, Observatoire de Paris-Meudon, Place Jules Janssen, F-92195 Meudon, France. email: [email protected] S. G. Djorgovski Palomar Observatory, MS 105–24, Caltech, Pasadena, CA 91125, U.S.A. email: [email protected] T. Bridges Anglo-Australian Observatory, PO Box 296, Epping, NSW 2121, Australia. email: [email protected] R. M. Rich UCLA, Physics & Astronomy Department, Math-Sciences 8979, Los Angeles, CA 90095-1562, U.S.A. email: [email protected] 1 Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associate with proposal IDs 5907 and 5464. arXiv:astro-ph/0105013v1 1 May 2001 2 Based in part on observations obtained at the W.M. Keck Observatory, which is operated jointly by the California Institute of Technology and the University of California. 3 Affiliated with the Astrophysics Division of the European Space Agency, ESTEC, Noordwijk, The Netherlands. ABSTRACT Mayall II ≡ G1 is one of the brightest globular clusters belonging to M31, the Andromeda galaxy. -
Sebastien GUILLOT Post-Doctoral Fellow at IRAP
Sebastien GUILLOT Post-doctoral Fellow at IRAP 9, avenue du Colonel Roche, BP 44346. 31028 Toulouse Cedex 4 [email protected] Citizenship: French Date of birth: August 6th, 1984 www.astro.puc.cl/~sguillot/ Research Interests Neutron stars, dense matter physics, High-energy phenomena, X-ray binaries and accretion physics, globular clusters Employment Institut de Recherche en Astrophysique et Planétologie, Toulouse, France 2018 CNES Post-doctoral Fellow Pontificia Universidad Católica de Chile, Instituto de Astrofísica 2015 – 2017 FONDECYT Post-doctoral Fellow McGill University, Physics Department 2014 – 2015 Post-doctoral researcher and outreach coordinator Education PhD in astrophysics, McGill University – Vanier Graduate Scholar 2014 Master in physics, McGill University 2009 Bachelor of Science (with distinctions), University of Victoria (BC, Canada) 2007 Euro-American Institute of Technology (EAI Tech, Sophia-Antipolis, France) 2001 – 2003 Note: Two-years preparation program in Astrophysics with courses in French/English, before transferring to UVic Other Research Experience Joint Institute for Laboratory Astrophysics, U. of Colorado (Supervisor: Rosalba Perna) 2013 Research Internship – 2 months, funded by FRQNT International Internship Award). Harvard-Smithsonian Centre for Astrophysics (Supervisor: Alyssa Goodman) 2006 Research Assistant with the COMPLETE team. Sub-mm observations of molecular clouds – 3 months. McGill University, Physics Department (Supervisor: Gil Holder) 2005 Research Assistant. Theoretical Cosmology (weak -
The 2011 Observers Challenge List
TMSP OBSERVER'S CHALLENGE 2011 By Kreig McBride and Tom Masterson All observations must be made at TMSP and 25 out of 30 objects must be viewed to earn a unique TMSP Observer's Award lapel pin. You must create a record of your observations which include date, time, instruments used and a brief description and/or sketch of the object. Your records will be returned to you. Size or ID Number V Magnitude Object Type Constellation RA Dec Description Separation The Sun! View 2 days noting changes. H-alpha, white 1 Sol -28m ½ degree Star Cancer 08h 39' +27d 07' light or projection is OK North Galactic Astronomical Catch this one before it sets. Next to the double star 31 2 N/A N/A Coma Berenices 12h 51' +27d 07' Pole Reference point Comae Berenices Omicron-2 a wide 4.9m, 9m double lies close by as does 3 U Cygni 5.9 – 12.1m N/A Carbon Star Cygnus 19.6h +47d 54' 6” diameter, 12.6m Planetary nebula NGC6884 4 M22 5.1m 7.8' Globular Cluster Sagittarius 18h 36.4' -23d 54' Rich, large and bright 5 NGC 6629 11.3m 15” Planetary Nebula Sagittarius 18h 25.7' -23d 12' Stellar at low powers. Central Star is 12.8m 6 Barnard 86 N/A 5' Dark Nebula Sagittarius 18h 03' -27d 53' “Ink Spot” Imbedded in spectacular star field Faint 1' glow surrounding 9.5m star w/a faint companion 7 NGC 6589-90 N/A 5' x 3' Reflection Nebula Sagittarius 18h 16.9'' -19d 47' 25” to its SW A 3.2m, B Reddish/Orange primary, B white, C is 10m companion 8 ETA Sagittarii 3.6m, C 10m, AB pair 3.6” Quadruple Star Sagittarius 18h 17.6' -36d 46' 93” distant at PA303d and D is 13m star 33” -
The Cosmic Distance Scale • Distance Information Is Often Crucial to Understand the Physics of Astrophysical Objects
The cosmic distance scale • Distance information is often crucial to understand the physics of astrophysical objects. This requires knowing the basic properties of such an object, like its size, its environment, its location in space... • There are essentially two ways to derive distances to astronomical objects, through absolute distance estimators or through relative distance estimators • Absolute distance estimators Objects for whose distance can be measured directly. They have physical properties which allow such a measurement. Examples are pulsating stars, supernovae atmospheres, gravitational lensing time delays from multiple quasar images, etc. • Relative distance estimators These (ultimately) depend on directly measured distances, and are based on the existence of types of objects that share the same intrinsic luminosity (and whose distance has been determined somehow). For example, there are types of stars that have all the same intrinsic luminosity. If the distance to a sample of these objects has been measured directly (e.g. through trigonometric parallax), then we can use these to determine the distance to a nearby galaxy by comparing their apparent brightness to those in the Milky Way. Essentially we use that log(D1/D2) = 1/5 * [(m1 –m2) - (A1 –A2)] where D1 is the distance to system 1, D2 is the distance to system 2, m1 is the apparent magnitudes of stars in S1 and S2 respectively, and A1 and A2 corrects for the absorption towards the sources in S1 and S2. Stars or objects which have the same intrinsic luminosity are known as standard candles. If the distance to such a standard candle has been measured directly, then the relative distances will have been anchored to an absolute distance scale. -
Isolated Elliptical Galaxies and Their Globular Cluster Systems II
A&A 574, A21 (2015) Astronomy DOI: 10.1051/0004-6361/201424530 & c ESO 2015 Astrophysics Isolated elliptical galaxies and their globular cluster systems II. NGC 7796 – globular clusters, dynamics, companion?;?? T. Richtler1;4, R. Salinas2, R. R. Lane1, M. Hilker4, and M. Schirmer3 1 Departamento de Astronomía, Universidad de Concepción, Concepción, Chile e-mail: [email protected] 2 Department of Physics and Astronomy, Michigan State University, 567 Wilson Road, MI 48824 East Lansing, USA 3 Gemini Observatory, Casilla 603, La Serena, Chile 4 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany Received 4 July 2014 / Accepted 16 November 2014 ABSTRACT Context. Rich globular cluster systems, particularly the metal-poor part of them, are thought to be the visible manifestations of long- term accretion processes. The invisible part is the dark matter halo, which may show some correspondence to the globular cluster system. It is therefore interesting to investigate the globular cluster systems of isolated elliptical galaxies, which supposedly have not experienced extended accretion. Aims. We investigate the globular cluster system of the isolated elliptical NGC 7796, present new photometry of the galaxy, and use published kinematical data to constrain the dark matter content. Methods. Deep images in B and R, obtained with the VIsible MultiObject Spectrograph (VIMOS) at the VLT, form the data base. We performed photometry with DAOPHOT and constructed a spherical photometric model. We present isotropic and anisotropic Jeans-models and give a morphological description of the companion dwarf galaxy. Results. The globular cluster system has about 2000 members, so it is not as rich as those of giant ellipticals in galaxy clusters with a comparable stellar mass, but richer than many cluster systems of other isolated ellipticals. -
Globular Clusters
Observing Globular Clusters TAAS Astronomy 101 Jon Schuchardt August 2016 Outline • What are globular clusters? • Historical significance • Shapley-Sawyer classification M5 (Serpens Caput) • How to find, observe, and report on globular clusters What are Globular Star Clusters? • Densely packed, spherical agglomerations of 104 to 107 very old stars (12-14 billion years old) that surround a galactic nucleus • Most in the Milky Way are 10,000 to 50,000 light years away from us • Diameters: 10s to 100s of light years • Densities: average about 1 star per cubic light year, but more dense in the core • About 150 globular clusters known in the Milky Way What are Globular Star Clusters? • Some globular clusters, e.g., M15, have undergone gravitational collapse in their cores • Glob cores can be millions or even billions of times more densely populated than our solar neighborhood • Imagine a night sky with thousands of stars brighter than Sirius! • Black holes of low stellar mass (10-20 solar masses) may be common at the center of globular clusters. They have been detected (2012-2013) in M22 (a pair) and M62 by detecting radio emissions using the Very Large Array M62 (Ophiuchus) Easier to “see” the black holes using radio emissions and the VLA versus a Hubble view of M22 (Sagittarius) J. Strader et al., Nature Oct 4, 2012 Hertzsprung-Russell diagrams: Typical globular cluster (left) and M55 (right) Note the “knee”” H-R Diagram for M3 (Canes Venatici) The “knee” shows where stars begin to depart the Main Sequence on their path to becoming giants Can be used to estimate the age of the cluster “The thing’s hollow -- it goes on forever -- and -- oh my God! -- it’s full of stars!” Commander David Bowman 2001: A Space Odyssey Arthur C. -
Globular Cluster Club
Globular Cluster Observing Club Raleigh Astronomy Club Version 1.2 22 June 2007 Introduction Welcome to the Globular Cluster Observing Club! This list is intended to give you an appreciation for the deep-sky objects known as globular clusters. There are 153 known Milky Way Globular Clusters of which the entire list can be found on the seds.org site listed below. To receive your Gold level we will only have you do sixty of them along with one challenge object from a list of three. Challenge objects being the extra-galactic globular Mayall II (G1) located in the Andromeda Galaxy, Palomar 4 in Ursa Major, and Omega Centauri a magnificent southern globular. The first two challenge your scope and viewing ability while Omega Centauri challenges your ability to plan for a southern view. A Silver level is also available and will be within the range of a 4 inch to 8 inch scope depending upon seeing conditions. Many of the objects are found in the Messier, Caldwell, or Herschel catalogs and can springboard you into those clubs. The list is meant for your viewing enrichment and edification of these types of clusters. It is also meant to enhance your viewing skills. You are encouraged to view the clusters with a critical eye toward the cluster’s size, visual magnitude, resolvability, concentration and colors. The Astronomical League’s Globular Clusters Club book “Guide to the Globular Cluster Observing Club” is an excellent resource for this endeavor. You will be asked to either sketch the cluster or give a short description of your visual impression, citing seeing conditions, time, date, cluster’s size, magnitude, resolvability, concentration, and any star colors. -
High-Velocity Stars in the Cores of Globular Clusters: the Illustrative Case of NGC 2808
A&A 543, A82 (2012) Astronomy DOI: 10.1051/0004-6361/201219062 & c ESO 2012 Astrophysics High-velocity stars in the cores of globular clusters: the illustrative case of NGC 2808 N. Lützgendorf1, A. Gualandris2,3, M. Kissler-Patig1,K.Gebhardt4,H.Baumgardt5, E. Noyola6, J. M. D. Kruijssen2, B. Jalali7,P.T.deZeeuw1,8, and N. Neumayer1 1 European Southern Observatory (ESO), Karl-Schwarzschild-Straße 2, 85748 Garching, Germany e-mail: [email protected] 2 Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Straße 1, 85748 Garching, Germany 3 Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK 4 Astronomy Department, University of Texas at Austin, Austin, TX 78712, USA 5 School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia 6 Instituto de Astronomia, Universidad Nacional Autonoma de Mexico (UNAM), A.P. 70-264, 04510 Mexico, Mexico 7 1. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany 8 Sterrewacht Leiden, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands Received 17 February 2012 / Accepted 15 May 2012 ABSTRACT Context. We report the detection of five high-velocity stars in the core of the globular cluster NGC 2808. The stars lie on the red giant −1 −1 branch and show total velocities between 40 and 45 km s . For a core velocity dispersion σc = 13.4kms , this corresponds to up −1 to 3.4σc. These velocities are close to the estimated escape velocity (∼50 km s ) and suggest an ejection from the core. Two of these stars have been confirmed in our recent integral field spectroscopy data and we will discuss them in more detail here.