DOCSLIB.ORG

A Unified Formation Scenario for the Zoo of Extended Star Clustersand Ultra-Compact Dwarf Galaxies

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Unified Formation Scenario for the Zoo of Extended Star Clustersand Ultra-Compact Dwarf Galaxies A UNIFIED FORMATION SCENARIO FOR THE ZOO OF EXTENDED STAR CLUSTERS AND ULTRA-COMPACT DWARF GALAXIES DISSERTATION zur Erlangung des Doktorgrades (Dr. rer. nat.) der Mathematisch-Naturwissenschaftlichen Fakultät der Rheinischen Friedrich-Wilhelms-Universität Bonn vorgelegt von RENATE CLAUDIA BRÜNS aus Bonn Bonn, 2013 Angefertigt mit Genehmigung der Mathematisch-Naturwissenschaftlichen Fakultät der Rheinischen Friedrich-Wilhelms-Universität Bonn 1. Gutachter: Prof. Dr. P. Kroupa 2. Gutachter: Prof. Dr. U. Klein Tag der Promotion: 16. Juni 2014 Erscheinungsjahr: 2014 Contents Abstract 1 1 Introduction 3 1.1 Old Star Clusters in the Local Group ......................... 3 1.2 Old Star Clusters beyond the Local Group ..................... 7 1.3 Ultra-Compact Dwarf Galaxies ............................ 8 1.4 Young Massive Star Clusters and Star Cluster Complexes ............. 9 1.5 Outline of Thesis .................................... 14 2 NumericalMethod 17 2.1 N-BodyCodes ..................................... 17 2.1.1 Set-Up of the Initial Conditions ....................... 18 2.1.2 The Integrator ................................. 22 2.1.3 Determination of Accelerations from the N Particles ............ 23 2.1.4 The Analytical External Tidal Field ..................... 26 2.1.5 Determination of the Enclosed Mass and the Effective Radius ...... 29 2.2 The Particle-Mesh Code SUPERBOX ......................... 29 2.2.1 Definition of the Grids and the Determination of Accelerations ...... 30 2.2.2 Illustration of the Combination of the Grid Potentials ........... 32 2.2.3 General Framework for the Choice of Parameters for the Simulations . 34 2.2.4 SUPERBOX++ versus Fortran SUPERBOX ................... 40 3 ACatalogofECsandUCDsinVariousEnvironments 43 3.1 Introduction ...................................... 43 3.2 The Observational Basis of the EO Catalog ..................... 44 3.2.1 EOs in Late-Type Galaxies .......................... 44 3.2.2 EOs in Early-Type Galaxies .......................... 44 3.3 Results ......................................... 45 3.3.1 Trends and Correlations of the EO Parameters ............... 45 3.3.2 Correlation of EO Parameters with those of their Host Galaxies. ..... 48 3.4 Discussion ....................................... 49 3.4.1 Distribution in the Effective Radius Versus Total Luminosity Space ... 49 3.4.2 EO Luminosity Functions ........................... 55 3.4.3 Spatial Distribution of EOs .......................... 60 3.5 Summary & Conclusions ............................... 63 I II CONTENTS 4 AnApplicationoftheFormationScenarioonSpecificEOs 65 4.1 Introduction ...................................... 65 4.2 Faint Fuzzy Star Clusters in NGC 1023 ....................... 66 4.2.1 Introduction .................................. 66 4.2.2 Set-up of the Numericial Simulations and Varied Parameters ....... 67 4.2.3 Results ..................................... 69 4.2.4 Discussion and Conclusions ......................... 74 4.3 The Milky Way EO NGC 2419 ............................ 78 4.3.1 Introduction .................................. 78 4.3.2 Set-Up and Varied Parameters ........................ 79 4.3.3 Results ..................................... 84 4.3.4 Discussion ................................... 93 4.3.5 Summary .................................... 96 4.4 Conclusions ...................................... 97 5 AGeneralStudyontheFormationofECsandUCDs 99 5.1 Introduction and General Set-Up ........................... 99 5.2 The Effect of the Initial CC Parameters Mass and Size ............... 102 5.2.1 Numerical Set-Up and Varied Parameters .................. 102 5.2.2 Results ..................................... 103 5.2.3 Comparison with Observations ....................... 111 5.3 The Influence of the Orbit on the Evolution of Merger Objects .......... 112 5.3.1 Numerical Set-Up and Varied Parameters .................. 112 5.3.2 Results from the Circular Orbits ....................... 113 5.3.3 Results from the Eccentric Orbits ...................... 120 5.3.4 Comparison with Observations ....................... 124 5.4 The Formation of Extremely Extended Clusters ................... 125 5.4.1 Numerical Set-Up and Varied Parameters .................. 126 5.4.2 Results ..................................... 126 5.4.3 Comparison with Observations ....................... 128 5.5 Discussion ....................................... 129 5.5.1 The Merging Star Cluster vs. the Galaxy Threshing Scenario ....... 129 5.5.2 The Gilmore Gap ............................... 132 5.6 Conclusion ....................................... 135 6 Summary 137 6.1 A Comprehensive Catalog of Observed EOs .................... 138 6.2 The Application of the Formation Scenario to Specific EOs ............ 138 6.2.1 Faint Fuzzy Star Clusters in NGC 1023 ................... 138 6.2.2 The Milky Way Cluster NGC 2419 ...................... 139 6.3 A General Study on the Formation of EOs ...................... 140 6.3.1 A Parameter Study of the Initial CC Parameters Mass and Size ...... 140 6.3.2 A Parameter Study of the Dependence on the Orbit ............ 140 6.3.3 A Parameter Study on the Formation of Extremely Extended EOs .... 141 6.4 Conclusion ....................................... 141 7 Outlook 143 7.1 Observational Constraints on the Initial CCs .................... 143 7.2 Computational Refinements of the Merging Star Cluster Scenario ........ 144 7.3 Computational Projects for the Galaxy Threshing Scenario ............ 146 CONTENTS III 7.4 Observational Requirements on EOs ......................... 146 A Catalog of Extended Stellar Dynamical Objects 149 B AManualforMergingStarClusterSimulations 169 B.1 Setup of a Cluster Complex on an Orbit Around a Galaxy ............. 169 B.1.1 Creation of a Star Cluster ........................... 169 B.1.2 Generation of a Cluster Complex Model .................. 173 B.1.3 Concatenation of the CC Distribution, the Individual SCs, and the Orbit 173 B.2 Running the Simulations ............................... 174 B.2.1 Determination of Merged Star Clusters ................... 176 C Summary Tables of the Simulation Results 181 C.1 Results of the Study of Faint Fuzzies in NGC 1023 ................. 182 C.2 Results of the Study of the Milky Way EO NGC 2419 ................ 183 C.3 Nomenclature of the Simulations of the General EO Study ............ 184 C.4 Results of the Study with Varied Initial CC Parameters Mass and Size ...... 185 C.5 Results of the Study with Varied Orbital Parameters ................ 187 C.6 Results of the Study on the Formation of Extremely Extended EOs ........ 188 Bibliography 189 Acknowledgements 199 IV CONTENTS List of Figures 1.1 Effective radii vs. distances of GCs/ECs of the Milky Way and its companions . 4 1.2 Effective radii vs. luminosities of GCs/ECs of the Milky Way and its companions 5 1.3 The Antennae galaxies and the exemplary CC knot S ............... 10 1.4 The Whirlpool galaxy and an exemplary CC in the galactic disk ......... 12 1.5 The Tadpole galaxy and an exemplary CC in the tidal tail ............. 13 2.1 Basic structure of an N-body code .......................... 18 2.2 Illustration of the leapfrog integrator ........................ 22 2.3 Geometry of the determination of the effective potential .............. 27 2.4 Illustration of the impact of the mass and size of a CC on its tidal radius ..... 28 2.5 Determination of the enclosed mass and effective radius of a merger object ... 29 2.6 Illustration of the three different grids used in SUPERBOX ............. 31 2.7 Illustration of the different combinations of the grid potentials .......... 31 2.8 Example of the determination of the total potential ................. 33 2.9 Illustration of the setup of the merging star cluster simulations .......... 35 2.10 Surface density profile of a merger object for different grid resolutions ...... 36 2.11 Surface density profile of a merger object for different numbers of particles ... 38 2.12 Illustration of the merging criterion ......................... 39 2.13 Comparison of results from SUPERBOX and SUPERBOX++ ............. 41 3.1 Effective radii of EOs versus their total V-band luminosities ............ 45 3.2 Effective radii and total luminosities of EOs vs. their projected distances .... 46 3.3 Histogram of the number of EOs at different total V-band luminosities ..... 47 3.4 Histogram of the number of EOs at different effective radii ............ 47 3.5 Histogram of the number of EOs at different projected radii ............ 47 3.6 EO parameters vs. the total V-band luminosity of their host galaxy ........ 49 3.7 EO parameters vs. distance of their host galaxy to the Galaxy ........... 50 3.8 EO parameters and trends of equal mean surface brightness ........... 51 3.9 Overview of confirmed and candidate EOs ..................... 52 3.10 Observed parameters of GCs, EOs, and early-type galaxies ............ 53 3.11 Histogram of the effective radii of all GCs and EOs ................ 54 3.12 Luminosity function of EOs in late-type galaxies .................. 55 3.13 Luminosity function of EOs in NGC 4365 ...................... 56 3.14 Luminosity function of EOs in early-type galaxies ................. 57 3.15 Luminosity function of EOs in early-type galaxies w/o NGC 4365 and NGC 1275 57 3.16 Turnover of the luminosity function as a function of the effective radius ..... 59 3.17 Overview of the distribution of EOs in M51 ..................... 61 3.18 Spectroscopically confirmed star clusters of the Hydra Cluster .......... 62 V VI LIST OF
Load more

Recommended publications
  • Messier Objects
    Messier Objects From the Stocker Astroscience Center at Florida International University Miami Florida The Messier Project Main contributors: • Daniel Puentes • Steven Revesz • Bobby Martinez Charles Messier • Gabriel Salazar • Riya Gandhi • Dr. James Webb – Director, Stocker Astroscience center • All images reduced and combined using MIRA image processing software. (Mirametrics) What are Messier Objects? • Messier objects are a list of astronomical sources compiled by Charles Messier, an 18th and early 19th century astronomer. He created a list of distracting objects to avoid while comet hunting. This list now contains over 110 objects, many of which are the most famous astronomical bodies known. The list contains planetary nebula, star clusters, and other galaxies. - Bobby Martinez The Telescope The telescope used to take these images is an Astronomical Consultants and Equipment (ACE) 24- inch (0.61-meter) Ritchey-Chretien reflecting telescope. It has a focal ratio of F6.2 and is supported on a structure independent of the building that houses it. It is equipped with a Finger Lakes 1kx1k CCD camera cooled to -30o C at the Cassegrain focus. It is equipped with dual filter wheels, the first containing UBVRI scientific filters and the second RGBL color filters. Messier 1 Found 6,500 light years away in the constellation of Taurus, the Crab Nebula (known as M1) is a supernova remnant. The original supernova that formed the crab nebula was observed by Chinese, Japanese and Arab astronomers in 1054 AD as an incredibly bright “Guest star” which was visible for over twenty-two months. The supernova that produced the Crab Nebula is thought to have been an evolved star roughly ten times more massive than the Sun.
    [Show full text]
  • THE 1000 BRIGHTEST HIPASS GALAXIES: H I PROPERTIES B
    The Astronomical Journal, 128:16–46, 2004 July A # 2004. The American Astronomical Society. All rights reserved. Printed in U.S.A. THE 1000 BRIGHTEST HIPASS GALAXIES: H i PROPERTIES B. S. Koribalski,1 L. Staveley-Smith,1 V. A. Kilborn,1, 2 S. D. Ryder,3 R. C. Kraan-Korteweg,4 E. V. Ryan-Weber,1, 5 R. D. Ekers,1 H. Jerjen,6 P. A. Henning,7 M. E. Putman,8 M. A. Zwaan,5, 9 W. J. G. de Blok,1,10 M. R. Calabretta,1 M. J. Disney,10 R. F. Minchin,10 R. Bhathal,11 P. J. Boyce,10 M. J. Drinkwater,12 K. C. Freeman,6 B. K. Gibson,2 A. J. Green,13 R. F. Haynes,1 S. Juraszek,13 M. J. Kesteven,1 P. M. Knezek,14 S. Mader,1 M. Marquarding,1 M. Meyer,5 J. R. Mould,15 T. Oosterloo,16 J. O’Brien,1,6 R. M. Price,7 E. M. Sadler,13 A. Schro¨der,17 I. M. Stewart,17 F. Stootman,11 M. Waugh,1, 5 B. E. Warren,1, 6 R. L. Webster,5 and A. E. Wright1 Received 2002 October 30; accepted 2004 April 7 ABSTRACT We present the HIPASS Bright Galaxy Catalog (BGC), which contains the 1000 H i brightest galaxies in the southern sky as obtained from the H i Parkes All-Sky Survey (HIPASS). The selection of the brightest sources is basedontheirHi peak flux density (Speak k116 mJy) as measured from the spatially integrated HIPASS spectrum. 7 ; 10 The derived H i masses range from 10 to 4 10 M .
    [Show full text]
  • Giant H II Regions in the Merging System NGC 3256: Are They the Birthplaces of Globular Clusters?
    CORE Metadata, citation and similar papers at core.ac.uk Provided by CERN Document Server Paper I: To be submitted to A.J. Giant H II regions in the merging system NGC 3256: Are they the birthplaces of globular clusters? J. English University of Manitoba K.C. Freeman Research School of Astronomy and Astrophysics, The Australian National University ABSTRACT CCD images and spectra of ionized hydrogen in the merging system NGC3256 were acquired as part of a kinematic study to investigate the formation of globular clusters (GC) during the interactions and mergers of disk galaxies. This paper focuses on the proposition by Kennicutt & Chu (1988) that giant H II regions, with an Hα luminosity > 1:5 1040 erg s 1, are birthplaces of young populous clusters (YPC’s ). × − Although NGC 3256 has relatively few (7) giant H II complexes, compared to some other interacting systems, these regions are comparable in total flux to about 85 30- Doradus-like H II regions (30-Dor GHR’s). The bluest, massive YPC’s (Zepf et al. 1999) are located in the vicinity of observed 30-Dor GHR’s, contributing to the notion that some fraction of 30-Dor GHR’s do cradle massive YPC’s, as 30 Dor harbors R136. If interactions induce the formation of 30-Dor GHR’s, the observed luminosities indi- cate that almost 900 30-Dor GHR’s would form in NGC 3256 throughout its merger epoch. In order for 30-Dor GHR’s to be considered GC progenitors, this number must be consistent with the specific frequencies of globular clusters estimated for elliptical galaxies formed via mergers of spirals (Ashman & Zepf 1993).
    [Show full text]
  • The Large Scale Universe As a Quasi Quantum White Hole
    International Astronomy and Astrophysics Research Journal 3(1): 22-42, 2021; Article no.IAARJ.66092 The Large Scale Universe as a Quasi Quantum White Hole U. V. S. Seshavatharam1*, Eugene Terry Tatum2 and S. Lakshminarayana3 1Honorary Faculty, I-SERVE, Survey no-42, Hitech city, Hyderabad-84,Telangana, India. 2760 Campbell Ln. Ste 106 #161, Bowling Green, KY, USA. 3Department of Nuclear Physics, Andhra University, Visakhapatnam-03, AP, India. Authors’ contributions This work was carried out in collaboration among all authors. Author UVSS designed the study, performed the statistical analysis, wrote the protocol, and wrote the first draft of the manuscript. Authors ETT and SL managed the analyses of the study. All authors read and approved the final manuscript. Article Information Editor(s): (1) Dr. David Garrison, University of Houston-Clear Lake, USA. (2) Professor. Hadia Hassan Selim, National Research Institute of Astronomy and Geophysics, Egypt. Reviewers: (1) Abhishek Kumar Singh, Magadh University, India. (2) Mohsen Lutephy, Azad Islamic university (IAU), Iran. (3) Sie Long Kek, Universiti Tun Hussein Onn Malaysia, Malaysia. (4) N.V.Krishna Prasad, GITAM University, India. (5) Maryam Roushan, University of Mazandaran, Iran. Complete Peer review History: http://www.sdiarticle4.com/review-history/66092 Received 17 January 2021 Original Research Article Accepted 23 March 2021 Published 01 April 2021 ABSTRACT We emphasize the point that, standard model of cosmology is basically a model of classical general relativity and it seems inevitable to have a revision with reference to quantum model of cosmology. Utmost important point to be noted is that, ‘Spin’ is a basic property of quantum mechanics and ‘rotation’ is a very common experience.
    [Show full text]
  • Guide Du Ciel Profond
    Guide du ciel profond Olivier PETIT 8 mai 2004 2 Introduction hjjdfhgf ghjfghfd fg hdfjgdf gfdhfdk dfkgfd fghfkg fdkg fhdkg fkg kfghfhk Table des mati`eres I Objets par constellation 21 1 Androm`ede (And) Andromeda 23 1.1 Messier 31 (La grande Galaxie d'Androm`ede) . 25 1.2 Messier 32 . 27 1.3 Messier 110 . 29 1.4 NGC 404 . 31 1.5 NGC 752 . 33 1.6 NGC 891 . 35 1.7 NGC 7640 . 37 1.8 NGC 7662 (La boule de neige bleue) . 39 2 La Machine pneumatique (Ant) Antlia 41 2.1 NGC 2997 . 43 3 le Verseau (Aqr) Aquarius 45 3.1 Messier 2 . 47 3.2 Messier 72 . 49 3.3 Messier 73 . 51 3.4 NGC 7009 (La n¶ebuleuse Saturne) . 53 3.5 NGC 7293 (La n¶ebuleuse de l'h¶elice) . 56 3.6 NGC 7492 . 58 3.7 NGC 7606 . 60 3.8 Cederblad 211 (N¶ebuleuse de R Aquarii) . 62 4 l'Aigle (Aql) Aquila 63 4.1 NGC 6709 . 65 4.2 NGC 6741 . 67 4.3 NGC 6751 (La n¶ebuleuse de l’œil flou) . 69 4.4 NGC 6760 . 71 4.5 NGC 6781 (Le nid de l'Aigle ) . 73 TABLE DES MATIERES` 5 4.6 NGC 6790 . 75 4.7 NGC 6804 . 77 4.8 Barnard 142-143 (La tani`ere noire) . 79 5 le B¶elier (Ari) Aries 81 5.1 NGC 772 . 83 6 le Cocher (Aur) Auriga 85 6.1 Messier 36 . 87 6.2 Messier 37 . 89 6.3 Messier 38 .
    [Show full text]
  • Modeling and Interpretation of the Ultraviolet Spectral Energy Distributions of Primeval Galaxies
    Ecole´ Doctorale d'Astronomie et Astrophysique d'^Ile-de-France UNIVERSITE´ PARIS VI - PIERRE & MARIE CURIE DOCTORATE THESIS to obtain the title of Doctor of the University of Pierre & Marie Curie in Astrophysics Presented by Alba Vidal Garc´ıa Modeling and interpretation of the ultraviolet spectral energy distributions of primeval galaxies Thesis Advisor: St´ephane Charlot prepared at Institut d'Astrophysique de Paris, CNRS (UMR 7095), Universit´ePierre & Marie Curie (Paris VI) with financial support from the European Research Council grant `ERC NEOGAL' Composition of the jury Reviewers: Alessandro Bressan - SISSA, Trieste, Italy Rosa Gonzalez´ Delgado - IAA (CSIC), Granada, Spain Advisor: St´ephane Charlot - IAP, Paris, France President: Patrick Boisse´ - IAP, Paris, France Examinators: Jeremy Blaizot - CRAL, Observatoire de Lyon, France Vianney Lebouteiller - CEA, Saclay, France Dedicatoria v Contents Abstract vii R´esum´e ix 1 Introduction 3 1.1 Historical context . .4 1.2 Early epochs of the Universe . .5 1.3 Galaxytypes ......................................6 1.4 Components of a Galaxy . .8 1.4.1 Classification of stars . .9 1.4.2 The ISM: components and phases . .9 1.4.3 Physical processes in the ISM . 12 1.5 Chemical content of a galaxy . 17 1.6 Galaxy spectral energy distributions . 17 1.7 Future observing facilities . 19 1.8 Outline ......................................... 20 2 Modeling spectral energy distributions of galaxies 23 2.1 Stellar emission . 24 2.1.1 Stellar population synthesis codes . 24 2.1.2 Evolutionary tracks . 25 2.1.3 IMF . 29 2.1.4 Stellar spectral libraries . 30 2.2 Absorption and emission in the ISM . 31 2.2.1 Photoionization code: CLOUDY .......................
    [Show full text]
  • Arxiv:1704.01678V2 [Astro-Ph.GA] 28 Jul 2017 Been Notoriously Difficult, Resulting Mostly in Upper Lim- Highest Escape Fractions Measured to Date Among Low- Its (E.G
    Submitted: 3 March 2017 Preprint typeset using LATEX style AASTeX6 v. 1.0 MRK 71 / NGC 2366: THE NEAREST GREEN PEA ANALOG Genoveva Micheva1, M. S. Oey1, Anne E. Jaskot2, and Bethan L. James3 (Accepted 24 July 2017) 1University of Michigan, 311 West Hall, 1085 S. University Ave, Ann Arbor, MI 48109-1107, USA 2Department of Astronomy, Smith College, Northampton, MA 01063, USA 3STScI, 3700 San Martin Drive, Baltimore, MD 21218, USA ABSTRACT We present the remarkable discovery that the dwarf irregular galaxy NGC 2366 is an excellent analog of the Green Pea (GP) galaxies, which are characterized by extremely high ionization parameters. The similarities are driven predominantly by the giant H II region Markarian 71 (Mrk 71). We compare the system with GPs in terms of morphology, excitation properties, specific star-formation rate, kinematics, absorption of low-ionization species, reddening, and chemical abundance, and find consistencies throughout. Since extreme GPs are associated with both candidate and confirmed Lyman continuum (LyC) emitters, Mrk 71/NGC 2366 is thus also a good candidate for LyC escape. The spatially resolved data for this object show a superbubble blowout generated by mechanical feedback from one of its two super star clusters (SSCs), Knot B, while the extreme ionization properties are driven by the . 1 Myr-old, enshrouded SSC Knot A, which has ∼ 10 times higher ionizing luminosity. Very massive stars (> 100 M ) may be present in this remarkable object. Ionization-parameter mapping indicates the blowout region is optically thin in the LyC, and the general properties also suggest LyC escape in the line of sight.
    [Show full text]
  • Spiral Galaxies, Elliptical Galaxies, Irregular Galaxies, Dwarf Galaxies, Peculiar/Interacting Galalxies Spiral Galaxies
    Lecture 33: Announcements 1) Pick up graded hwk 5. Good job: Jessica, Jessica, and Elizabeth for a 100% score on hwk 5 and the other 25% of the class with an A. 2) Article and homework 7 were posted on class website on Monday (Apr 18) . Due on Mon Apr 25. 3) Reading Assignment for Quiz Wed Apr 27 Ch 23, Cosmic Perspectives: The Beginning of Time 4) Exam moved to Wed May 4 Lecture 33: Galaxy Formation and Evolution Several topics for galaxy evolution have already been covered in Lectures 2, 3, 4,14,15,16. you should refer to your in-class notes for these topics which include: - Types of galaxies (barred spiral, unbarred spirals, ellipticals, irregulars) - The Local Group of Galaxies, The Virgo and Coma Cluster of galaxies - How images of distant galaxies allow us to look back in time - The Hubble Ultra Deep Field (HUDF) - The Doppler blueshift (Lectures 15-16) - Tracing stars, dust, gas via observations at different wavelengths (Lecture15-16). In next lectures, we will cover - Galaxy Classification. The Hubble Sequence - Mapping the Distance of Galaxies - Mapping the Visible Constituents of Galaxies: Stars, Gas, Dust - Understanding Galaxy Formation and Evolution - Galaxy Interactions: Nearby Galaxies, the Milky Way, Distant Galaxies - Mapping the Dark Matter in Galaxies and in the Universe - The Big Bang - Fates of our Universe and Dark Energy Galaxy Classification Galaxy: Collection of few times (108 to 1012) stars orbiting a common center and bound by gravity. Made of gas, stars, dust, dark matter. There are many types of galaxies and they can be classfiied according to different criteria.
    [Show full text]
  • And Ecclesiastical Cosmology
    GSJ: VOLUME 6, ISSUE 3, MARCH 2018 101 GSJ: Volume 6, Issue 3, March 2018, Online: ISSN 2320-9186 www.globalscientificjournal.com DEMOLITION HUBBLE'S LAW, BIG BANG THE BASIS OF "MODERN" AND ECCLESIASTICAL COSMOLOGY Author: Weitter Duckss (Slavko Sedic) Zadar Croatia Pусскй Croatian „If two objects are represented by ball bearings and space-time by the stretching of a rubber sheet, the Doppler effect is caused by the rolling of ball bearings over the rubber sheet in order to achieve a particular motion. A cosmological red shift occurs when ball bearings get stuck on the sheet, which is stretched.“ Wikipedia OK, let's check that on our local group of galaxies (the table from my article „Where did the blue spectral shift inside the universe come from?“) galaxies, local groups Redshift km/s Blueshift km/s Sextans B (4.44 ± 0.23 Mly) 300 ± 0 Sextans A 324 ± 2 NGC 3109 403 ± 1 Tucana Dwarf 130 ± ? Leo I 285 ± 2 NGC 6822 -57 ± 2 Andromeda Galaxy -301 ± 1 Leo II (about 690,000 ly) 79 ± 1 Phoenix Dwarf 60 ± 30 SagDIG -79 ± 1 Aquarius Dwarf -141 ± 2 Wolf–Lundmark–Melotte -122 ± 2 Pisces Dwarf -287 ± 0 Antlia Dwarf 362 ± 0 Leo A 0.000067 (z) Pegasus Dwarf Spheroidal -354 ± 3 IC 10 -348 ± 1 NGC 185 -202 ± 3 Canes Venatici I ~ 31 GSJ© 2018 www.globalscientificjournal.com GSJ: VOLUME 6, ISSUE 3, MARCH 2018 102 Andromeda III -351 ± 9 Andromeda II -188 ± 3 Triangulum Galaxy -179 ± 3 Messier 110 -241 ± 3 NGC 147 (2.53 ± 0.11 Mly) -193 ± 3 Small Magellanic Cloud 0.000527 Large Magellanic Cloud - - M32 -200 ± 6 NGC 205 -241 ± 3 IC 1613 -234 ± 1 Carina Dwarf 230 ± 60 Sextans Dwarf 224 ± 2 Ursa Minor Dwarf (200 ± 30 kly) -247 ± 1 Draco Dwarf -292 ± 21 Cassiopeia Dwarf -307 ± 2 Ursa Major II Dwarf - 116 Leo IV 130 Leo V ( 585 kly) 173 Leo T -60 Bootes II -120 Pegasus Dwarf -183 ± 0 Sculptor Dwarf 110 ± 1 Etc.
    [Show full text]
  • The Milky Way Galaxy Contents Summary
    UNESCO EOLSS ENCYCLOPEDIA The Milky Way galaxy James Binney Physics Department Oxford University Key Words: Milky Way, galaxies Contents Summary • Introduction • Recognition of the size of the Milky Way • The Centre • The bulge-bar • History of the bulge Globular clusters • Satellites • The disc • Spiral structure Interstellar gas Moving groups, associations and star clusters The thick disc Local mass density The dark halo • Summary Our Galaxy is typical of the galaxies that dominate star formation in the present Universe. It is a barred spiral galaxy – a still-forming disc surrounds an old and barred spheroid. A massive black hole marks the centre of the Galaxy. The Sun sits far out in the disc and in visible light our view of the Galaxy is limited by interstellar dust. Consequently, the large-scale structure of the Galaxy must be inferred from observations made at infrared and radio wavelengths. The central bar and spiral structure in the stellar disc generate significant non-axisymmetric gravitational forces that make the gas disc and its embedded star formation strongly non-axisymmetric. Molecular hydrogen is more centrally concentrated than atomic hydrogen and much of it is contained in molecular clouds within which stars form. Probably all stars are formed in an association or cluster, and energy released by the more massive stars quickly disperses gas left over from their birth. This dispersal of residual gas usually leads to the dissolution of the association or cluster. The stellar disc can be decomposed to a thin disc, which comprises stars formed over most of the Galaxy’s lifetime, and a thick disc, which contains only stars formed in about the Galaxy’s first gigayear.
    [Show full text]
  • Revisiting the Low-Luminosity Galaxy Population of the NGC 5846 Group with SDSS
    A&A 511, A12 (2010) Astronomy DOI: 10.1051/0004-6361/200811013 & c ESO 2010 Astrophysics Revisiting the low-luminosity galaxy population of the NGC 5846 group with SDSS P. Eigenthaler and W. W. Zeilinger Institut für Astronomie, Universität Wien, Türkenschanzstraße 17, 1180 Vienna, Austria e-mail: [email protected] Received 22 September 2008 / Accepted 26 November 2009 ABSTRACT Context. Low-luminosity galaxies are known to outnumber the bright galaxy population in poor groups and clusters of galaxies. Yet, the investigation of low-luminosity galaxy populations outside the Local Group remains rare and the dependence on different group environments is still poorly understood. Previous investigations have uncovered the photometric scaling relations of early-type dwarfs and a strong dependence of morphology with environment. Aims. The present study aims to analyse the photometric and spectroscopic properties of the low-luminosity galaxy population in the nearby, well-evolved and early-type dominated NGC 5846 group of galaxies. It is the third most massive aggregate of early-type galaxies after the Virgo and Fornax clusters in the local universe. Photometric scaling relations and the distribution of morphological types as well as the characteristics of emission-line galaxies are investigated. Methods. Spectroscopically selected low-luminosity group members from the Sloan Digital Sky Survey with cz < 3000 km s−1 within aradiusof2◦ = 0.91 Mpc around NGC 5846 are analysed. Surface brightness profiles of early-type galaxies are fit by a Sérsic model ∝r1/n. Star formation rates, oxygen abundances, and emission characteristics are determined for emission-line galaxies. Results. Seven new group members showing no entry in previous catalogues are identified in the outer (>1.33◦) parts of the system.
    [Show full text]
  • Monthly Newsletter of the Durban Centre - March 2018
    Page 1 Monthly Newsletter of the Durban Centre - March 2018 Page 2 Table of Contents Chairman’s Chatter …...…………………….……….………..….…… 3 Andrew Gray …………………………………………...………………. 5 The Hyades Star Cluster …...………………………….…….……….. 6 At the Eye Piece …………………………………………….….…….... 9 The Cover Image - Antennae Nebula …….……………………….. 11 Galaxy - Part 2 ….………………………………..………………….... 13 Self-Taught Astronomer …………………………………..………… 21 The Month Ahead …..…………………...….…….……………..…… 24 Minutes of the Previous Meeting …………………………….……. 25 Public Viewing Roster …………………………….……….…..……. 26 Pre-loved Telescope Equipment …………………………...……… 28 ASSA Symposium 2018 ………………………...……….…......…… 29 Member Submissions Disclaimer: The views expressed in ‘nDaba are solely those of the writer and are not necessarily the views of the Durban Centre, nor the Editor. All images and content is the work of the respective copyright owner Page 3 Chairman’s Chatter By Mike Hadlow Dear Members, The third month of the year is upon us and already the viewing conditions have been more favourable over the last few nights. Let’s hope it continues and we have clear skies and good viewing for the next five or six months. Our February meeting was well attended, with our main speaker being Dr Matt Hilton from the Astrophysics and Cosmology Research Unit at UKZN who gave us an excellent presentation on gravity waves. We really have to be thankful to Dr Hilton from ACRU UKZN for giving us his time to give us presentations and hope that we can maintain our relationship with ACRU and that we can draw other speakers from his colleagues and other research students! Thanks must also go to Debbie Abel and Piet Strauss for their monthly presentations on NASA and the sky for the following month, respectively.
    [Show full text]