DOCSLIB.ORG

The Globular Cluster System of NGC 4526

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Globular Cluster System of NGC 4526 The globular cluster system of NGC 4526 Leonie Chevalier Presented in fulfillment of the requirements of the degree of Masters by Research { Faculty of Science and Technology Swinburne University i You couldn't put off the inevitable. Because sooner or later, you reached the place when the inevitable just went and waited - Terry Pratchett, Small Gods ii Abstract With ages up to ∼ 12.8 Gyr, globular clusters (GCs) are some of the oldest objects we observe in galaxies and are thought to preserve their parent galaxy's chemo-dynamical properties at the time of their formation. A single galaxy can have tens of thousands of GCs associated with it. Globular cluster systems have long been thought to be a useful tool for constraining galaxy formation scenarios and even to infer a galaxy's individual formation history. More recently GCs have been used to infer dark matter masses of galaxies. This thesis focuses on the GC system of the lenticular galaxy NGC 4526. We used Subaru imaging to study the system's full extent and infer the total number of GCs as well as the substructure in the GC system. Additionally we used the DEIMOS spectrograph on the Keck telescope to obtain radial velocities for 106 GCs to be used in studying the dark matter content of NGC 4526. The combination of multiband photometric data in combination with the spectroscopic data gained by DEIMOS is a significant improvement on existing data sets that only partially imaged the GC system. To put our findings into a broader context we compared NGC 4526 to the results of 26 other elliptical and lenticular galaxies (and their GC systems) from existing literature. Additionally we investigated the dark matter content of NGC 4526 and how this measurement is dependent on sample selection and model assumptions. We found that this galaxy has an unusually high fraction (80%) of metal-poor GCs and a high dark matter fraction for its mass. In fact it was one of the highest metal poor fractions observed in our sample of 27 galaxies. However, it is still consistent with the general trend we derived from our full sample of galaxies. The GC system itself did not appear overly extended. We propose that this particular galaxy most likely formed through a series of minor mergers. iii iv Acknowledgements I would like to thank the people who have supported me throughout writing this thesis. To Vincent for his love and support throughout, to Manodeep and Ned for the best coding help and high fives and most of all to Caitlin without whom this thesis would never have been finished. v vi Declaration The work presented in this thesis has been carried out in the Centre for Astrophysics & Supercomputing at Swinburne University of Technology between 2016 and 2018. This thesis contains no material that has been accepted for the award of any other degree or diploma. To the best of my knowledge, this thesis contains no material previously published or written by another author, except where due reference is made in the text of the thesis. Leonie Chevalier Melbourne, Victoria, Australia 2018 vii Contents Abstract ii Acknowledgements iii Declaration v List of Figures x List of Tables xi 1 Introduction 1 1.1 Individual globular clusters . 1 1.2 Globular cluster systems . 2 1.3 Globular cluster systems and their host Galaxies . 3 1.4 Large scale studies of globular cluster systems . 5 1.4.1 ACS Virgo and Fornax Cluster Survey . 5 1.4.2 Next Generation Virgo Cluster survey . 5 1.4.3 SLUGGS . 6 1.5 The globular cluster system - dark matter connection . 8 1.6 The lenticular galaxy NGC 4526 . 8 2 Simulations 11 2.1 Simulations of globular cluster system formation and evolution . 11 2.1.1 Globular cluster systems in galaxy formation models . 11 2.1.2 Globular clusters in cosmological simulations . 14 3 Observations 21 3.1 Data Collection and Reduction . 21 4 Photometry 23 4.1 Galaxy light model . 23 4.2 Object detection . 24 4.3 Zeropoint estimates and final magnitudes . 24 ix x Contents 4.4 Globular cluster candidate selection . 25 4.5 Globular cluster colour distribution . 31 4.6 HST sources . 32 4.7 Completeness . 33 5 Analysis 37 5.1 Radial colour gradients . 37 5.2 Surface density profiles . 38 6 Global relations of GC systems 43 6.1 Radial extent of GC system . 43 6.2 Mass and dark matter fraction . 44 6.3 Specific frequency . 49 7 Discussion 53 8 Conclusion and proposed further work 59 8.1 Proposed further work . 60 Bibliography 70 A Appendix A 71 List of Figures 4.1 Colour-magnitude diagram . 26 4.2 Colour-colour diagram . 27 4.3 CLASS STAR selection . 29 4.4 GC candidate positions . 30 4.5 Histogram of GC candidates . 32 4.6 Completeness tests . 34 5.1 Colour Gradient . 38 5.2 Surface density profiles . 40 6.1 Comparison of NGC 4526 to other lenticular and elliptical galaxies . 45 6.2 Comparison of GCs extent to Host galaxy properties . 46 6.3 Radial velocities of NGC 4526 GCs . 48 6.4 Dark matter fraction scaling relation . 50 xi List of Tables 4.1 GMM results . 33 5.1 Sersic fits . 41 6.1 Dark matter fractions . 51 A.1 Full candidate list . 71 xiii 1 Introduction 1.1 Individual globular clusters Globular clusters (GC) are gravitationally bound clusters of ∼ 104 - 106 stars situated in and around galaxies. They are spherical with an average half light radius of 3pc (Masters 4 −3 et al., 2010) and have an average core density of ∼ 8×10 M pc Portegies Zwart et al. (2010). With ages up to ∼ 12:8 Gyr (Forbes et al., 2015) globular clusters are among the oldest objects we observe in galaxies. For a long time astronomers believed that all stars within a globular cluster formed at the same time and therefore are an example of a simple stellar population. This would imply that they have the potential to preserve their parent galaxy's chemo-dynamical properties at the time of their formation, and therefore they make an ideal tracer for galaxy formation and evolution. Conditions that promote the formation of globular clusters are gas rich, high density and high temperature, which makes galaxies with gas-rich clumpy discs or those that are undergoing major mergers almost ideal for GCs formation. It has also been proposed that GCs may form within their own low-mass dark matter (DM) halos (Kimm et al., 2016). Initial issues with this model have been that current observations show no evidence of DM halos associated with GCs (Conroy et al., 2011). Furthermore, based on our current understanding of cosmology and star formation, had GCs indeed formed in a DM halo that was subsequently stripped, we would expect to see a range of stellar populations within the GCs due to the continuous accretion of gas onto the DM halo. 1 2 Chapter 1. Introduction Whether or not globular clusters are single stellar populations has been debated for some time. To determine the presence of multiple populations one can plot the stars in a GC on a Hertzsprung-Russell diagram, which would indicate the main sequence of the individual GCs in the GC system as well as any turnoff points that would indicate the age of the stellar population. Most GCs we observe do not contain any gas that could trigger renewed star formation. The number of GCs with multiple stellar populations (MSP) is growing (Wang et al., 2017) as technology is improving. We now find MSP in most massive GCs. We also have compelling evidence for MSPs in most of the galactic GCs (Bastian & Lardo, 2017). One example of a GC with MSP is ! Centauri, which is the most massive Milky Way GC. The stars in ! Centauri were found to have a large spread of metallicities by Freeman & Rodgers (1975); Freeman & Norris (1981). Additional evidence was found in the form of multiple main sequence turnoffs (Sollima et al., 2005; Piotto, 2006) and multiple red giant branches (Lee et al., 1999; Pancino et al., 2000). All together this is compelling evidence for MSPs which are several Gyrs apart in age. It has been suggested by several studies (Zinnecker et al., 1988; Freeman, 1993; Gnedin et al., 2002) that ! Centauri is not what would classically be called a GC but instead is an ultra-compact dwarf galaxy, the stripped core of a galaxy that had in the past been acquired by the host galaxy (i.e the Milky Way). Regardless of the nature of omega centauri it is apparent that the view of GCs as simple stellar population systems is outdated. This could potentially change on how we use GC systems of tracers of galaxy formation histories. 1.2 Globular cluster systems A single galaxy can have tens of thousands of GCs associated with it. When talking about not a single but a multitude of GCs associated with the same galaxy, we refer to it as a GC system. Globular cluster systems have a long history of being used to constrain galaxy assembly histories (Ashman & Zepf, 1992; West et al., 2004; Brodie, 2009) and have further uses in inferring global properties of galaxies such as their mass. Their attributes such as individual GC radial velocities, spatial distribution and the presence of subpopulations (in the system not in individual GCs) are closely linked to their host galaxy's formation 1.3. Globular cluster systems and their host Galaxies 3 history. Not only are globular clusters observed in galaxies of all morphological types (Brodie & Strader, 2006; Harris et al., 2013), they offer the advantage of extending past the diffuse galaxy light, allowing the galaxy's potential to be probed out to galactic radii of ≥ 10Re (where Re refers to the effective radius of the host galaxy).
Load more

Recommended publications
  • VEGAS: a VST Early-Type Galaxy Survey. the Faint Substructures of NGC 4472 Stellar Halo
    VEGAS: A VST Early-type GAlaxy Survey. The faint substructures of NGC 4472 stellar halo. MARILENA SPAVONE ON THE BEHALF OF THE VEGAS TEAM: M. CAPACCIOLI, M. CANTIELLO, A. GRADO, E. IODICE, F. LA BARBERA, N.R. NAPOLITANO, C. TORTORA, L. LIMATOLA, M. PAOLILLO, T. PUZIA, R. PELETIER, A.J. ROMANOWSKY, D. FORBES, G. RAIMONDO OUTLINE The VST VEGAS survey Science aims Results on NGC 4472 field Conclusions Future plans MARILENA SPAVONE STELLAR HALOS 2015 ESO-GARCHING, 23-27 FEBRUARY THE VEGAS SURVEY Multiband u, g, r, i survey of ~ 110 galaxies with vrad < 4000 km/s in all environments (field to clusters). An example Obj. name Morph. type u g r i IC 1459 E3 5630 1850 1700 NGC 1399 E1 8100 5320 2700 NGC 3115 S0 14800 8675 6030 Observations to date (to P94) g-BAND ~ 16% i-BAND ~ 19% r-BAND ~ 3% + FORNAX u-BAND ~ 1% MARILENA SPAVONE STELLAR HALOS 2015 ESO-GARCHING, 23-27 FEBRUARY THE VEGAS SURVEY Multiband u, g, r, i survey of ~ 110 galaxies with vrad < 4000 km/s in all environments (field to clusters). OT ~ 350 h @ vst over 5 years Expected SB limits: 27.5 g, 2 27.0 r and 26.2 i mag/arcsec . g band expected SB limit MARILENA SPAVONE STELLAR HALOS 2015 ESO-GARCHING, 23-27 FEBRUARY THE VEGAS SURVEY Multiband u, g, r, i survey of ~ 110 galaxies with vrad < 4000 km/s in all environments (field to clusters). ~ 350 h @ vst over 5 years Expected SB limits: 27.5 g, 27.0 r and 26.2 i mag/arcsec2.
    [Show full text]
  • 198 7Apj. . .312L. .11J the Astrophysical Journal, 312:L11-L15
    .11J The Astrophysical Journal, 312:L11-L15,1987 January 1 .312L. © 1987. The American Astronomical Society. All rights reserved. Printed in U.S.A. 7ApJ. 198 INTERSTELLAR DUST IN SHAPLEY-AMES ELLIPTICAL GALAXIES M. Jura and D. W. Kim Department of Astronomy, University of California, Los Angeles AND G. R. Knapp and P. Guhathakurta Princeton University Observatory Received 1986 August 11; accepted 1986 September 30 ABSTRACT We have co-added the IRAS survey data at the positions of the brightest elliptical galaxies in the Revised Shapley-Ames Catalog to increase the sensitivity over that of the IRAS Point Source Catalog. More than half of 7 8 the galaxies (with Bj< \\ mag) are detected at 100 /xm with flux levels indicating, typically, 10 or 10 M0 of cold interstellar matter. The presence of cold gas in ellipticals thus appears to be the rule rather than the exception. Subject headings: galaxies: general — infrared: sources I. INTRODUCTION infrared emission from the elliptical galaxy in the line of sight. The traditional view of early-type galaxies is that they are Our criteria for a real detection are as follows: essentially free of interstellar matter. However, with advances 1. The optical position of the galaxy and the position of the in instrumental sensitivity, it has become possible to observe IRAS source agree to better than V. (The agreement is usually 21 cm emission (Knapp, Turner, and Cunniffe 1985; Wardle much better than T.) and Knapp 1986), optical dust patches (Sadler and Gerhard 2. The flux is at least 3 times the r.m.s. noise.
    [Show full text]
  • Radio Continuum and CO Emission in Star-Forming Galaxies
    A&A 385, 412–424 (2002) Astronomy DOI: 10.1051/0004-6361:20020140 & c ESO 2002 Astrophysics Radio continuum and CO emission in star-forming galaxies M. Murgia1,A.Crapsi1,2, L. Moscadelli3, and L. Gregorini1,4 1 Istituto di Radioastronomia del CNR, Via Gobetti 101, 40129, Bologna, Italy 2 Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125, Firenze, Italy 3 Osservatorio Astronomico di Cagliari, Loc. Poggio dei Pini, Strada 54, 09012 Capoterra (CA), Italy 4 Dipartimento di Fisica, Universit`a di Bologna, Via B. Pichat 6/2, 40127 Bologna, Italy Received 30 October 2001 / Accepted 23 January 2002 Abstract. We combine the radio continuum images from the NRAO VLA Sky Survey with the CO-line observations from the extragalactic CO survey of the Five College Radio Astronomy Observatory to study the relationship between molecular gas and the star formation rate within the disks of 180 spiral galaxies at 4500 resolution. We find a tight correlation between these quantities. On average, the ratio between the radio continuum and the CO emission is constant, within a factor of 3, both inside the same galaxy and from galaxy to galaxy. The mean star formation efficiency deduced from the radio continuum corresponds to convert 3.5% of the available molecular gas into stars on a time scale of 108 yr and depends weakly on general galaxy properties, such as Hubble type or nuclear activity. A comparison is made with another similar analysis performed using the Hα luminosity as star formation indicator. The overall agreement we find between the two studies reinforces the use of the radio luminosity as star formation rate indicator not only on global but also on local scales.
    [Show full text]
  • Stripped Elliptical Galaxies As Probes of Icm Physics. Ii
    The Astrophysical Journal, 806:104 (15pp), 2015 June 10 doi:10.1088/0004-637X/806/1/104 © 2015. The American Astronomical Society. All rights reserved. STRIPPED ELLIPTICAL GALAXIES AS PROBES OF ICM PHYSICS. II. STIRRED, BUT MIXED? VISCOUS AND INVISCID GAS STRIPPING OF THE VIRGO ELLIPTICAL M89 E. Roediger1,2,5, R. P. Kraft2, P. E. J. Nulsen2, W. R. Forman2, M. Machacek2, S. Randall2, C. Jones2, E. Churazov3, and R. Kokotanekova4 1 Hamburger Sternwarte, Universität Hamburg, Gojensbergsweg 112, D-21029 Hamburg, Germany; [email protected] 2 Harvard/Smithsonian Center for Astrophysics, 60 Garden Street MS-4, Cambridge, MA 02138, USA 3 MPI für Astrophysik, Karl-Schwarzschild-Str. 1, Garching D-85741, Germany 4 AstroMundus Master Programme, University of Innsbruck, Technikerstr. 25/8, 6020 Innsbruck, Austria Received 2014 September 18; accepted 2015 March 29; published 2015 June 10 ABSTRACT Elliptical galaxies moving through the intracluster medium (ICM) are progressively stripped of their gaseous atmospheres. X-ray observations reveal the structure of galactic tails, wakes, and the interface between the galactic gas and the ICM. This fine-structure depends on dynamic conditions (galaxy potential, initial gas contents, orbit in the host cluster), orbital stage (early infall, pre-/post-pericenter passage), as well as on the still ill-constrained ICM plasma properties (thermal conductivity, viscosity, magnetic field structure). Paper I describes flow patterns and stages of inviscid gas stripping. Here we study the effect of a Spitzer-like temperature dependent viscosity corresponding to Reynolds numbers, Re, of 50–5000 with respect to the ICM flow around the remnant atmosphere. Global flow patterns are independent of viscosity in this Reynolds number range.
    [Show full text]
  • Large-Scale Study of the NGC 1399 Globular Cluster System in Fornax
    A&A 451, 789–796 (2006) Astronomy DOI: 10.1051/0004-6361:20054563 & c ESO 2006 Astrophysics Large-scale study of the NGC 1399 globular cluster system in Fornax L. P. Bassino1,2, F. R. Faifer1,2,J.C.Forte1,B.Dirsch3, T. Richtler3, D. Geisler3, and Y. Schuberth4 1 CONICET and Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque S/N, 1900 La Plata, Argentina e-mail: [lbassino;favio;forte]@fcaglp.unlp.edu.ar 2 IALP - CONICET, Argentina 3 Universidad de Concepción, Departamento de Física, Casilla 160, Concepción, Chile e-mail: [email protected];[email protected];[email protected] 4 Sternwarte der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany e-mail: [email protected] Received 21 November 2005 / Accepted 6 January 2006 ABSTRACT We present a Washington C and Kron-Cousins R photometric study of the globular cluster system of NGC 1399, the central galaxy of the Fornax cluster. A large areal coverage of 1 square degree around NGC 1399 is achieved with three adjoining fields of the MOSAIC II Imager at the CTIO 4-m telescope. Working on such a large field, we can perform the first indicative determination of the total size of the NGC 1399 globular cluster system. The estimated angular extent, measured from the NGC 1399 centre and up to a limiting radius where the areal density of blue globular clusters falls to 30 per cent of the background level, is 45 ± 5arcmin,which corresponds to 220−275 kpc at the Fornax distance.
    [Show full text]
  • Chemistry and Star Formation in the Host Galaxies of Type Ia Supernovae
    Chemistry and Star Formation in the Host Galaxies of Type Ia Supernovae The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Gallagher, Joseph S., Peter M. Garnavich, Perry Berlind, Peter Challis, Saurabh Jha, and Robert P. Kirshner. 2005. “Chemistry and Star Formation in the Host Galaxies of Type Ia Supernovae.” The Astrophysical Journal 634 (1): 210–26. https:// doi.org/10.1086/491664. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:41399918 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA The Astrophysical Journal, 634:210–226, 2005 November 20 # 2005. The American Astronomical Society. All rights reserved. Printed in U.S.A. CHEMISTRY AND STAR FORMATION IN THE HOST GALAXIES OF TYPE Ia SUPERNOVAE Joseph S. Gallagher and Peter M. Garnavich Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556-5670 Perry Berlind F. L. Whipple Observatory, 670 Mount Hopkins Road, P.O. Box 97, Amado, AZ 85645 Peter Challis Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 Saurabh Jha Department of Astronomy, 601 Campbell Hall, University of California, Berkeley, CA 94720-3411 and Robert P. Kirshner Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 Received 2005 March 4; accepted 2005 July 22 ABSTRACT We study the effect of environment on the properties of Type Ia supernovae by analyzing the integrated spectra of 57 local Type Ia supernova host galaxies.
    [Show full text]
  • The Globular Cluster System of NGC 1399
    Astronomy & Astrophysics manuscript no. sch1399 c ESO 2018 August 28, 2018 The globular cluster system of NGC 1399 ⋆,⋆⋆ V. dynamics of the cluster system out to 80 kpc Y. Schuberth1,2, T. Richtler2, M. Hilker3, B. Dirsch2, L. P. Bassino4, A. J. Romanowsky5,2, and L. Infante6 1 Argelander-Institut f¨ur Astronomie, Universit¨at Bonn, Auf dem H¨ugel 71, D-53121 Bonn, Germany 2 Universidad de Concepci´on, Departamento de Astronomia, Casilla 160-C, Concepci´on, Chile 3 European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany 4 Facultad de Ciencias Astron´omicas y Geof´ısicas, Universidad Nacional de La Plata, Paseo del Bosque S/N, 1900–La Plata, Argentina; and Instituto de Astrof´ısica de La Plata (CCT La Plata – CONICET – UNLP) 5 UCO/Lick Observatory, University of California, Santa Cruz, CA 95064, USA 6 Departamento de Astronom´ıa y Astrof´ısica, Pontificia Universidad Cat´olica de Chile, Casilla 306, Santiago 22, Chile Received 14 May, 2009; accepted 16 October, 2009 ABSTRACT Globular clusters (GCs) are tracers of the gravitational potential of their host galaxies. Moreover, their kinematic properties may provide clues for understanding the formation of GC systems and their host galaxies. We use the largest set of GC velocities obtained so far of any elliptical galaxy to revise and extend the previous investigations (Richtler et al. 2004) of the dynamics of NGC 1399, the central dominant galaxy of the nearby Fornax cluster of galaxies. The GC velocities are used to study the kinematics, their relation with population properties, and the dark matter halo of NGC 1399.
    [Show full text]
  • Radial Distribution of Globular Clusters and Diffuse Hot
    Mon. Not. R. Astron. Soc. 000, 1–?? (2002) Printed 13 September 2018 (MN LATEX style file v2.2) The Baryonic Halos of Elliptical Galaxies: Radial Distribution of Globular Clusters and Diffuse Hot Gas Duncan A. Forbes1⋆, Trevor Ponman2 and Ewan O’Sullivan2,3, 1Centre for Astrophysics & Supercomputing, Swinburne University, Hawthorn VIC 3122, Australia 2School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT 3Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 13 September 2018 ABSTRACT For a sample of 9 well-studied giant ellipticals we compare the projected radial dis- tribution of their red and blue globular cluster (GC) subpopulations with their host galaxy stellar and X-ray surface brightness profiles. We support previous findings that the surface density distribution of red (metal-rich) GCs follows that of the host galaxy starlight. We find good agreement between the outer slope of the blue GC surface density and that of the galaxy X-ray emission. This coincidence of projected radial profiles is likely due to the fact that both blue GCs and X-ray emitting hot gas share the same gravitational potential in equilibrium. When deprojected the X-ray emitting hot gas has a radial density dependence that is the square root of that for the GC density. We further show that the energy per unit mass for blue GCs is roughly half that of the hot gas. Key words: globular clusters: general – galaxies: star clusters – galaxies: individual – galaxies: formation 1 INTRODUCTION common formation history with the stellar component of an elliptical galaxy. The globular cluster (GC) systems of most, well-studied large galaxies reveal evidence for two subpopulations in The blue GCs have been associated with elliptical colour (and by proxy in metallicity).
    [Show full text]
  • 115 Abell Galaxy Cluster # 373
    WINTER Medium-scope challenges 271 # # 115 Abell Galaxy Cluster # 373 Target Type RA Dec. Constellation Magnitude Size Chart AGCS 373 Galaxy cluster 03 38.5 –35 27.0 Fornax – 180 ′ 5.22 Chart 5.22 Abell Galaxy Cluster (South) 373 272 Cosmic Challenge WINTER Nestled in the southeast corner of the dim early winter western suburbs. Deep photographs reveal that NGC constellation Fornax, adjacent to the distinctive triangle 1316 contains many dust clouds and is surrounded by a formed by 6th-magnitude Chi-1 ( ␹ 1), Chi-2 ( ␹ 2), and complex envelope of faint material, several loops of Chi-3 ( ␹ 3) Fornacis, is an attractive cluster of galaxies which appear to engulf a smaller galaxy, NGC 1317, 6 ′ known as Abell Galaxy Cluster – Southern Supplement to the north. Astronomers consider this to be a case of (AGCS) 373. In addition to his research that led to the galactic cannibalism, with the larger NGC 1316 discovery of more than 80 new planetary nebulae in the devouring its smaller companion. The merger is further 1950s, George Abell also examined the overall structure signaled by strong radio emissions being telegraphed of the universe. He did so by studying and cataloging from the scene. 2,712 galaxy clusters that had been captured on the In my 8-inch reflector, NGC 1316 appears as a then-new National Geographic Society–Palomar bright, slightly oval disk with a distinctly brighter Observatory Sky Survey taken with the 48-inch Samuel nucleus. NGC 1317, about 12th magnitude and 2 ′ Oschin Schmidt camera at Palomar Observatory. In across, is visible in a 6-inch scope, although averted 1958, he published the results of his study as a paper vision may be needed to pick it out.
    [Show full text]
  • Virgo the Virgin
    Virgo the Virgin Virgo is one of the constellations of the zodiac, the group tion Virgo itself. There is also the connection here with of 12 constellations that lies on the ecliptic plane defined “The Scales of Justice” and the sign Libra which lies next by the planets orbital orientation around the Sun. Virgo is to Virgo in the Zodiac. The study of astronomy had a one of the original 48 constellations charted by Ptolemy. practical “time keeping” aspect in the cultures of ancient It is the largest constellation of the Zodiac and the sec- history and as the stars of Virgo appeared before sunrise ond - largest constellation after Hydra. Virgo is bordered by late in the northern summer, many cultures linked this the constellations of Bootes, Coma Berenices, Leo, Crater, asterism with crops, harvest and fecundity. Corvus, Hydra, Libra and Serpens Caput. The constella- tion of Virgo is highly populated with galaxies and there Virgo is usually depicted with angel - like wings, with an are several galaxy clusters located within its boundaries, ear of wheat in her left hand, marked by the bright star each of which is home to hundreds or even thousands of Spica, which is Latin for “ear of grain”, and a tall blade of galaxies. The accepted abbreviation when enumerating grass, or a palm frond, in her right hand. Spica will be objects within the constellation is Vir, the genitive form is important for us in navigating Virgo in the modern night Virginis and meteor showers that appear to originate from sky. Spica was most likely the star that helped the Greek Virgo are called Virginids.
    [Show full text]
  • CHEERS): Constraints on Turbulence
    A&A 575, A38 (2015) Astronomy DOI: 10.1051/0004-6361/201425278 & c ESO 2015 Astrophysics Chemical Enrichment RGS cluster Sample (CHEERS): Constraints on turbulence Ciro Pinto1, Jeremy S. Sanders2, Norbert Werner3,4, Jelle de Plaa5, Andrew C. Fabian1, Yu-Ying Zhang6, Jelle S. Kaastra5, Alexis Finoguenov7, and Jussi Ahoranta7 1 Institute of Astronomy, Madingley Road, CB3 0HA Cambridge, UK e-mail: [email protected]. 2 Max-Planck-Institut fur extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany 3 Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305-4085, USA 4 Department of Physics, Stanford University, 382 via Pueblo Mall, Stanford, CA 94305-4060, USA 5 SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands 6 Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany 7 Department of Physics, University of Helsinki, 00014 Helsinki, Finland Received 5 November 2014 / Accepted 24 December 2014 ABSTRACT Context. Feedback from active galactic nuclei, galactic mergers, and sloshing are thought to give rise to turbulence, which may prevent cooling in clusters. Aims. We aim to measure the turbulence in clusters of galaxies and compare the measurements to some of their structural and evolutionary properties. Methods. It is possible to measure the turbulence of the hot gas in clusters by estimating the velocity widths of their X-ray emission lines. The Reflection Grating Spectrometers aboard XMM-Newton are currently the only instruments provided with sufficient effective area and spectral resolution in this energy domain. We benefited from excellent 1.6 Ms new data provided by the Chemical Enrichment RGS cluster Sample (CHEERS) project.
    [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]