Interstellarum 31 1 10 24
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
The Andromeda Galaxy's Most Important Merger
The Andromeda Galaxy’s most important merger ~ 2 Gyrs ago as M32’s likely progenitor Richard D’Souza* & Eric F. Bell Although the Andromeda Galaxy’s (M31) proximity offers a singular opportunity to understand how mergers affect galaxies1, uncertainty remains about M31’s most important mergers. Previous studies focused individually on the giant stellar stream2 or the impact of M32 on M31’s disk3,4, thereby suggesting many significant satellite interactions5. Yet, models of M31’s disk heating6 and the similarity between the stellar populations of different tidal substructures in M31’s outskirts7 both suggested a single large merger. M31’s outer low- surface brightness regions (its stellar halo) is built up from the tidal debris of satellites5 and provides decisive guidance about its important mergers8. Here we use cosmological models of galaxy formation9,10 to show that M31’s massive11 and metal-rich12 stellar halo, containing intermediate-age stars7, dramatically narrows the range of allowed interactions, requiring a 10 single dominant merger with a large galaxy (M*~2.5x10 M¤, the third largest member of the Local Group) ~2 Gyr ago. This single event explains many observations that were previously considered separately: its compact and metal-rich satellite M3213 is likely to be the stripped core of the disrupted galaxy, M31’s rotating inner stellar halo14 contains most of the merger debris, and the giant stellar stream15 is likely to have been thrown out during the merger. This interaction may explain M31’s global burst of star formation ~2 Gyr ago16 in which ~1/5 of its stars were formed. -
September 2005
Amateur astronomers get better looking... Pay club dues at the General Meeting, or by mail. $30 individual, $40 family Volume 25 Number 9 nightwatch September 2005 President’s Address August General Meeting Summer is nearly over; autumn is almost here. Two visitors joined our meeting, Chris Peterson and In the upcoming months we have planned a public star James, along with a long time member who doesn’t get party at Barnes & Noble Booksellers in Rancho a chance to come to our meetings very often, William Cucamonga. We have had several events in Fritz. We look forward to seeing them all again soon. conjunction with Barnes & Noble and they have all Lee Collins’ What’s Up for the month discussed the been fun. The next one will be on the evening of Summer Triangle and the many nebulae to be seen in Thursday, October 13th. th this area which also contains views of our own Milky On October 29 we will have a joint star party Way when the sky is dark enough. While two of the with the Riverside Astronomical Society at their site near Landers. It will be interesting to see the many Star Party Sites improvements, which have been made to site since the (MBC) Mecca Beach Campground last time we were there. The Riverside group is a great (CS) Cottonwood Springs campground, Joshua Tree Natl. Pk bunch and this will be a lot of fun. (CC) Cow Canyon Saddle, near Mount Baldy Village We will have our Mars observing session with (MS) Mesquite Springs campground, Death Valley National Pk the 60-inch telescope on Mount Wilson Friday, (CWP) Claremont Wilderness Park parking lot November 11th. -
The Dipole Anisotropy of the 2 Micron All-Sky Redshift Survey
Mon. Not. R. Astron. Soc. 368, 1515–1526 (2006) doi:10.1111/j.1365-2966.2006.10243.x The dipole anisotropy of the 2 Micron All-Sky Redshift Survey Downloaded from https://academic.oup.com/mnras/article-abstract/368/4/1515/1151639 by MIDDLE EAST TECHNICAL UNIVERSITY LIBRARY user on 24 July 2020 , P. Erdo˘gdu,1,2 J. P. Huchra,3 O. Lahav,2 4 M. Colless,5 R. M. Cutri,6 E. Falco,3 T. George,7 T. Jarrett,6 D. H. Jones,8 C. S. Kochanek,9 L. Macri,10 J. Mader,11 N. Martimbeau,3 M. Pahre,3 Q. Parker,12 A. Rassat4 and W. Saunders5,13 1Department of Physics, Middle East Technical University, 06531 Ankara, Turkey 2School of Physics & Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD 3Harvard-Smithsonian Center of Astrophysics, 60 Garden Street, MS-20, Cambridge, MA 02138, USA 4Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT 5Anglo-Australian Observatory, PO Box 296, Epping, NSW 2052, Australia 6Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA 7California Institute of Technology, 4800 Oak Grove Drive, 302-231, Pasadena, CA 91109, USA 8Research School of Astronomy and Astrophysics, Mount Stromlo, and Siding Spring Observatories, Cotter Road, Weston Creek, ACT 2611, Australia 9Department of Astronomy, Ohio State University, 4055 McPherson Lab, 140 West 18th Avenue, Columbus, OH 43221, USA 10National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85726, USA 11W.M. Keck Observatory, Kamuela, HI 96743, USA 12Department of Physics, Macquarie University, Sydney, NWS 2109, Australia 13Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ Accepted 2006 February 23. -
Neutral Hydrogen in Local Group Dwarf Galaxies
Neutral Hydrogen in Local Group Dwarf Galaxies Jana Grcevich Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of Arts and Sciences COLUMBIA UNIVERSITY 2013 c 2013 Jana Grcevich All rights reserved ABSTRACT Neutral Hydrogen in Local Group Dwarfs Jana Grcevich The gas content of the faintest and lowest mass dwarf galaxies provide means to study the evolution of these unique objects. The evolutionary histories of low mass dwarf galaxies are interesting in their own right, but may also provide insight into fundamental cosmological problems. These include the nature of dark matter, the disagreement be- tween the number of observed Local Group dwarf galaxies and that predicted by ΛCDM, and the discrepancy between the observed census of baryonic matter in the Milky Way’s environment and theoretical predictions. This thesis explores these questions by studying the neutral hydrogen (HI) component of dwarf galaxies. First, limits on the HI mass of the ultra-faint dwarfs are presented, and the HI content of all Local Group dwarf galaxies is examined from an environmental standpoint. We find that those Local Group dwarfs within 270 kpc of a massive host galaxy are deficient in HI as compared to those at larger galactocentric distances. Ram- 4 3 pressure arguments are invoked, which suggest halo densities greater than 2-3 10− cm− × out to distances of at least 70 kpc, values which are consistent with theoretical models and suggest the halo may harbor a large fraction of the host galaxy’s baryons. We also find that accounting for the incompleteness of the dwarf galaxy count, known dwarf galaxies whose gas has been removed could have provided at most 2.1 108 M of HI gas to the Milky Way. -
Draft181 182Chapter 10
Chapter 10 Formation and evolution of the Local Group 480 Myr <t< 13.7 Gyr; 10 >z> 0; 30 K > T > 2.725 K The fact that the [G]alactic system is a member of a group is a very fortunate accident. Edwin Hubble, The Realm of the Nebulae Summary: The Local Group (LG) is the group of galaxies gravitationally associ- ated with the Galaxy and M 31. Galaxies within the LG have overcome the general expansion of the universe. There are approximately 75 galaxies in the LG within a 12 diameter of ∼3 Mpc having a total mass of 2-5 × 10 M⊙. A strong morphology- density relation exists in which gas-poor dwarf spheroidals (dSphs) are preferentially found closer to the Galaxy/M 31 than gas-rich dwarf irregulars (dIrrs). This is often promoted as evidence of environmental processes due to the massive Galaxy and M 31 driving the evolutionary change between dwarf galaxy types. High Veloc- ity Clouds (HVCs) are likely to be either remnant gas left over from the formation of the Galaxy, or associated with other galaxies that have been tidally disturbed by the Galaxy. Our Galaxy halo is about 12 Gyr old. A thin disk with ongoing star formation and older thick disk built by z ≥ 2 minor mergers exist. The Galaxy and M 31 will merge in 5.9 Gyr and ultimately resemble an elliptical galaxy. The LG has −1 vLG = 627 ± 22 km s with respect to the CMB. About 44% of the LG motion is due to the infall into the region of the Great Attractor, and the remaining amount of motion is due to more distant overdensities between 130 and 180 h−1 Mpc, primarily the Shapley supercluster. -
Index to JRASC Volumes 61-90 (PDF)
THE ROYAL ASTRONOMICAL SOCIETY OF CANADA GENERAL INDEX to the JOURNAL 1967–1996 Volumes 61 to 90 inclusive (including the NATIONAL NEWSLETTER, NATIONAL NEWSLETTER/BULLETIN, and BULLETIN) Compiled by Beverly Miskolczi and David Turner* * Editor of the Journal 1994–2000 Layout and Production by David Lane Published by and Copyright 2002 by The Royal Astronomical Society of Canada 136 Dupont Street Toronto, Ontario, M5R 1V2 Canada www.rasc.ca — [email protected] Table of Contents Preface ....................................................................................2 Volume Number Reference ...................................................3 Subject Index Reference ........................................................4 Subject Index ..........................................................................7 Author Index ..................................................................... 121 Abstracts of Papers Presented at Annual Meetings of the National Committee for Canada of the I.A.U. (1967–1970) and Canadian Astronomical Society (1971–1996) .......................................................................168 Abstracts of Papers Presented at the Annual General Assembly of the Royal Astronomical Society of Canada (1969–1996) ...........................................................207 JRASC Index (1967-1996) Page 1 PREFACE The last cumulative Index to the Journal, published in 1971, was compiled by Ruth J. Northcott and assembled for publication by Helen Sawyer Hogg. It included all articles published in the Journal during the interval 1932–1966, Volumes 26–60. In the intervening years the Journal has undergone a variety of changes. In 1970 the National Newsletter was published along with the Journal, being bound with the regular pages of the Journal. In 1978 the National Newsletter was physically separated but still included with the Journal, and in 1989 it became simply the Newsletter/Bulletin and in 1991 the Bulletin. That continued until the eventual merger of the two publications into the new Journal in 1997. -
Galaxies Discovered Behind the Milky Way by the Dwingeloo Obscured Galaxies Survey P. A. Henning Institute for Astrophysics
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server Galaxies Discovered Behind the Milky Way by the Dwingeloo Obscured Galaxies Survey P. A. Henning Institute for Astrophysics, University of New Mexico 800 Yale Blvd., NE, Albuquerque, NM 87131 R. C. Kraan-Korteweg Observatoire de Paris-Meudon, D.A.E.C. 92195 Meudon Cedex, France and Astronomy Department, University of Guanajuato Apartado Postal 144, Guanajuato, GTO 36000, Mexico A. J. Rivers Institute for Astrophysics, University of New Mexico 800 Yale Blvd., NE, Albuquerque, NM 87131 A. J. Loan Institute of Astronomy, University of Cambridge Madingley Road, Cambridge CB3 0HA, UK O. Lahav Institute of Astronomy, University of Cambridge Madingley Road, Cambridge CB3 0HA, UK and Anglo Australian Observatory P.O. Box 296, Epping, NSW 2121, Australia W. B. Burton Leiden Observatory Postbus 9513, NL-2300 RA Leiden, The Netherlands 1 Abstract Our Galaxy blocks a significant portion of the extragalactic sky from view, hampering studies of large-scale structure. This produces an incom- plete knowledge of the distribution of galaxies, and, assuming galaxies trace mass, of the gravity field. Further, just one unrecognized, nearby massive galaxy could have large influence over the Milky Way’s motion with respect to the Cosmic Microwave Background. Diligent surveys in the optical and infrared wavebands can find galaxies through moderate Galactic gas and dust, but close to the Galactic Plane, only radio surveys are effective. The entire northern Zone of Avoidance is being searched at 21 cm for galaxies using the Dwingeloo 25-m telescope. -
Andromeda IX: a New Dwarf Spheroidal Satellite Of
Andromeda IX: A New Dwarf Spheroidal Satellite of M31 Daniel B. Zucker1,10, Alexei Y. Kniazev1, Eric F. Bell1, David Mart´inez-Delgado1, Eva K. Grebel1,2, Hans-Walter Rix1, Constance M. Rockosi3, Jon A. Holtzman4, Rene A. M. Walterbos4, James Annis5, Donald G. York6, Zeljkoˇ Ivezi´c7, J. Brinkmann8, Howard Brewington8, Michael Harvanek8, Greg Hennessy9, S. J. Kleinman8, Jurek Krzesinski8, Dan Long8, Peter R. Newman8, Atsuko Nitta8, Stephanie A. Snedden8 ABSTRACT We report the discovery of a new dwarf spheroidal satellite of M31, An- dromeda IX, based on resolved stellar photometry from the Sloan Digital Sky Survey (SDSS). Using both SDSS and public archival data we have estimated its distance and other physical properties, and compared these to the properties of a previously known dwarf spheroidal companion, Andromeda V, also observed by SDSS. Andromeda IX is the lowest surface brightness galaxy found to date −2 (µV,0 ∼ 26.8 mag arcsec ), and at the distance we estimate from the position of the tip of Andromeda IX’s red giant branch, (m − M)0 ∼ 24.5 (805 kpc), Andromeda IX would also be the faintest galaxy known (MV ∼ −8.3). Subject headings: galaxies: dwarf — galaxies: individual (Andromeda V) — galaxies: individual (Andromeda IX) — galaxies: evolution — Local Group 1Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, D-69117 Heidelberg, Germany; [email protected] 2Astronomisches Institut, Universit¨at Basel, Venusstrasse 7,CH-4102 Binningen, Switzerland arXiv:astro-ph/0404268v2 16 Aug 2004 3Astronomy Department, University of Washington, Box 351580, Seattle WA 98195-1580 4Department of Astronomy, New Mexico State University, 1320 Frenger Mall, Las Cruces NM 88003-8001 5Fermi National Accelerator Laboratory, P.O. -
Astronomy 2009 Index
Astronomy Magazine 2009 Index Subject Index 1RXS J160929.1-210524 (star), 1:24 4C 60.07 (galaxy pair), 2:24 6dFGS (Six Degree Field Galaxy Survey), 8:18 21-centimeter (neutral hydrogen) tomography, 12:10 93 Minerva (asteroid), 12:18 2008 TC3 (asteroid), 1:24 2009 FH (asteroid), 7:19 A Abell 21 (Medusa Nebula), 3:70 Abell 1656 (Coma galaxy cluster), 3:8–9, 6:16 Allen Telescope Array (ATA) radio telescope, 12:10 ALMA (Atacama Large Millimeter/sub-millimeter Array), 4:21, 9:19 Alpha (α) Canis Majoris (Sirius) (star), 2:68, 10:77 Alpha (α) Orionis (star). See Betelgeuse (Alpha [α] Orionis) (star) Alpha Centauri (star), 2:78 amateur astronomy, 10:18, 11:48–53, 12:19, 56 Andromeda Galaxy (M31) merging with Milky Way, 3:51 midpoint between Milky Way Galaxy and, 1:62–63 ultraviolet images of, 12:22 Antarctic Neumayer Station III, 6:19 Anthe (moon of Saturn), 1:21 Aperture Spherical Telescope (FAST), 4:24 APEX (Atacama Pathfinder Experiment) radio telescope, 3:19 Apollo missions, 8:19 AR11005 (sunspot group), 11:79 Arches Cluster, 10:22 Ares launch system, 1:37, 3:19, 9:19 Ariane 5 rocket, 4:21 Arianespace SA, 4:21 Armstrong, Neil A., 2:20 Arp 147 (galaxy pair), 2:20 Arp 194 (galaxy group), 8:21 art, cosmology-inspired, 5:10 ASPERA (Astroparticle European Research Area), 1:26 asteroids. See also names of specific asteroids binary, 1:32–33 close approach to Earth, 6:22, 7:19 collision with Jupiter, 11:20 collisions with Earth, 1:24 composition of, 10:55 discovery of, 5:21 effect of environment on surface of, 8:22 measuring distant, 6:23 moons orbiting, -
1977Apj. . .217 . .903Y the Astrophysical Journal, 217
.903Y . .217 The Astrophysical Journal, 217:903-915, 1977 November 1 . © 1977. The American Astronomical Society. All rights reserved. Printed in U.S.A. 1977ApJ. THE LOCAL GROUP: THE SOLAR MOTION RELATIVE TO ITS CENTROID A. Yahil,* G. A. Tammann, and Allan Sandage Hale Observatories, Carnegie Institution of Washington, California Institute of Technology Received 1976 October 29; accepted 1977 April 29 ABSTRACT A new solution for the motion of the local standard of rest (LSR) relative to the centroid of the Local Group (LG) of galaxies, based on 21 cm redshifts for a number of candidates, gives i;(LSR) = 300 km s_1 toward / = 107°, b = —8°. Three other solutions are given using different precepts for membership within the LG. This motion of the LSR corresponds to a best-fit -1 o solar motion relative to the LG centroid of ^(0) = 308 km s toward / = 105°, b = —I . Consideration of the velocity residuals from the ridge-line solution of each candidate galaxy shows that the sometimes-mentioned galaxies IC 342, NGC 6946, NGC 404, and Maffei 1 and 2 are certainly not members. Likely members, on the basis of the kinematics alone, are IC 10, Pegasus dwarf, WLM, DDO 210, Leo A, and IC 5152. Possible, but unlikely, members, again based on kinematics alone, are DDO 187, GR 8, Sextans A and B, and NGC 3109. All five of these latter galaxies have positive residuals of about 125 km s-1 relative to the solution, and may be the nearest galaxies that show the cosmological expansion. A discussion of the error matrix is given, with special emphasis on breaking up the velocity v0 of the LSR relative to the centroid of the LG into the sum of a rotation velocity vc and the motion of the center of the Galaxy vG. -
Interstellarum 22 1 30 38
Liebe Leserinnen, liebe Leser, das Sternbild Skorpion gehört zu denjenigen Himmelsarealen, die von Mitteleuropa aus nur kurz zu beobachten sind. Trotzdem tummeln sich gerade hier eine große Anzahl interessanter Deep-Sky-Objekte. Neben Doppelsternen (Seite 47) und Veränderlichen (Seite 49) gehören dazu vor allem großflächige Emissions- und Reflexions- nebel. Diese bunteste Region des Himmels ist von unseren Breiten aus allerdings kaum zu erfassen und erfordert Reisen auf die Südhalbku- gel. Stefan Binnewies war in Afrika und zeigt uns auf tiefen Farbaufnahmen die Himmelswunder im nördlichen Skorpion zwischen den Zangen des Krabbeltiers (Seite 44). Die aufregenden süd- lichen, für Mitteleuropäer unter dem Horizont Ikeya Zhang (Foto: Martin Bender) befindlichen Nebellandschaften hatten wir bereits in interstellarum 16 vorgestellt. Das Team des Turtle Star Observatory um Axel Der Komet Ikeya-Zhang hat uns alle beglückt. Martin hat unter dem dunklen namibischen Him- Nach langer Pause war mit ihm endlich wieder mel fünf aktuelle Negativfilme für die Deep-Sky- ein Schweifstern aufgetaucht, der schön mit blo- Fotografie getestet (Seite 60). Dieser Test ist einer ßem Auge zu erkennen war. Aus den zahlreichen der Bestandteile des neuen Oculum-Buches Bildeinsendungen vieler Leser haben wir die »Astrofotografie in fünf Schritten«. Für jeden Ein- schönsten Abbildungen zusammengestellt (Seite steiger verständlich erklärt Axel Martin dort den 38). Im nächsten Heft werden wir noch den Aus- Weg zum erfolgreichen Astrofotografen. Neben klang der Ikeya-Zhang-Show feiern und weitere Tipps für die richtige Ausrüstung steht dabei vor Aufnahmen von Ihnen veröffentlichen. allem die praxisorientierte Problemlösung im Vordergrund. Wir möchten dieses Buch aus unse- Astrofotografie ist ungebrochen populär, gera- rem Hause jedem angehenden Astrofotografen de auch die chemische Variante. -
Bright Nebula Observing Program
Contact information: Inside this issue: Info Officer (General Info) – [email protected] Website Administrator – [email protected] Page January Club Calendar 3 Postal Address: Fort Worth Astronomical Society Tandy Hills Star Party Info 4 c/o Matt McCullar Cloudy Nights Review 5.,6 5801 Trail Lake Drive Fort Worth, TX 76133 Celestial Events 7 Web Site: http://www.fortworthastro.org (or .com) Object of the Month 8 Facebook: http://tinyurl.com/3eutb22 Twitter: http://twitter.com/ftwastro AL Observing Program 9,10,11,12 Yahoo! eGroup (members only): http://tinyurl.com/7qu5vkn ISS visibility info 13 Officers (2018-2020): Planetary Visibility info 13 President – Chris Mlodnicki , [email protected] Vice President – Fred Klich , [email protected] Sky Chart for Month 14 Tres – Laura Cowles, [email protected] Lunar Calendar 15 Secretary—Pam Klich, [email protected] Lunar Info 16 Board Members: Mars/Saturn Data 17 2018-2020 Phil Stage Fundraising/Donation Info 18,19 Robin Pond Photo Files 20 John McCrea Pam Kloepfer Cover Photo: IC1848 Photo via Alberto Pisabarro Observing Site Reminders: Be careful with fire, mind all local burn bans! Dark Site Usage Requirements (ALL MEMBERS): • Maintain Dark-Sky Etiquette (http://tinyurl.com/75hjajy) • Turn out your headlights at the gate! Ed itor : • Sign the logbook (in camo-painted storage shed. Inside the door on the left- hand side) George C. Lutch • Log club equipment problems (please contact a FWAS board member to inform them of any problems) • Put equipment back neatly when finished Issue Contribu- • Last person out: to rs : Check all doors – secured, but NOT locked Make sure nothing is left out Pa m K l ic h The Fort Worth Astronomical Society (FWAS) was founded in 1949 and is a non-profit 501(c)3 Matt McCullar scientific educational organization, and incorporated in the state of Texas.