Luminosity Functions for Old Stellar Systems
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Baltic Astronomy, vol. 24, 213{220, 2015 VELOCITY DISPERSION OF IONIZED GAS AND MULTIPLE SUPERNOVA EXPLOSIONS E. O. Vasiliev1;2;3, A. V. Moiseev3;4 and Yu. A. Shchekinov2 1 Institute of Physics, Southern Federal University, Stachki Ave. 194, Rostov-on-Don, 344090 Russia; [email protected] 2 Department of Physics, Southern Federal University, Sorge Str. 5, Rostov-on-Don, 344090 Russia 3 Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnij Arkhyz, Karachaevo-Cherkesskaya Republic, 369167 Russia 4 Sternberg Astronomical Institute, Moscow M. V. Lomonosov State University, Universitetskij pr. 13, 119992 Moscow, Russia Received: 2015 March 25; accepted: 2015 April 20 Abstract. We use 3D numerical simulations to study the evolution of the Hα intensity and velocity dispersion for single and multiple supernova (SN) explosions. We find that the IHα{ σ diagram obtained for simulated gas flows is similar in shape to that observed in dwarf galaxies. We conclude that collid- ing SN shells with significant difference in age are responsible for high velocity dispersion that reaches up to ∼> 100 km s−1. Such a high velocity dispersion could be hardly obtained for a single SN remnant. Peaks of velocity disper- sion in the IHα{ σ diagram may correspond to several isolated or merged SN remnants with moderately different ages. Degrading the spatial resolution in the Hα intensity and velocity dispersion maps makes the simulated IHα{ σ di- agrams close to those observed in dwarf galaxies not only in shape, but also quantitatively. Key words: galaxies: ISM { ISM: bubbles { ISM: supernova remnants { ISM: kinematics and dynamics { shock waves { methods: numerical 1. -
IRFM T$ {\Sf\Sl Eff}$ Calibrations for Cluster and Field Giants in the Vilnius, Geneva, RI$ {\Sf\Sl (C)}$ and DDO Photometric Sy
A&A 417, 301–316 (2004) Astronomy DOI: 10.1051/0004-6361:20031764 & c ESO 2004 Astrophysics IRFM Teff calibrations for cluster and field giants in the Vilnius, Geneva, RI(C) and DDO photometric systems I. Ram´ırez1,2 and J. Mel´endez1,3 1 Seminario Permanente de Astronom´ıa y Ciencias Espaciales, Universidad Nacional Mayor de San Marcos, Ciudad Universitaria, Facultad de Ciencias F´ısicas, Av. Venezuela s/n, Lima 1, Per´u 2 Department of Astronomy, The University of Texas at Austin, RLM 15.202A, TX 78712-1083, USA 3 Department of Astronomy, California Institute of Technology, MC 105–24, Pasadena, CA 91125, USA Received 2 May 2003 / Accepted 19 November 2003 Abstract. Based on a large sample of disk and halo giant stars for which accurate effective temperatures derived through the InfraRed Flux Method (IRFM) exist, a calibration of the temperature scale in the Vilnius, Geneva, RI(C) and DDO photometric systems is performed. We provide calibration formulae for the metallicity-dependent Teff vs. color relations as well as grids of intrinsic colors and compare them with other calibrations. Photometry, atmospheric parameters and reddening corrections for the stars of the sample have been updated with respect to the original sources to reduce the dispersion of the fits. Application of our results to Arcturus leads to an effective temperature in excellent agreement with the value derived from its angular diameter and integrated flux. The effects of gravity on these Teff vs. color relations are also explored by taking into account our previous results for dwarf stars. Key words. -
Investigating [X/Fe], Imf and Compositeness in Integrated Models
INVESTIGATING [X/FE], IMF AND COMPOSITENESS IN INTEGRATED MODELS By BAITIAN TANG A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY WASHINGTON STATE UNIVERSITY Department of Physics and Astronomy MAY 2015 c Copyright by BAITIAN TANG, 2015 All Rights Reserved c Copyright by BAITIAN TANG, 2015 All Rights Reserved To the Faculty of Washington State University: The members of the Committee appointed to examine the dissertation of BAITIAN TANG find it satisfactory and recommend that it be accepted. Guy Worthey Ph.D., Chair Sukanta Bose, Ph.D. Matthew Duez, Ph.D. ii ACKNOWLEDGEMENT First and foremost I offer my sincerest gratitude to my advisor, Dr. Guy Worthey, who supported my study and research with motivation, enthusiasm, and immense knowledge. There were times when research funding was scarce, but his optimism, diligence and patience taught me the true meanings of research. Dr. Worthey gave me lots of free space in pursuing the research that interested me, and backed me up with his astrophysical proficiency. I would also like to thank the rest of my committee members: Dr. Sukanta Bose, and Dr. Matthew Duez for their encouragements and comments. Their courses, general relativity and astrophysical fluids, have expanded my eyesight to a much broader horizon. My sincere thanks also go to Dr. Qiusheng Gu and Dr. Zhaohui Shang, who supported my job applications and gave many insightful suggestions. During my Ph.D. study, I have been blessed with a friendly and cheerful group of fellow students. We enjoyed the great life and culture of the northwest. -
Environmental Influences on Dwarf Galaxy Evolution: the Group Environment
ENVIRONMENTAL INFLUENCES ON DWARF GALAXY EVOLUTION: THE GROUP ENVIRONMENT A Dissertation Presented to the Faculty of the Graduate School of Cornell University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy by Sabrina Renee Stierwalt February 2010 c 2010 Sabrina Renee Stierwalt ALL RIGHTS RESERVED ENVIRONMENTAL INFLUENCES ON DWARF GALAXY EVOLUTION: THE GROUP ENVIRONMENT Sabrina Renee Stierwalt, Ph.D. Cornell University 2010 Galaxy groups are a rich source of information concerning galaxy evolution as they represent a fundamental link between individual galaxies and large scale structures. Nearby groups probe the low end of the galaxy mass function for the dwarf systems that constitute the most numerous extragalactic population in the local universe [Karachentsev et al., 2004]. Inspired by recent progress in our understanding of the Local Group, this dissertation addresses how much of this knowledge can be applied to other nearby groups by focusing on the Leo I Group at 11 Mpc. Gas-deficient, early-type dwarfs dominate the Local Group (Mateo [1998]; Belokurov et al. [2007]), but a few faint, HI-bearing dwarfs have been discovered in the outskirts of the Milky Way’s influence (e.g. Leo T; Irwin et al. [2007]). We use the wide areal coverage of the Arecibo Legacy Fast ALFA (ALFALFA) HI survey to search the full extent of Leo I and exploit the survey’s superior sensitivity, spatial and spectral resolution to probe lower HI masses than previous HI surveys. ALFALFA finds in Leo I a significant population of low surface brightness dwarfs missed by optical surveys which suggests similar systems in the Local Group may represent a so far poorly studied population of widely distributed, optically faint yet gas-bearing dwarfs. -