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Gas, Stars, and Star Formation in ALFALFA Dwarf Galaxies

Huang, Shan and Haynes, Martha P. and Giovanelli, Riccardo and Brinchmann, Jarle and Stierwalt, Sabrina and Neff, Susan G. (2012) Gas, Stars, and Star Formation in ALFALFA Dwarf Galaxies. Astronomical Journal, 143 (6). p. 133. ISSN 0004-6256. doi:10.1088/0004-6256/143/6/133.

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We examine the global properties of the stellar and H I components of 229 low H_I mass dwarf galaxies extracted from the ALFALFA survey, including a complete sample of 176 galaxies with H_I masses <10^(7.7) M_☉ and H_I line widths <80 km s^(–1). Sloan Digital Sky Survey (SDSS) data are combined with photometric properties derived from Galaxy Evolution Explorer to derive stellar masses (M_*) and star formation rates (SFRs) by fitting their UV-optical spectral energy distributions (SEDs). In optical images, many of the ALFALFA dwarfs are faint and of low surface brightness; only 56% of those within the SDSS footprint have a counterpart in the SDSS spectroscopic survey. A large fraction of the dwarfs have high specific star formation rates (SSFRs), and estimates of their SFRs and M_* obtained by SED fitting are systematically smaller than ones derived via standard formulae assuming a constant SFR. The increased dispersion of the SSFR distribution at M_* ≲ 10^8 M_☉ is driven by a set of dwarf galaxies that have low gas fractions and SSFRs; some of these are dE/dSphs in the Virgo Cluster. The imposition of an upper H_I mass limit yields the selection of a sample with lower gas fractions for their M_* than found for the overall ALFALFA population. Many of the ALFALFA dwarfs, particularly the Virgo members, have H_I depletion timescales shorter than a Hubble time. An examination of the dwarf galaxies within the full ALFALFA population in the context of global star formation (SF) laws is consistent with the general assumptions that gas-rich galaxies have lower SF efficiencies than do optically selected populations and that H_I disks are more extended than stellar ones.

Item Type:Article
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Haynes, Martha P.0000-0001-5334-5166
Giovanelli, Riccardo0000-0001-8884-8492
Stierwalt, Sabrina0000-0002-2596-8531
Additional Information:© 2012 American Astronomical Society. Received 2011 October 7; accepted 2012 March 11; published 2012 April 30. The authors acknowledge the work of the entire ALFALFA collaboration team in observing, flagging, and extracting the catalog of galaxies used in this work. The ALFALFA team at Cornell is supported by NSF grant AST-0607007 and AST- 1107390 and by grants from the Brinson Foundation. GALEX is a NASA Small Explorer, launched in 2003 April. We gratefully acknowledge NASA’s support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the Centre National d’Etudes Spatiales of France and the Korean Ministry of Science and Technology. S.H., S.S., and M.P.H. acknowledge support for this work from the GALEX Guest Investigator program under NASA grants NNX07AJ12G, NNX08AL67G, and NNX09AF79G. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the NASA, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute forAdvanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max Planck Institute for Astronomy, the MPA, New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington.
Subject Keywords:galaxies: dwarf; galaxies: evolution; galaxies: fundamental parameters; galaxies: star formation; radio lines: galaxies; surveys
Issue or Number:6
Record Number:CaltechAUTHORS:20120612-112536239
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Official Citation:Gas, Stars, and Star Formation in ALFALFA Dwarf Galaxies Shan Huang et al. 2012 The Astronomical Journal 143 133
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:31878
Deposited By: Jason Perez
Deposited On:12 Jun 2012 20:43
Last Modified:09 Nov 2021 20:01

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