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A galex ultraviolet imaging survey of galaxies in the local volume

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Lee, anice C. and Gil de Paz, Armando and Kennicutt, Robert C., Jr. and Bothwell, Matthew and Dalcanton, Julianne and Funes, Jose G. S. J. and Johnson, Benjamin D. and Sakai, Shoko and Skillman, Evan and Tremonti, Christy and van Zee, Liese (2011) A galex ultraviolet imaging survey of galaxies in the local volume. Astrophysical journal supplement series, 192 (1). ISSN 0067-0049

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Official URL: http://dx.doi.org/10.1088/0067-0049/192/1/6


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http://iopscience.iop.org/Publisher


Abstract

We present results from a GALEX ultraviolet (UV) survey of a complete sample of 390 galaxies within ~11 Mpc of the Milky Way. The UV data are a key component of the composite Local Volume Legacy, an ultraviolet-to-infrared imaging program designed to provide an inventory of dust and star formation in nearby spiral and irregular galaxies. The ensemble data set is an especially valuable resource for studying star formation in dwarf galaxies, which comprise over 80% of the sample. We describe the GALEX survey programs that obtained the data and provide a catalog of far-UV (~1500 Å) and near-UV (~2200 Å) integrated photometry. General UV properties of the sample are briefly discussed. We compute two measures of the global star formation efficiency, the star formation rate (SFR) per unit H I gas mass, and the SFR per unit stellar mass, to illustrate the significant differences that can arise in our understanding of dwarf galaxies when the FUV is used to measure the SFR instead of Hα. We find that dwarf galaxies may not be as drastically inefficient in converting gas into stars as suggested by prior Hα studies. In this context, we also examine the UV properties of late-type dwarf galaxies that appear to be devoid of star formation because they were not detected in previous Hα narrowband observations. Nearly all such galaxies in our sample are detected in the FUV and have FUV SFRs that fall below the limit where the Hα flux is robust to Poisson fluctuations in the formation of massive stars. Otherwise, the UV colors and star formation efficiencies of Hα-undetected, UV-bright dwarf irregulars appear to be relatively unremarkable with respect to those exhibited by the general population of star-forming galaxies.


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© 2011. The American Astronomical Society. All rights reserved. GALEX is a NASA Small Explorer, and 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. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA, as well as the HyperLeda database (http://leda.univ-lyon1.fr). We thank the anonymous referee for useful feedback which helped to clarify some important points in our interpretation of the data. Special thanks are due to Chris Martin and the members of the GALEX team (http://www.galex.caltech.edu/about/team.html) for their dedicated support of the Guest Investigator Program, without which this work would not have been possible. A.G.d.P. is supported by the Spanish "Ramón y Cajal", Plan Nacional AYA2009-10368, Consolider-GTC and AstroMadrid (CAM S2009/ESP-1496) programs.

Uncontrolled Keywords:Dwarf irregular galaxies; Star-forming galaxies; Initial mass functions; H-alpha; Formation histories; Nearby galaxies; Disk galaxies; Formation demographics; Luminosity function; Physical-properties
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:35483
Deposited On:02 Feb 2016 15:50
Last Modified:10 Dec 2018 15:05

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