Astron. J., 143, 133 (2012/June-0)
Gas, stars, and star formation in ALFALFA dwarf galaxies.
HUANG S., HAYNES M.P., GIOVANELLI R., BRINCHMANN J., STIERWALT S. and NEFF S.G.
Abstract (from CDS):
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 < 107.7 M☉and H I line widths < 80 km/s. 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* ≲ 108 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.
galaxies: dwarf - galaxies: evolution - galaxies: fundamental parameters - galaxies: star formation - radio lines: galaxies - surveys
VizieR on-line data:
<Available at CDS (J/AJ/143/133): table1.dat>
AGC 112505, 174514, 191791, 205097, 205165, 213796 and 220609 are not in Simbad.
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