GALEX ULTRAVIOLET IMAGING OF DWARF GALAXIES AND STAR FORMATION RATES

Journal Article · Mon Feb 15 04:00:00 EST 2010 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/139/2/447; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21301380

Hunter, Deidre A; Ludka, Bonnie C ^[1]

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1. Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States)

We present ultraviolet-integrated and azimuthally averaged surface photometric properties of a sample of 44 dwarf irregular (dIm), blue compact dwarf, and Sm galaxies measured from archival near-ultraviolet (NUV) and far-ultraviolet (FUV) images obtained with the Galaxy Evolution Explorer (GALEX). We compare the UV to H{alpha} and V-band properties and convert FUV, H{alpha}, and V-band luminosities into star formation rates (SFRs). We also model the star formation history from colors and compare the integrated SFRs and SFR profiles with radius for these methods. In most galaxies, the UV photometry extends beyond H{alpha} in radius, providing a better measure of the star formation activity in the outer disks. The H{alpha} appears to be lacking in the outer disk because of faintness in low-density gas. The FUV and V-band profiles are continuous with radius, although they sometimes have a kink from a double exponential disk. There is no obvious difference in star formation properties between the inner and outer disks. No disk edges have been observed, even to stellar surface densities as low as 0.1 M {sub sun} pc{sup -2} and SFRs as low as 10{sup -4} M {sub sun} yr{sup -1} kpc{sup -2}. Galaxies with low H I to luminosity ratios have relatively low FUV compared to V-band emission in the outer parts, suggesting a cessation of star formation there. Galaxies with relatively high H I apparently have fluctuating star formation with a gigayear timescale.

• OSTI ID: 21301380
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 2 Vol. 139; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
FAR ULTRAVIOLET RADIATION
GALACTIC EVOLUTION
GALAXIES
LUMINOSITY
PHOTOMETRY
STARS