Massive star formation in galaxies with excess UV emission

Abstract

From an analysis of almost 2000 GALEX images of galaxies with morphological types ranging from E to Sab, we have found a significant subset (28%) that show UV emission outside $R_{25}$. We have obtained H$\alpha$ imaging of ten such galaxies, and find that their star formation rates are similar in the UV and in H$\alpha$, with values ranging from a few tenths to a few $M_{\odot }$ yr${}^{-1}$. Probably because our sample selection is biased towards star-forming galaxies, these rates are comparable to those found in disk galaxies, although the star formation rates of the elliptical galaxies in our sample are well below $1M_{\odot }$ yr${}^{-1}$. We confirm that the extended UV emission in our sample is caused by massive star formation in outer spiral arms and/or outer (pseudo) rings, rather than by alternative mechanisms such as the UV upturn.

13 pages, 3 figures, to be published in MNRAS

References in corpus (7)

• The GALEX Ultraviolet Atlas of Nearby Galaxies
• UV Dust Attenuation in Star-forming Galaxies: II Calibrating the A(UV) vs. L_TIR/L_UV relation
• Galaxy-scale Star Formation on the Red Sequence: the Continued Growth of S0s and the Quiescence of Ellipticals
• Star Formation Laws: the Effects of Gas Cloud Sampling
• A composite HII region luminosity function in H alpha of unprecedented statistical weight
• HST/ACS observations of shell galaxies: inner shells, shell colours and dust
• Hα Kinematics of S4G spiral galaxies-I. NGC 864

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• Study of central light distribution in nearby early-type galaxies hosting nuclear star clusters