Detalles de publicación
PP 013067
Massive star formation in galaxies with excess UV emission
(1)Instituto de Astrof ́ısica de Canarias, V ́ıa La ́ctea s/n 38205 La Laguna, Spain
(2)Departamento de Astrof ́ısica, Universidad de La Laguna, 38206 La Laguna, Spain
(3)School of Physics and Astronomy, University of St Andrews, North Haugh, Fife KY16 9SS St Andrews, UK
(4)Department of Astronomy, University of Wisconsin - Madison, 475 N. Charter St., Madison, WI, 53706, USA
(5)Department of Astronomy & Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802, USA
(6)Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802, USA
(7)The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101, USA
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 $1\,M_{\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.