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Discovery of Intergalactic H II Regions

Published online by Cambridge University Press:  26 May 2016

E. V. Ryan-Weber ,
M. E. Putman ,
K. C. Freeman ,
G. R. Meurer  and
R. L. Webster
E. V. Ryan-Weber
Affiliation:
University of Melbourne, Australia
M. E. Putman
Affiliation:
CASA, University of Colorado, USA
K. C. Freeman
Affiliation:
RSSA, Australian National University, Australia
G. R. Meurer
Affiliation:
The Johns Hopkins University, USA
R. L. Webster
Affiliation:
University of Melbourne, Australia

Abstract

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We have discovered a number of very small isolated H II regions 20-30 kpc from their nearest galaxy. The H II regions appear as tiny emission line dots (ELdots) in narrow band images obtained by the NOAO Survey for Ionization in Neutral Gas Galaxies (SINGG). We have spectroscopic confirmation of 5 isolated H II regions in 3 systems. The Hα luminosities of the H II regions are equivalent to the ionizing flux of only 1 large or a few small OB stars each. These stars appear to have formed in situ and represent atypical star formation in the low density environment of galaxy outskirts. In situ star formation in the intergalactic medium offers an alternative to galactic wind models to explain metal enrichment. In interacting systems (2 out of 3), isolated H II regions could be a starting point for tidal dwarf galaxies.

Type
Part 4. Recycling
Information
Symposium - International Astronomical Union , Volume 217: Recycling Intergalactic and Interslettar Matter , 2004 , pp. 492 - 497
Copyright
Copyright © Astronomical Society of the Pacific 2004 

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