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1999MNRAS.304....8H - Mon. Not. R. Astron. Soc., 304, 8-26 (1999/March-3)
Late-type dwarf irregular galaxies in the Virgo cluster - I. H-alpha and red continuum data.
HELLER A., ALMOZNINO E. and BROSCH N.
Abstract (from CDS):
For those objects in the LSB sample with Hα emission, we find typical star formation rates (SFRs) from 6.9x10–3 to as high as 4.3x10–2 M☉.yr–1. This is, on average, one order of magnitude weaker than for HSB objects, although the SFRs overlap. On average, ∼2 HII regions are detected per LSB galaxy, for a total of 38 HII regions among 17 galaxies with Hα emission. The HII regions are smaller and fainter than in HSB galaxies in the same Virgo cluster environment, have Hα line equivalent widths about 50 per cent of those in HSBs, and cover similar fractions of the galaxies. When more than one HII region is present in a galaxy, we observe a strong intensity difference between the brightest and the second brightest HII regions. The line-emitting regions of LSB galaxies are preferentially located at the periphery of the galaxy, while in HSBs they tend to be central. The Hα line strength of an HII region is correlated with the red continuum light underneath the region; this holds for both LSBs and HSBs.
We do not identify fundamental differences in the star formation properties of the LSB and HSB dwarf galaxies that we have studied, and we infer that these galaxies must be similar, with the difference being the intensity of the present star formation burst.
Abstract Copyright: 1999, Royal Astronomical Society
Journal keyword(s): stars: formation - HII regions - galaxies: clusters: individual: Virgo - galaxies: irregular - galaxies: stellar content
Simbad objects: 45
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