SIMBAD references

2005AJ....129.2597H - Astron. J., 129, 2597-2616 (2005/June-0)

Hα imaging of early-type Sa-Sab spiral galaxies. II. Global properties.


Abstract (from CDS):

New results, based on one of the most comprehensive Hα imaging surveys of nearby Sa-Sab spirals completed to date, reveals early-type spirals to be a diverse group of galaxies that span a wide range in massive star formation rates. While the majority of Sa-Sab galaxies in our sample are forming stars at a modest rate, a significant fraction (∼29%) exhibit star formation rates greater than 1 M/yr, rivaling the most prolifically star-forming late-type spirals. A similar diversity is apparent in the star formation history of Sa-Sab spirals as measured by their Hα equivalent widths. Consistent with our preliminary results presented in the first paper in this series, we find giant H II regions [L(Hα)≥1039 ergs/s] in the disks of ∼37% of early-type spirals. We suspect that recent minor mergers or past interactions are responsible for the elevated levels of Hα emission and, perhaps, for the presence of giant H II regions in these galaxies. Our results, however, are not in total agreement with the Hα study of Kennicutt & Kent, who did not find any early-type spirals with Hα equivalent widths >14 Å. A close examination of the morphological classification of galaxies, however, suggests that systematic differences between the Revised Shapley-Ames Catalog and the Second Reference Catalogue may be responsible for the contrasting results.

Abstract Copyright:

Journal keyword(s): Galaxies: Evolution - Galaxies: ISM - Galaxies: Photometry - Galaxies: Spiral - ISM: H II Regions

Simbad objects: 52

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