Imaging and spectrophotometry of Virgo cluster irregular galaxies

Abstract

Listen

Translate article

view Abstract Citations (68) References (74) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Imaging and Spectrophotometry of Virgo Cluster Irregular Galaxies Gallagher, John S., III ; Hunter, Deidre A. Abstract Large-aperture spectrophotometric observations and CCD images in the Hα and R bands are presented for Virgo Cluster Magellanic, dwarf and amorphous irregular galaxies. These data provide a basis for comparisons between star-forming properties, morphologies, and emission-line characteristics in field and cluster irregular galaxies. Most Virgo Cluster Magellanic and dwarf irregular galaxies are optically similar to field galaxies. Modest cluster-field differences may exist in H I gas content (cluster lower than field) and in star-formation rates per unit area (cluster lower than field). A minority of Virgo Cluster irregulars have optical and H I properties consistent with recent gas loss, but the rate of production of gas-poor irregulars is too low to account for the large population of Virgo Cluster dE galaxies or to explain the deficiency in the number of irregulars relative to spirals. Also puzzling are the properties of red amorphous or peculiar E/S0 galaxies in our sample. Radial brightness profiles have been measured for these galaxies, and only NGC 4641 follows the r^1/4^ law of classical ellipticals, four galaxies have exponential brightness distributions, and one system has an indeterminant profile form. The physical nature of the red amorphous galaxies thus remains unclear. We also suggest that the properties of Virgo Cluster irregular galaxies are best understood in terms of environmental modifications of normal systems in the circumcluster environment and in the cluster core. However, these processes do not appear to account for the large core region population of dE galaxies, and thus initial conditions may also have played a role in shaping the Virgo Cluster dwarf galaxy population. Publication: The Astronomical Journal Pub Date: September 1989 DOI: 10.1086/115180 Bibcode: 1989AJ.....98..806G Keywords: Astronomical Photometry; Dwarf Galaxies; Irregular Galaxies; Spectrophotometry; Virgo Galactic Cluster; Astronomical Catalogs; Brightness Distribution; Density Distribution; H I Regions; Magellanic Clouds; Visual Photometry; Astrophysics; GALAXIES: GENERAL full text sources ADS | data products SIMBAD (43) NED (41)