Star formation in early type galaxies

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6337283

Caldwell, C N

Observational studies of the recent star formation histories in SO and elliptical galaxies are described in this thesis. A photometric system using a broad-band color combined with a line strength index is used to distinguish age differences from metalliciy differences between the bulges and disks of SO galaxies. A color difference of ..delta..(U-V) approx. 0.10 is found for the sample of galaxies observed here. Several SOs have absorption line strengths that indicate the disks are as metal rich as the most luminous ellipticals. It in concluded that the disks of SOs are younger than the bulges, but the distinction between a younger turnoff and residual star formation cannot be made. The case for star formation in ellipticals is reviewed as a prelude to several new observational studies which indicate that the phenomenon does exist. The rate of Type I supernova in early type galaxies is higher for galaxies that are in regions where gas stripping processes are unlikely to be present than is the rate in dense clusters. The color magnitude relation for ellipticals is shown to give information not only on the dependence of metallicity on luminosity, but also non the relative amounts of young stars in ellipticals. The residuals in color at a given luminsity are due mostly to variations in the proportion of young stars in the galaxies. Ellipticals that do not reside in dense clusters are in the mean bluer by 0.10 in U-V than those in dense clusters. An appendix on the surface brightness profiles of the dwarf ellipticals is also presented.

• Research Organization: Yale Univ., New Haven, CT (USA)
• OSTI ID: 6337283
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION SPECTRA
AGE ESTIMATION
COLOR
CONFIGURATION
COSMIC GASES
ELLIPTICAL CONFIGURATION
EMISSION SPECTRA
ERUPTIVE VARIABLE STARS
FLUIDS
GALAXIES
GASES
LUMINOSITY
OPTICAL PROPERTIES
ORGANOLEPTIC PROPERTIES
PHOTOMETRY
PHYSICAL PROPERTIES
SPECTRA
STAR EVOLUTION
STARS
SUPERNOVAE
VARIABLE STARS