Differential population synthesis of early-type galaxies. III. Synthesis results

Journal Article · Sun Sep 15 04:00:00 EDT 1985 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/163454· OSTI ID:6328688

Pickles, A J

Synthesis results are presented for 12 elliptical and five lenticular galaxies which cover nearly a 6 mag range of absolute magnitude in the Fornax cluster (V = 1430 km s ). The results of age, metallicity, and mass-to-light ratio (M/L) determinations are presented differentially as functions of galactic luminosity and morphology. Bright elliptical galaxies are well represented by main-sequence turnoff colors of (V-R)/sub c/roughly-equal0.37 and B-Vroughly-equal0.70, in good agreement with O'Connell's results for bright Virgo ellipticals. The relatively young main-sequence turnoff ages, of 6-10 Gyr for ellipticals of all luminosities, indicate that substantial star formation activity occurred in these galaxies for a period of 6dagger10 Gyr after the epoch of globular cluster formation. There is strong evidence for small amounts of current star formation in at least the brightest ellipticals of all luminosities, indicate that substantial star formation in at least the brightest ellipticals, variation in the amount of which may account for significant dispersion in the cluster U-V versus V color-magnitude relation. A metallicity gradient in (Fe/H) of at least 0.16 dex per absolute magnitude is derived, with the brightest ellipticals being 2 to 3 times more metal-rich than solar. The mean metallicities and turnoff ages of the faintest ellipticals are probably dependent on environment. Distance-independent upper limits to galaxy M/L ratios derived from the syntheses conform well with M/L ratios derived from velocity dispersion measurements and give no evidence for unseen mass in the nuclei of early type galaxies of any luminosity.

• Research Organization: Mount Stromlo and Siding Spring Observatories, Research School of Physical Sciences, Australian National University
• OSTI ID: 6328688
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 296:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHEMICAL COMPOSITION
COMPUTER CODES
DATA ANALYSIS
DIAGRAMS
GALAXIES
HERTZSPRUNG-RUSSELL DIAGRAM
LUMINOSITY
MASS
MATHEMATICS
MORPHOLOGY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SPECTRA
STAR ACCRETION
STAR EVOLUTION
STATISTICS