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

Journal Article · Sun Sep 15 00:00:00 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), Vol. 296:2
• Country of Publication: United States
• Language: English

Related Subjects

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