Galaxy spectral synthesis. II. M32 and the ages of galaxies

Journal Article · Sat Mar 01 04:00:00 EST 1980 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/157759· OSTI ID:5430033

O'Connell, R W

We perform a population synthesis on absolute spectrophotometry for the central 31'' of M32. The main-sequence turnoff is at (B--V)approx.0.5 or F8 equivalent spectral type. A variety of models for cooler turnoffs are considered and found to be excluded by the data. The metallicity of M32 is solar within approx.0.1 dex. Taken together, these results imply that major star formation continued in M32 until approx.5 Gyr ago, or 10 Gyr after the oldest globular clusters formed. Perhaps 50% of the giant light could arise in a significantly older population, and the peak star formation rate could have occurred much earlier. However, significant changes in the colors of low-mass elliptical galaxies are expected at lookback time of approx.5 Gyr. The anomalously blue galaxies now being observed in distant clusters may be such objects. A tentative age dating for gE nuclei indicates an upper limit for the turnoff age of 6--8 Gyr.

• Research Organization: Department of Astronomy, University of Virginia
• OSTI ID: 5430033
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 236:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHEMICAL COMPOSITION
ENERGY SPECTRA
GALAXIES
GALAXY NUCLEI
MAIN SEQUENCE STARS
NEBULAE
PLANETARY NEBULAE
SPECTRA
SPECTROPHOTOMETRY
STAR EVOLUTION
STARS