The Stellar Populations of Nearby Early-Type Galaxies
Abstract
We have obtained high quality spectra of 120 early-type galaxies with the 1.5m telescope at the F. L. Whipple Observatory. The sample galaxies are from both the Virgo cluster and the nearby field environment and cover a large range in central velocity dispersion (50 km/s <σ < 300 km/s), magnitude (-16.5 <MB< -22.0) and morphology (E, S0, dE, dS0). With a wavelength coverage of 3500 <λ < 5500, a FWHM resolution of 1.8 Å , and a typical S/N of 50 or better near Hδ , the spectra are ideal for analyzing the stellar populations of the sample galaxies. To determine the star formation histories, we use a variety of spectral indices, especially those of absorption lines in the blue, including the age-sensitive higher order Balmer lines. Our spectra show that the lower mass galaxies have a considerable range in absorption line strengths while the higher mass galaxies are relatively homogeneous. Based on the line strengths alone, we find that nearly 30% of the low mass galaxies in the sample show evidence of recent star formation, while less than 5% of the more massive galaxies do. The detailed star formation history of the sample is further analyzed with stellar population models.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AAS...199.7803C