Discovering Clues to Galaxy Evolution in the Radial Color Gradients of Late-type Spiral and Irregular Galaxies
Abstract
Radial color gradients of galaxies can provide an indication of stellar population or metalicity distribution differences between the inner and outer regions of a galaxy. This in turn may suggest certain mechanisms for how the galaxy was formed and evolved to its present state. Previous studies of radial color gradients have focused on elliptical and early to mid type spiral galaxies, determining that these galaxies either have no significant color gradient, or become bluer with increasing radius. We have measured gradients for 142 galaxies observed in UBVR at the Vatican Advanced Technology Telescope at Mt. Graham International Observatory. Most of these galaxies are late-type spiral, irregular, peculiar or merging galaxies, which are galaxy types that have not been studied extensively in the past, and are important for understanding high redshift galaxies that are apparently mostly irregular in morphology. We find that the late type spiral and irregular galaxies tend on average to become significantly redder with increasing radius, with a much larger scatter of possible gradients than exists in earlier galaxy types. This shows a fundamental difference between the color gradients of early type and most late type galaxies, which fits the predictions of models for hierarchical galaxy formation.
This research was partially funded by NASA grant GO-9174.01.* and the NASA Space Grant Graduate Fellowship at ASU. We wish to thank the staff of Steward Observatory and the Vatican Advanced Technology Telescope for all of their help and support on this project.- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2003
- Bibcode:
- 2003AAS...20314604T