A Global Star-forming Episode in M31 2-4 Gyr Ago
Abstract
We have identified a major global enhancement of star formation in the inner M31 disk that occurred between 2-4 Gyr ago, producing ∼60% of the stellar mass formed in the past 5 Gyr. The presence of this episode in the inner disk was discovered by modeling the optical resolved star color-magnitude diagrams of low extinction regions in the main disk of M31 (3 < R < 20 kpc) as part of the Panchromatic Hubble Andromeda Treasury. This measurement confirms and extends recent measurements of a widespread star formation enhancement of similar age in the outer disk, suggesting that this burst was both massive and global. Following the galaxy-wide burst, the star formation rate of M31 has significantly declined. We briefly discuss possible causes for these features of the M31 evolutionary history, including interactions with M32, M33, and/or a merger.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2015
- DOI:
- arXiv:
- arXiv:1504.02120
- Bibcode:
- 2015ApJ...806...48W
- Keywords:
-
- galaxies: evolution;
- galaxies: individual: M31;
- galaxies: interactions;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 12 pages, 2 tables, 6 figures, accepted for publication in ApJ
