A GLOBAL STAR-FORMING EPISODE IN M31 2-4 GYR AGO

作者：Williams Benjamin F^*; Dalcanton Julianne J; Dolphin Andrew E; Weisz Daniel R; Lewis Alexia R; Lang Dustin; Bell Eric F; Boyer Martha; Fouesneau Morgan; Gilbert Karoline M; Monachesi Antonela; Skillman Evan

来源：Astrophysical Journal, 2015, 806(1): 48.

DOI：10.1088/0004-637X/806/1/48

• galaxies: evolution
• galaxies: individual (M31)
• galaxies: interactions

We have identified a major global enhancement of star formation in the inner M31 disk that occurred between 2-4 Gyr ago, producing similar to 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.

• 出版日期2015-6-10