Andromeda Galaxy

Astronomers have divided imagery of the Andromeda galaxy taken by NASA’s Hubble Space Telescope into thousands of squares 300 light-years on a side and determined the history of star formation within each parcel to gain a comprehensive view of the galaxy’s past. This image highlights two such regions.Massive stars are bluer and short-lived, while less massive stars are redder and longer-lived. As a result, areas that have experienced recent star formation (1) tend to have a larger fraction of blue stars, while areas with less recent star formation (2) typically have a redder population.Massive stars are bluer and short-lived, while less massive stars are redder and longer-lived. As a result, areas that have experienced recent star formation (1) tend to have a larger fraction of blue stars, while areas with less recent star formation (2) typically have a redder population.Data of M31 were obtained from the HST PHAT and PHAST Treasury proposals: P.I. J. Dalcanton and B. Williams (University of Washington) et al. 12058, 12073, 12109, 12107, 12074, 12105, 12113, 12075, 12057, 12111, 12115, 12071, 12114, 12072, 12056, 12106, 12059, 12108, 12110, 12112, 12055, 12076, 12070, 16778, 16778, 16796, 16796, 16797, 16797, 16798, 16798, 16799, 16799, 16800, 16800, 16801

Image Description: The left half of the disk of the Andromeda galaxy, with a jagged outer edge at the top and bottom on a black background. At right, the galaxy’s center is a horizontal yellow oval extending across about a third of the image. Two crescent shaped clumpy, dark dust lanes with abundant stars throughout extend out from the center. The galaxy becomes bluer as you move outward. At top middle, the satellite galaxy M32 appears as a small, fuzzy yellow oval. Within the disk of Andromeda, two regions at upper right and lower middle are outlined in small white boxes labeled 1 and 2, respectively. At the left side of the image, those two regions are enlarged in pullouts. Both contain a dense, grainy-appearing field of thousands of stars. Region 1 is noticeably bluer than region 2 and contains blue star-forming clumps.