{"paper":{"title":"Panchromatic Hubble Andromeda Treasury. XIX. The Ancient Star Formation History of the M31 Disk","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.GA","authors_text":"Alexia R. Lewis, Andrew E. Dolphin, Antonela Monachesi, Benjamin F. Williams, Daniel R. Weisz, Eric F. Bell, Evan Skillman, Julianne J. Dalcanton, Philip Rosenfield, Yumi Choi","submitted_at":"2017-08-08T19:30:48Z","abstract_excerpt":"We map the star formation history across M31 by fitting stellar evolution models to color-magnitude diagrams of each 83$''{\\times}$83$''$ (0.3$\\times$1.4 kpc, deprojected) region of the PHAT survey outside of the innermost 6$'{\\times}$12$'$ portion. We find that most of the star formation occurred prior to $\\sim$8 Gyr ago, followed by a relatively quiescent period until $\\sim$4 Gyr ago, a subsequent star formation episode about 2 Gyr ago and a return to relative quiescence. There appears to be little, if any, structure visible for populations with ages older than 2 Gyr, suggesting significant "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1708.02617","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}