The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER). II. The Spatially Resolved Recent Star Formation History of M33

Abstract We measure the spatially resolved recent star formation history (SFH) of M33 using optical images taken with Hubble Space Telescope as part Panchromatic Andromeda Treasury: Triangulum Extended Region (PHATTER) survey. The area covered by observations used in this analysis covers a de-projected ?38 kpc 2 and extends to ?3.5 ?2 from center along major semimajor axes, respectively. divide PHATTER survey into 2005 regions that 24 arcsec, ?100 pc, on side fit color–magnitude diagrams for each region individually SFH within footprint. There are significant fluctuations small spatial scales also galaxy-wide we back about 630 Myr ago. observe more flocculent spiral structure stellar populations younger than 80 Myr, while older is dominated two arms. bar M33, which dominates at ages Myr. Finally, find mean rate (SFR) over last 100 footprint 0.32 ± 0.02 M ? yr ?1 . current SFR (over 10 Myr) 0.20 0.03 This slightly higher previous measurements broadband estimates, when scaled account fraction D25