Astronomy and Astrophysics – Astrophysics
Scientific paper
2003-04-04
Astron.J. 126 (2003) 187
Astronomy and Astrophysics
Astrophysics
24 pages, 10 figures accepted for publication in Astronomical Journal
Scientific paper
10.1086/375761
We present a measurement of the star formation history of Sextans A, based on WFPC2 photometry that is 50% complete to V=27.5 (M_V ~+ 1.9) and I=27.0. The star formation history and chemical enrichment history have been measured through modeling of the CMD. We find evidence for increased reddening in the youngest stellar populations and an intrinsic metallicity spread at all ages. Sextans A has been actively forming stars at a high rate for ~ 2.5 Gyr ago, with an increased rate beginning ~ 0.1 Gyr ago. We find a non-zero number of stars older than 2.5 Gyr, due to the limited depth of the photometry, a detailed star formation history at intermediate and older ages has considerable uncertainties. The mean metallicity was found to be [M/H] ~- 1.4 over the measured history of the galaxy, with most of the enrichment happening at ages of at least 10 Gyr. We also find that an rms metallicity spread of 0.15 dex at all ages allows the best fits to the observed CMD. We revisit our determination of the recent star formation history (age <= 0.7 Gyr) using BHeB stars and find good agreement for all but the last 25 Myr, a discrepancy resulting primarily from different distances used in the two analyses and the differential extinction in the youngest populations. This indicates that star formation histories determined solely from BHeB stars should be confined to CMD regions where no contamination from reddened MS stars is present.
Cole Andrew A.
Dohm-Palmer Robbie C.
Dolphin Andrew E.
Gallagher Jay S.
Hoessel John G.
No associations
LandOfFree
Deep HST Imaging of Sextans A. III. The Star Formation History does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Deep HST Imaging of Sextans A. III. The Star Formation History, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Deep HST Imaging of Sextans A. III. The Star Formation History will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-143209