Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2009-09-15
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
Accepted for publication in AJ, 39 pages, 13 Postscript figures. High resolution available at: http://www.iac.es/galeria/noe
Scientific paper
We present a quantitative analysis of the SFH of 12 fields in the SMC. We find that there are four main periods of enhancement of star formation: a young one peaked at around 0.2-0.5 Gyr old, only present in the eastern and in the central-most fields; two at intermediate ages present in all fields (a conspicuous one peaked at 4-5 Gyr old, and a less significant one peaked at 1.5-2.5); and an old one, peaked at 10 Gyr in all fields but the western ones. In the western fields, this old enhancement splits into two, one peaked at around 8 Gyr old and another at around 12 Gyr old. This "two-enhancement" zone seems to be a robust feature since it is unaffected by our choice of stellar evolutionary library but more data covering other fields of the SMC are necessary in order to ascertain its significancy. Some correlation could exist with encounters taken from the orbit determination of Kallivayalil et al. (2006). But our results would be also fit in a first pericenter passage scenario like the one claimed by Besla et al. (2007). There is a strong dichotomy between East/Southeast and West in the current irregular shape of the SMC. We find that this dichotomy is produced by the youngest population and began about 1 Gyr ago or later. We do not find yet a region dominated by an old halo at 4.5 kpc from the SMC center, indicating either that this old stellar halo does not exist in the SMC or that its contribution to the stellar populations, at the galactocentric distances of our outermost field, is negligible. We derive the age-metallicity relation and find that the metallicity increased continuously from early epochs until now.
Aparicio Antonio
Costa Edgardo
Gallart Carme
Hidalgo Sebastian L.
Mendez Rene A.
No associations
LandOfFree
Old Main Sequence Turnoff Photometry in the Small Magellanic Cloud. II. Star Formation History and Its Spatial Gradients 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 Old Main Sequence Turnoff Photometry in the Small Magellanic Cloud. II. Star Formation History and Its Spatial Gradients, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Old Main Sequence Turnoff Photometry in the Small Magellanic Cloud. II. Star Formation History and Its Spatial Gradients will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-581850