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The VMC survey - XIV. First results on the look-back time star formation rate tomography of the Small Magellanic Cloud

Van Loon

The VMC survey - XIV. First results on the look-back time star formation rate tomography of the Small Magellanic Cloud Thumbnail


Authors



Abstract

We analyse deep images from the VISTA survey of the Magellanic Clouds in the YJKs filters, covering 14 deg2 (10 tiles), split into 120 subregions, and comprising the main body and Wing of the Small Magellanic Cloud (SMC). We apply a colour–magnitude diagram reconstruction method that returns their best-fitting star formation rate SFR(t), age–metallicity relation (AMR), distance and mean reddening, together with 68?per?cent confidence intervals. The distance data can be approximated by a plane tilted in the East–West direction with a mean inclination of 39°, although deviations of up to ±3 kpc suggest a distorted and warped disc. After assigning to every observed star a probability of belonging to a given age–metallicity interval, we build high-resolution population maps. These dramatically reveal the flocculent nature of the young star-forming regions and the nearly smooth features traced by older stellar generations. They document the formation of the SMC Wing at ages <0.2 Gyr and the peak of star formation in the SMC Bar at ~40 Myr. We clearly detect periods of enhanced star formation at 1.5 and 5 Gyr. The former is possibly related to a new feature found in the AMR, which suggests ingestion of metal-poor gas at ages slightly larger than 1 Gyr. The latter constitutes a major period of stellar mass formation. We confirm that the SFR(t) was moderately low at even older ages.

Citation

Van Loon. (2015). The VMC survey - XIV. First results on the look-back time star formation rate tomography of the Small Magellanic Cloud. Monthly Notices of the Royal Astronomical Society, 639 -661. https://doi.org/10.1093/mnras/stv141

Acceptance Date Jan 1, 2015
Publication Date May 1, 2015
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Pages 639 -661
DOI https://doi.org/10.1093/mnras/stv141
Keywords Hertzsprung–Russell and colour–magnitude diagrams, Magellanic Clouds
Publisher URL http://arxiv.org/abs/1501.05347

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