Star Formation History in the Small Magellanic Cloud: The Case of NGC 602

• Published in: The Astronomical journal 2009-03, Vol.137 (3), p.3668-3684
• Main Authors: Cignoni, M, Sabbi, E, Nota, A, Tosi, M, Degl'Innocenti, S, Moroni, P. G. Prada, Angeretti, L, Carlson, Lynn Redding, Gallagher, J, Meixner, M, Sirianni, M, Smith, L. J
• Format: Article
• Language: English
• ISSN: 1538-3881; 0004-6256; 1538-3881
• DOI: 10.1088/0004-6256/137/3/3668

Deep Hubble Space Telescope/Advanced Camera for Surveys photometry of the young cluster NGC 602, located in the remote low-density 'wing' of the Small Magellanic Cloud (SMC), reveals numerous pre-main-sequence (PMS) stars as well as young stars on the main sequence. The resolved stellar content thus provides a basis for studying the star formation history (SFH) into recent times and constraining several stellar population properties, such as the present-day mass function (PDMF), the initial mass function, and the binary fraction. To better characterize the PMS population, we present a new set of model stellar evolutionary tracks for this evolutionary phase with metallicity appropriate for the SMC (Z = 0.004). We use a stellar population synthesis code, which takes into account a full range of stellar evolution phases to derive our best estimate for the SFH in the region by comparing observed and synthetic color-magnitude diagrams. The derived PDMF for NGC 602 is consistent with that resulting from the synthetic diagrams. The star formation rate in the region has increased with time on a scale of tens of Myr, reaching (0.3-0.7) X 10-3 M yr-1 in the last 2.5 Myr, comparable to what is found in Galactic OB associations. Star formation is most complete in the main cluster but continues at moderate levels in the gas-rich periphery of the nebula.