Volume 575, March 2015
|Number of page(s)||18|
|Section||Galactic structure, stellar clusters and populations|
|Published online||24 February 2015|
No evidence for significant age spreads in young massive LMC clusters⋆
1 European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching bei München, Germany
2 Universitäts-Sternwarte München, Scheinerstraße 1, 81679 München, Germany
3 Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
4 Centre de Recherche en Astrophysique du Québec (CRAQ), Université Laval, 1045 Avenue de la Médecine, G1V 0A6 Québec, Canada
5 FACom-Instituto de Física-FCEN, Universidad de Antioquia, Calle 70 No. 52-21, Medellín, Colombia
Received: 23 June 2014
Accepted: 20 December 2014
Recent discoveries have put the picture of stellar clusters being simple stellar populations into question. In particular, the color–magnitude diagrams of intermediate age (1–2 Gyr) massive clusters in the Large Magellanic Cloud (LMC) show features that could be interpreted as age spreads of 100–500 Myr. If multiple generations of stars are present in these clusters then, as a consequence, young (<1 Gyr) clusters with similar properties should have age spreads of the same order. In this paper we use archival Hubble Space Telescope (HST) data of eight young massive LMC clusters (NGC 1831, NGC 1847, NGC 1850, NGC 2004, NGC 2100, NGC 2136, NGC 2157 and NGC 2249) to test this hypothesis. We analyzed the color–magnitude diagrams of these clusters and fitted their star formation history to derive upper limits of potential age spreads. We find that none of the clusters analyzed in this work shows evidence for an extended star formation history that would be consistent with the age spreads proposed for intermediate age LMC clusters. Tests with artificial single age clusters show that the fitted age dispersion of the youngest clusters is consistent with spreads that are purely induced by photometric errors. As an additional result we determined a new age of NGC 1850 of ~100 Myr, significantly higher than the commonly used value of about 30 Myr, although consistent with early HST estimates.
Key words: galaxies: star clusters: general / Magellanic Clouds / Hertzsprung-Russell and C-M diagrams / stars: evolution
Based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA) and the Canadian Astronomy Data Centre (CADC/NRC/CSA).
© ESO, 2015
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