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The massive star clusters in the dwarf merger ESO 185−IG13: is the red excess ubiquitous in starbursts?

Adamo, A. ; Östlin, G. ; Zackrisson, E. ; Hayes, M.

In: Monthly Notices of the Royal Astronomical Society, 2011, vol. 414, no. 3, p. 1793-1812

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    Titre
    • The massive star clusters in the dwarf merger ESO 185−IG13: is the red excess ubiquitous in starbursts?
    Auteur
    • Adamo, A.. Department of Astronomy, Stockholm University, Oscar Klein Centre, AlbaNova, Stockholm SE-106 91, Sweden
    • Östlin, G.. Department of Astronomy, Stockholm University, Oscar Klein Centre, AlbaNova, Stockholm SE-106 91, Sweden
    • Zackrisson, E.. Department of Astronomy, Stockholm University, Oscar Klein Centre, AlbaNova, Stockholm SE-106 91, Sweden
    • Hayes, M.. Observatoire Astronomique de l'Université de Genève, 51 ch des Maillettes, CH-1290 Sauverny, Switzerland
    Type de document
    • Postprint
    Langue
    • Inglese
    Publié dans
    • Monthly Notices of the Royal Astronomical Society, 2011, vol. 414, no. 3, p. 1793-1812. Blackwell Publishing Ltd
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:301559
    Summary
    We have investigated the starburst properties of the luminous blue compact galaxy ESO 185−IG13. The galaxy has been imaged with the high-resolution cameras onboard the Hubble Space Telescope. From the ultraviolet (UV) to the infrared (IR), the data reveal a system shaped by hundreds of young star clusters, and fine structures, like a tidal stream and a shell. The presence of numerous clusters and the perturbed morphology indicate that the galaxy has been involved in a recent merger event. Using previous simulations of shell formation in galaxy mergers we constrain potential progenitors of ESO 185−IG13. The analysis of the star cluster population is used to investigate the properties of the present starburst and to date the final merger event, which has produced hundreds of clusters younger than 100 Myr. We have found a peak of cluster formation only 3.5 Myr old. A large fraction of these clusters will not survive after 10-20 Myr due to the ‘infant mortality' caused by gas expulsion. However, this sample of clusters represents a unique chance to investigate the youngest phases of cluster evolution. As already observed in the analogue blue compact galaxy Haro 11, a fraction of young clusters are affected by a flux excess at wavelengths longer than 8000 Å. Ages, masses and extinctions of clusters with this near-IR (NIR) excess are estimated from UV and optical data. We discuss similarities and differences of the observed NIR excess in ESO 185−IG13 clusters with other cases in the literature. The cluster ages and masses are used to distinguish among the potential causes of the excess. We observe, as in Haro 11, that the use of the IR and the (commonly used) I band data results in overestimates of age and mass in clusters affected by the NIR excess. This has important implications for a number of related studies of star clusters