Low mass pre-main sequence stars in the Large Magellanic Cloud

Free access article

Issue		A&A Volume 446, Number 3, February II 2006


Page(s)		955 - 969
Section		Galactic structure, stellar clusters and populations
DOI		http://dx.doi.org/10.1051/0004-6361:20053638

A&A 446, 955-969 (2006)
DOI: 10.1051/0004-6361:20053638

II. HST-WFPC2 observations of two fields in the 30 Doradus region

M. Romaniello¹, S. Scuderi², N. Panagia³, R. M. Salerno⁴ and C. Blanco⁴

¹ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
    e-mail: mromanie@eso.org
² Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
    e-mail: scuderi@ct.astro.it
³ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
    e-mail: panagia@stsci.edu
⁴ Dipartimento di Fisica e Astronomia, Via S. Sofia 78, 95123 Catania, Italy

(Received 15 June 2005 / Accepted 4 October 2005)

Abstract
As a part of an ongoing effort to characterise the young stellar populations in the Large Magellanic Cloud, we present HST-WFPC2 broad and narrow band imaging of two fields with recent star formation activity in the Tarantula region. A population of objects with H $\alpha$ and/or Balmer continuum excess was identified. On account of the intense H $\alpha$ emission (equivalent widths up to several tens of Å), its correlation with the Balmer continuum excess and the stars' location on the HR diagram, we interpret them as low mass (~ $1{-}2~M_{\odot}$ ) Pre-Main Sequence stars. In this framework, the data show that coeval high and low mass stars have significantly different spatial distributions, implying that star formation processes for different ranges of stellar masses are rather different and/or require different initial conditions. We find that the overall slope of the mass function of the young population is somewhat steeper than the classical Salpeter value and that the star formation density of this young component is $0.2{-}0.4~M_{\odot}\,\mathrm{yr}^{-1}\,\mathrm{kpc}^{-2}$ , i.e. intermediate between the value for an active spiral disk and that of a starburst region. The uncertainties associated with the determination of the slope of the mass function and the star formation density are thoroughly discussed.

Key words: galaxies: evolution -- stars: fundamental parameters -- stars: formation -- stars: pre-main sequence -- stars: luminosity function, mass function -- Magellanic Clouds

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