AGB stars in the Magellanic Clouds

Free access article

Issue		A&A Volume 448, Number 1, March II 2006


Page(s)		77 - 91
Section		Extragalactic astronomy
DOI		http://dx.doi.org/10.1051/0004-6361:20053933

A&A 448, 77-91 (2006)
DOI: 10.1051/0004-6361:20053933

II. The rate of star formation across the LMC

M.-R. L. Cioni¹, L. Girardi², P. Marigo³ and H. J. Habing⁴

¹ SUPA, School of Physics, University of Edinburgh, IfA, Blackford Hill, Edinburgh EH9 3HJ, UK
e-mail: mrc@roe.ac.uk
² Osservatorio Astronomico di Trieste, INAF, via G. B. Tiepolo 11, 34131 Trieste, Italy
³ Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 2, 35122 Padova, Italy
⁴ Sterrewacht Leiden, Niels Bohrweg 2, 2333 RA Leiden, The Netherlands

(Received 27 July 2005 / Accepted 29 September 2005)

Abstract
This article compares the distribution of $K_{\rm s}$ magnitudes of Large Magellanic Cloud (LMC) asymptotic giant branch (AGB) stars obtained from the DENIS and 2MASS data with theoretical distributions. These have been constructed using up-to-date stellar evolution calculations for low and intermediate-mass stars, and in particular for thermally pulsing AGB stars. A fit of the magnitude distribution of both carbon- and oxygen-rich AGB stars allowed us to constrain the metallicity distribution across the LMC and its star formation rate (SFR). The LMC stellar population is found to be on average 5-6 Gyr old and is consistent with a mean metallicity corresponding to Z=0.006. These values may however be affected by systematic errors in the underlying stellar models, and by the limited exploration of the possible SFR histories. Instead our method should be particularly useful for detecting variations in the mean metallicity and SFR across the LMC disk. There are well defined regions where both the metallicity and the mean-age of the underlying stellar population span the whole range of grid parameters. The C/M ratio discussed in Paper I is a tracer of the metallicity distribution if the underlying stellar population is older than about a few Gyr. A similar study across the Small Magellanic Cloud is given in Paper III of this series.

Key words: galaxies: Magellanic Clouds -- stars: late-type -- Galaxy: abundances -- stars: luminosity function, mass function

SIMBAD Objects

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.