Issue |
A&A
Volume 449, Number 1, April I 2006
|
|
---|---|---|
Page(s) | 143 - 149 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20054157 | |
Published online | 16 March 2006 |
Age estimations of M 31 globular clusters from their spectral energy distributions
1
National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, PR China
2
Department of Physics and Astronomy, Box 871504, Arizona State University, Tempe, AZ 85287–1504, USA e-mail: majun@vega.bac.pku.edu.cn
Received:
6
September
2005
Accepted:
15
November
2005
This paper presents accurate spectral energy
distributions (SEDs) of 15 M 31 globular clusters (GCs) confirmed
by spectroscopy and/or high spatial-resolution imaging, as well as
30 M 31 globular cluster candidates detected by Mochejska et al. (1998, AcA, 48, 455).
Most of these candidates have , deeper than previous
searches, and these candidates have not yet been confirmed to be
globular clusters. The SEDs of these clusters and candidates are
obtained as part of the BATC Multicolor Survey of the Sky, in
which the spectrophotometrically-calibrated CCD images of M 31 in
13 intermediate-band filters from 4000 to 10 000 Å were
observed. These filters are specifically designed to exclude most
of the bright and variable night-sky emission lines including the
OH forest. In comparison to the SEDs of true GCs, we find that
some of the candidate objects are not GCs in M 31. SED fits show
that theoretical simple stellar population (SSP) models can fit
the true GCs very well. We estimate the ages of these GCs by
comparing with SSP models. We find that, the M 31 clusters range in
age from a few ten Myr to a few Gyr old, as well as old GCs,
confirming the conclusion that has been found by Barmby et al. (2000, AJ, 119, 727),
Williams & Hodge (2001, ApJ, 548, 190), Beasley et al. (2004, AJ, 128, 1623), Burstein et al.
(2004, ApJ, 614, 158) and Puzia et al. (2005, A&A, 434, 909) in their investigations of the
SEDs of M 31 globular clusters.
Key words: galaxies: individual: M 31 / galaxies: star clusters / galaxies: evolution
© ESO, 2006
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