TY - JOUR
T1 - A 'super' star cluster grown old
T2 - the most massive star cluster in the Local Group
AU - Ma, J.
AU - de Grijs, R.
AU - Yang, Y.
AU - Zhou, X.
AU - Chen, J.
AU - Jiang, Z.
AU - Wu, Z.
AU - Wu, J.
PY - 2006/5/21
Y1 - 2006/5/21
N2 - We independently redetermine the reddening and age of the globular cluster (GC) 037-B327 in M31 by comparing independently obtained multicolour photometry with theoretical stellar population synthesis models. 037-B327 has long been known to have a very large reddening value, which we confirm to be E(B -V) = 1.360 ± 0.013, in good agreement with the previous results. We redetermine its most likely age at 12.4 ± 3.2 Gyr. 037-B327 is a prime example of an unusually bright early counterpart to the ubiquitous 'super' star clusters presently observed in most high-intensity star-forming regions in the local Universe. In order to have survived for a Hubble time, we conclude that its stellar initial mass function (IMF) cannot have been top-heavy. Using this constraint, and a variety of simple stellar population (SSP) models, we determine a photometric mass of MGC = (3.0±0.5) × 107 M⊙, somewhat depending on the SSP models used, the metallicity and age adopted and the IMF representation. This mass, and its relatively small uncertainties, makes this object the most massive star cluster of any age in the Local Group. Assuming that the photometric mass estimate thus derived is fairly close to its dynamical mass, we predict that this GC has a (onedimensional) velocity dispersion of the order of (72 ± 13) km s -1. As a surviving 'super' star cluster, this object is of prime importance for theories aimed at describing massive star cluster evolution.
AB - We independently redetermine the reddening and age of the globular cluster (GC) 037-B327 in M31 by comparing independently obtained multicolour photometry with theoretical stellar population synthesis models. 037-B327 has long been known to have a very large reddening value, which we confirm to be E(B -V) = 1.360 ± 0.013, in good agreement with the previous results. We redetermine its most likely age at 12.4 ± 3.2 Gyr. 037-B327 is a prime example of an unusually bright early counterpart to the ubiquitous 'super' star clusters presently observed in most high-intensity star-forming regions in the local Universe. In order to have survived for a Hubble time, we conclude that its stellar initial mass function (IMF) cannot have been top-heavy. Using this constraint, and a variety of simple stellar population (SSP) models, we determine a photometric mass of MGC = (3.0±0.5) × 107 M⊙, somewhat depending on the SSP models used, the metallicity and age adopted and the IMF representation. This mass, and its relatively small uncertainties, makes this object the most massive star cluster of any age in the Local Group. Assuming that the photometric mass estimate thus derived is fairly close to its dynamical mass, we predict that this GC has a (onedimensional) velocity dispersion of the order of (72 ± 13) km s -1. As a surviving 'super' star cluster, this object is of prime importance for theories aimed at describing massive star cluster evolution.
KW - globular clusters: individual: 037-B327
KW - galaxies: individual: M31
KW - galaxies: star clusters
UR - http://www.scopus.com/inward/record.url?scp=33646468086&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2966.2006.10231.x
DO - 10.1111/j.1365-2966.2006.10231.x
M3 - Article
AN - SCOPUS:33646468086
SN - 0035-8711
VL - 368
SP - 1443
EP - 1450
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -