Bibcode
Weidner, C.; Kroupa, P.
Referencia bibliográfica
Starbursts: From 30 Doradus to Lyman Break Galaxies, Held in Cambridge, UK, 6-10 September 2004. Edited by R. de Grijs and R.M. González Delgado. Astrophysics & Space Science Library, Vol. 329. Dordrecht: Springer, 2005, p.P83
Advertised on:
5
2005
Número de citas
0
Número de citas referidas
0
Descripción
Observations indicate that young massive star clusters in spiral and
dwarf galaxies follow a relation between luminosity of the brightest
young cluster and the star-formation rate (SFR) of the host galaxy, in
the sense that higher SFRs lead to the formation of brighter clusters.
Assuming that the empirical relation between maximum cluster luminosity
and SFR reflects an underlying similar relation between maximum cluster
mass (Mecl,max) and SFR, we compare the resulting
SFR(Mecl,max) relation with different theoretical models. The
empirical correlation is found to suggest that individual star clusters
form on a free-fall time-scale with their pre-cluster
molecular-cloud-core radii typically being a few pc, independent of
mass. The cloud cores contract by factors of 5 to 10 while building up
the embedded cluster. A theoretical SFR(Mecl,max) relation in
very good agreement with the empirical correlation is obtained if the
cluster mass function of a young population has a Salpeter exponent
β = 2.35 and if this cluster population forms within a
characteristic time-scale of a few × 10 Myr. This short time-scale
can be understood if the interstellar medium is pressurised, thus
precipitating rapid local fragmentation and collapse on a galactic
scale. Such triggered star formation on a galactic scale is observed to
occur in interacting galaxies. With a global SFR of 3-5
M&sun; yr-1, the Milky Way appears to lie on the
empirical SFR(Mecl,max) relation, given the recent detections
of very young clusters with masses near 105
M&sun; in the Galactic disk. The observed properties of the
stellar population of very massive young clusters suggests that there
may exist a fundamental maximum cluster mass, 106 <
Mecl,max*/M&sun; < 107.