Issue |
A&A
Volume 448, Number 3, March IV 2006
|
|
---|---|---|
Page(s) | 1007 - 1022 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20053836 | |
Published online | 03 March 2006 |
The IMF and star formation history of the stellar clusters in the Vela D cloud
1
INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy e-mail: fmassi@arcetri.astro.it
2
ESO, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19, Chile
Received:
15
July
2005
Accepted:
8
November
2005
Aims.We present the results of a Near-Infrared deep photometric survey of a
sample of six embedded star clusters in the Vela-D molecular cloud,
all associated with luminous (
) IRAS
sources. The clusters are unlikely to be older than a few 106
yrs, since all are still associated with molecular gas.Methods.We employed the fact that all clusters lie at the same distance and
were observed with the same instrumental setting to derive
their properties in a consistent way, being affected by the same
instrumental and observational biases.
We extracted the clusters' K Luminosity Functions and developed a
simple method to correct them for extinction, based on colour-magnitude
diagrams. The reliability of the method has been tested by
constructing synthetic clusters from theoretical tracks for pre-main
sequence stars and a standard Initial Mass Function.
The clusters' Initial Mass Functions have been derived from the
dereddened
K Luminosity Functions by adopting a set of pre-main sequence
evolutionary tracks and assuming coeval star formation.Results.All clusters are small (
members) and compact (radius
pc); their most massive stars are
intermediate-mass (
) ones.
The dereddened K Luminosity Functions are likely to arise
from the same
distribution, suggesting that the selected clusters have quite
similar Initial Mass Functions and star formation histories.
The Initial Mass Functions are consistent with those
derived for field stars and clusters. Adding them
together we found that the “global” Initial Mass Function
appears steeper at the high-mass end and
exhibits a drop-off at
. In fact,
a standard Initial Mass Function would
predict a star with
within one of the clusters,
which is not found. Hence, either high-mass stars need larger
clusters
to be formed, or the Initial Mass Function of the single clusters is
steeper at the
high-mass end because of the physical conditions in the parental gas.
© ESO, 2006
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