Thomas Preibisch, Thomas Stanke, Hans Zinnecker
Constraints on the IMF and the brown dwarf population of the young
cluster IC 348
Astronomy and Astrophysics, 409, 147-158 (2003)
We use a deep near-infrared census of the young stellar cluster IC~348
to construct and analyze its luminosity function.
Our mosaic image of IC 348 covers the full extent of the cluster
with a completeness limit of J ~ 19.5 and
is therefore sensitive for 2 Myr old cluster members with masses as low as
M >= 0.005 Msun for the mean extinction
of the known cluster members (Av ~ 3.5 mag).
By using information on stellar ages, extinctions, and the binary population
in IC 348 from several recent studies, we can derive statistical constraints
on the stellar and sub-stellar mass function of the cluster by
modeling the observed luminosity function.
We find that the stellar part
of the mass function in IC 348 is well described by the
galactic field star IMF. While several brown dwarfs have recently
been identified in IC 348, our data show that the cluster
harbors only a relatively small population of sub-stellar objects.
We find that brown dwarfs in the mass range 0.02-0.075 Msun
constitute at most ~10% of the total cluster population,
in contrast to recent results suggesting much larger brown dwarf
populations in other young clusters and also the galactic field.
Our results suggest that IC 348 has ~2 x fewer brown dwarfs
than the Orion Trapezium cluster.
A similar brown dwarf ``deficit'' was recently found in the Taurus star
We speculate about the possible causes for this result,
including the presence or absence of nearby massive stars and
their influence on the formation of low-mass young stellar objects.
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