A Study of the Luminosity and Mass Functions of the Young IC 348 Cluster Using FLAMINGOS Wide-Field Near-Infrared Images

A. A. Muench, E. A. Lada, C. J. Lada, R. J. Elston, J. F. Alves, M. Horrobin, T. H. Huard, J. L. Levine, S. N. Raines, C. Román-Zúñiga

We present wide-field near-infrared (JHK) images of the young, τ=2

Myr IC 348 cluster taken with FLAMINGOS. We use these new data to

construct an infrared census of sources, which is sensitive enough to

detect a 10 MJup brown dwarf seen through an extinction of

AV~7. We examine the cluster's structure and relationship to

the molecular cloud and to construct the cluster's K-band luminosity

function. Using our model luminosity function algorithm, we derive the

cluster's initial mass function (IMF) throughout the stellar and

substellar regimes and find that the IC 348 IMF is very similar to that

found for the Trapezium cluster, with both cluster IMFs having a mode

between 0.2-0.08 Msolar. In particular, we find that, similar

to our results for the Trapezium, brown dwarfs constitute only one in

four of the sources in the IC 348 cluster. We show that a modest

secondary peak forms in the substellar IC 348 K-band luminosity function

(KLF), corresponding to the same mass range responsible for a similar

KLF peak found in the Trapezium. We interpret this KLF peak as either

evidence for a corresponding secondary IMF peak at the deuterium burning

limit or as arising from a feature in the substellar mass-luminosity

relation that is not predicted by current theoretical models. Finally,

we find that IC 348 displays radial variations of its subsolar (0.5-0.08

Msolar) IMF on a parsec scale. Whatever mechanism that is

breaking the universality of the IMF on small spatial scales in IC 348

does not appear to be acting on the brown dwarf population, whose

relative size does not vary with distance from the cluster center.

Department of Astrophysics
External organisation(s)
Harvard-Smithsonian Center for Astrophysics, University of Florida, Gainesville, Kitt Peak National Observatory, California Institute of Technology (Caltech)
The Astronomical Journal
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Peer reviewed
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