SCYON Abstract

Received on August 21 2008

A discontinuity in the low-mass IMF - the case of high multiplicity

AuthorsIngo Thies and Pavel Kroupa
AffiliationArgelander-Institut für Astronomie, Bonn
Accepted byMonthly Notices of the Royal Astronomical Society
Contactithies@astro.uni-bonn.de
URLhttp://arxiv.org/abs/0808.2644
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Abstract

The empirical binary properties of brown dwarfs (BDs) differ from those of normal stars suggesting BDs form a separate population. Recent work by Thies and Kroupa revealed a discontinuity of the initial mass function (IMF) in the very-low-mass star regime under the assumption of a low multiplicity of BDs of about 15 per cent. However, previous observations had suggested that the multiplicity of BDs may be significantly higher, up to 45 per cent. This contribution investigates the implication of a high BD multiplicity on the appearance of the IMF for the Orion Nebula Cluster, Taurus-Auriga, IC 348 and the Pleiades. We show that the discontinuity remains pronounced even if the observed MF appears to be continuous, even for a BD binary fraction as high as 60%. We find no evidence for a variation of the BD IMF with star-forming conditions. The BD IMF has a power-law index αBD ≈ +0.3 and about 2 BDs form per 10 low-mass stars assuming equal-mass pairing of BDs.