On the universal outcome of star-formation: Is there a link between stars and brown-dwarfs?

Abstract

(abridged) The recent evidence obtained by Briceno et al. that star-formation in Taurus-Auriga (TA) may be producing significantly fewer brown dwarfs (BDs) per star than the ONC is investigated by setting up a realistic model stellar plus BD population and explicitly taking into account a high binary proportion and dynamical evolution in the TA groups and the ONC. The Briceno result is reproduced almost exactly despite an identical IMF in both systems because many BD-BD and star-BD binaries are disrupted in the ONC thus freeing BDs, while the TA groups remain unevolved dynamically. However, the resulting populations do not have the correct star-star, star-BD and expecially BD-BD binary properties, even if a variable BD IMF is allowed for. The conclusion is therefore that BDs need to be added as a separate population which has its own binary properties. Such an extra population can have various origins which are briefly discussed in this contribution but more fully in an associated paper.

MNRAS, accepted, 23 pages, 14 figures, LaTeX, two references added

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