Toward understanding the formation of multiple systems : a pilot
PdBI survey of Class~0 protostars
Anaëlle MAURY
ESO, Garching
Résumé :
The formation process of binary stars and multiple systems is
poorly understood. The multiplicity rate of Class II pre-main-sequence
stars and Class I protostars is well documented and known to be
high ($\sim$ 30\% to 50\% with separations comprised between
$\sim$ 100 and 4000 AU). However, optical/near-infrared observations
of Class I/Class II YSOs barely constrain the pristine properties
of multiple systems, since dynamical evolution can quickly alter
these properties during the protostellar phase. Seeking to determine
the typical outcome of protostellar collapse and constrain models
of binary formation by core fragmentation during collapse, we used
high-resolution millimeter continuum imaging of very young (Class 0)
protostars observed at the beginning of the main accretion phase.
I will present our recent 1.3 mm high-resolution PdBI observations of
nearby low-mass Class 0 objects that set, for the first time,
constraints on the structure and multiplicity rate on scales
$<$ 150 AU (typical of most PMS binaries) at the beginning of
protostellar evolution. Finally, thanks to detailed comparisons
with numerical simulations of protostellar formation, I will
show our PdBI observations of Class 0 objects favor the models
of magnetized collapse against the purely hydrodynamical ones.
