Sebastian Daemgen, Serge Correia, Monika G. Petr-Gotzens
We present a study of protoplanetary disks in spatially resolved low-mass
binary stars in the well-known Orion Nebula Cluster (ONC) in order to assess
the impact of binarity on the properties of circumstellar disks and its
relation to the cluster environment. This is the currently largest such study
in a clustered high stellar density star forming environment. We particularly
aim at determining the presence of magnetospheric accretion and dust disks for
each binary component, and at measuring the overall disk frequency. We carried
out spatially resolved Adaptive Optics assisted near-IR photometry and
spectroscopy of 26 binaries in the ONC, and determine stellar parameters such
as effective temperatures and spectral types, luminosities, masses, as well as
accretion properties and near-infrared excess for individual binary components.
A fraction of 40(+10/-9)% of the binary components in the sample can be
inferred to be T Tauri stars possesing an accretion disk. This is marginally
lower than the disk fraction of single stars of ~50% in the ONC. We find that
disks in wide binaries of >200AU separation are consistent with random pairing,
while the evolution of circumprimary and circumsecondary disks is observed to
be synchronized in closer binaries. Circumbinary disks appear to be not suited
to explain this difference. Further, we identify several mixed pairs of
accreting and non-accreting components, suggesting that these systems are
common, and without preference for the more or less massive component to evolve
faster. The derived mass accretion rates of the ONC binary components are of
similar magnitude as those for ONC single stars and for binaries in the Taurus
star forming region. The paper concludes with a discussion of the (presumably
weak) connection between the presence of inner accretion disks in young binary
systems and the existence of planets in stellar multiples.(abridged)
View original:
http://arxiv.org/abs/1201.2421
No comments:
Post a Comment