P. Viana Almeida, C. Melo, N. C. Santos, P. Figueira, M. Sterzik, J. F. Gameiro
The formation of spectroscopic binaries (SB) may be a natural byproduct of
star formation. The early dynamical evolution of multiple stellar systems after
the initial fragmentation of molecular clouds leaves characteristic imprints on
the properties of young, multiple stars. The discovery and the characterization
of the youngest SB will allow us to infer the mechanisms and timescales
involved in their formation. Our work aims to find spectroscopic companions
around young stellar objects (YSO). We present a near-IR high-resolution (R ~
60000) multi-epoch radial velocity survey of 7 YSO in the star forming region
(SFR) rho-Ophiuchus. The radial velocities of each source were derived using a
two-dimensional cross-correlation function, using the zero-point established by
the Earth's atmosphere as reference. More than 14 spectral lines in the CO
(0-2) bandhead window were used in the cross-correlation against LTE
atmospheric models to compute the final results. We found that the spectra of
the protostars in our sample agree well with the predicted stellar photospheric
profiles, indicating that the radial velocities derived are indeed of stellar
nature. Three of the targets analyzed exhibit large radial velocity variations
during the three observation epochs. These objects - pending further
confirmation and orbital characteristics - may become the first evidence for
proto-spectroscopic binaries, and will provide important constraints on their
formation. Our preliminary binary fraction (BF) of ~71% (when merging our
results with those of previous studies) is in line with the notion that
multiplicity is very high at young ages and therefore a byproduct of star
formation
View original:
http://arxiv.org/abs/1112.6341
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