2 research outputs found
IN-SYNC. VII. Evidence for a decreasing spectroscopic binary fraction from 1 to 100 Myr within the IN-SYNC sample
We study the occurrence of spectroscopic binaries in young star-forming
regions using the INfrared Spectroscopy of Young Nebulous Clusters(IN-SYNC)
survey, carried out in SDSS-III with the APOGEE spectrograph. Multi-epoch
observations of thousands of low-mass stars in Orion A, NGC 2264, NGC 1333, IC
348, and the Pleiades have been carried out, yielding H-band spectra with a
nominal resolution of R=22,500 for sources with H 12 mag. Radial velocity
precisions of 0.3 were achieved, which we use to identify
radial velocity variations indicative of undetected companions. We use Monte
Carlo simulations to assess the types of spectroscopic binaries to which we are
sensitive, finding sensitivity to binaries with orbital periods d,
for stars with and 100 . Using Bayesian inference, we find evidence
for a decline in the spectroscopic binary fraction, by a factor of 3-4 from the
age of our pre-main-sequence sample to the Pleiades age . The significance of
this decline is weakened if spot-induced radial-velocity jitter is strong in
the sample, and is only marginally significant when comparing any one of the
pre-main-sequence clusters against the Pleiades. However, the same decline in
both sense and magnitude is found for each of the five pre-main-sequence
clusters, and the decline reaches statistical significance of greater than 95%
confidence when considering the pre-main-sequence clusters jointly. Our results
suggest that dynamical processes disrupt the widest spectroscopic binaries
( d) as clusters age, indicating that this
occurs early in the stars' evolution, while they still reside within their
nascent clusters.Comment: 21 pages, 9 Figure