  We present the results of a multiplicity survey of 212 T Tauri stars in the
Chamaeleon I and Taurus-Auriga star-forming regions, based on high-resolution
spectra from the Magellan Clay 6.5 m telescope. From these data, we achieved a
typical radial velocity precision of ~80 m/s with slower rotators yielding
better precision, in general. For 174 of these stars, we obtained multi-epoch
data with sufficient time baselines to identify binaries based on radial
velocity variations. We identified eight close binaries and four close triples,
of which three and two, respectively, are new discoveries. The spectroscopic
multiplicity fractions we find for Cha I (7%) and Tau-Aur (6%) are similar to
each other, and to the results of field star surveys in the same mass and
period regime. However, unlike the results from imaging surveys, the frequency
of systems with close companions in our sample is not seen to depend on primary
mass. Additionally, we do not find a strong correlation between accretion and
close multiplicity. This implies that close companions are not likely the main
source of the accretion shut down observed in weak-lined T Tauri stars. Our
results also suggest that sufficient radial velocity precision can be achieved
for at least a subset of slowly rotating young stars to search for hot Jupiter
planets.
