RX J0513.1 + 0851 and RX J0539.9 + 0956 were previously identified as young , low-mass , single-lined spectroscopic binary systems and classified as weak-lined T Tauri stars at visible wavelengths .
Here we present radial velocities , spectral types , v \sin i values , and flux ratios for the components in these systems resulting from two-dimensional cross-correlation analysis .
These results are based on high-resolution , near-infrared spectroscopy taken with the Keck II telescope to provide a first characterization of these systems as double-lined rather than single-lined .
It applies the power of infrared spectroscopy to the detection of cool secondaries ; the flux scales as a less steep function of mass in the infrared than in the visible , thus enabling an identification of low-mass secondaries .
We found that the RX J0513.1 + 0851 and RX J0539.9 + 0956 primary stars are fast rotators , 60 km s ^ { -1 } and 80 km s ^ { -1 } respectively ; this introduces extra difficulty in the detection of the secondary component as a result of the quite broad absorption lines .
To date , these are the highest rotational velocities measured for a pre-main sequence spectroscopic binary .
The orbital parameters and mass ratios were determined by combining new visible light spectroscopy with our infrared data for both systems .
For RX J0513.1 + 0851 , we derived a period of \sim 4 days and a mass ratio of q = 0.46 \pm 0.01 and for RX J0539.9 + 0956 , a period of \sim 1117 days and a mass ratio of q = 0.66 \pm 0.01 .
Based on our derived properties for the stellar components , we estimate the luminosities and hence distances to these binaries at 220 pc and 90 pc .
They appear to be significantly closer than previously estimated .