The young , low-mass , triple system NTTS 155808 - 2219 ( ScoPMS 20 ) was previously identified as a \sim 17-day period single-lined spectroscopic binary with a tertiary component at 0.21 arcseconds .
Using high-resolution infrared spectra , acquired with NIRSPEC on Keck II , both with and without adaptive optics , we measured radial velocities of all three components .
Reanalysis of the single-lined visible light observations , made from 1987 to 1993 , also yielded radial velocity detections of the three stars .
Combining visible light and infrared data to compute the orbital solution produces orbital parameters consistent with the single-lined solution and a mass ratio of q = 0.78 \pm 0.01 for the SB .
We discuss the consistency between our results and previously published data on this system , our radial-velocity analysis with both observed and synthetic templates , and the possibility that this system is eclipsing , providing a potential method for the determination of the stars ’ absolute masses .
Over the \sim 20 year baseline of our observations , we have measured the acceleration of the SB ’ s center-of-mass in its orbit with the tertiary .
Long-term , adaptive optics imaging of the tertiary will eventually yield dynamical data useful for component mass estimates .