We report the discovery of a new low-mass spectroscopic ( SB2 ) stellar binary system in the star-forming region of Upper Scorpius .
This object , UScoCTIOÂ 5 , was discovered by ( 1 ) , who assigned it a spectral class of M4 .
A Keck I HIRES spectrum revealed it to be double-lined , and we then carried out a program at several observatories to determine its orbit .
The orbital period is 34 days , and the eccentricity is nearly 0.3 .
The importance of such a discovery is that it can be used to help calibrate evolutionary models at low masses and young ages .
This is one of the outstanding problems in the study of formation mechanisms and initial mass functions at low masses .
The orbit allows us to place a lower limit of 0.64 \pm 0.02 M _ { \odot } on the total system mass .
The components appear to be of almost equal mass .
We are able to show that this mass is significantly higher than predicted by evolutionary models for an object of this luminosity and age , in agreement with other recent results .
More precise determination of the temperature and surface gravity of the components would be helpful in further solidifying this conclusion .