SDSSJ1156-0207: A 0.54 M_sun + 0.19 M_sun Double-lined M Dwarf Eclipsing
  Binary System
  Eclipsing binaries are instrumental to our understanding of fundamental
stellar parameters. With the arrival of ultra-wide cameras and large area
photometric monitoring programs, numerous eclipsing binaries systems have been
reported photometrically. However, due to the expensive efforts to follow up
them spectroscopically, most of their basic properties remain unexplored. In
this paper we exploited the eclipsing binary light curves delivered by the
all-sky Catalina sky surveys, in tandem with the single shot spectroscopic
survey from SDSS, and identify a double-lined M-dwarf eclipsing binary
SDSSJ1156-0207. Because this system is very faint (V=15.89 mag), we obtained
follow-up radial velocity measurements using Gemini Multi-Object Spectrograph
onboard Gemini north telescope. This provides us a spectral resolution R~4000,
enabling us to determine the mass and radius of each stellar components when
jointly fitted with light curve. Our best-fit results indicate that both
components are of M dwarf, with the primary component to be 0.54+/-0.20 M_sun
and 0.46+/-0.08 R_sun, while the secondary component to be 0.19+/-0.08 M_sun
and 0.30+/-0.08 R_sun. High resolution spectroscopic observations in the future
will help pin down the stellar parameters, providing insights to the stellar
models at low mass regimes, as well as shedding lights on the internal
structure of close-in low mass objects and their inflation mechanism.
