A Very Low Mass Star Transiting its Host Star

The low mass and intrinsic faintness of red dwarf stars make these objects difficult to study. As a consequence, the mass-radius relationship is poorly known for red dwarf stars. This is especially so for very low mass stars (VLMS) (i.e. stars with less than 10 percent the mass of the Sun). J2343+29A is a star with ~0.864 times the mass and ~0.854 times the radius of the Sun. The star's effective temperature is 5125 ± 67 K. Observations of J2343+29A show that it has a transiting companion in a 16.953 day orbit around it. Transit and radial velocity observations show that the companion is a VLMS with 0.098 ± 0.007 times the mass and 0.127 ± 0.007 times the radius of the Sun. With its mass and radius well constrained, the companion of J2343+29A is potentially a good benchmark for the study of VLMS.

Reference:
Chaturvedi et al. (2016), "Detection of a very low mass star in an Eclipsing Binary system", arXiv:1607.03277 [astro-ph.SR]