CoRoT 101186644: A transiting low-mass dense M-dwarf on an eccentric 20.7-day period orbit around a late F-star - Discovered in the CoRoT lightcurves

摘要

We present the study of the CoRoT transiting planet candidate 101186644, also named LRc01_E1_4780. Analysis of the CoRoT lightcurve and the HARPS spectroscopic follow-up observations of this faint (mV?=?16) candidate revealed an eclipsing binary composed of a late F-type primary (Teff?=?6090?±?200?K) and a low-mass, dense late M-dwarf secondary on an eccentric (e?=?0.4) orbit with a period of ~20.7 days. The M-dwarf has a mass of 0.096?±?0.011?M⊙, and a radius of 0.104-0.006+0.026?R⊙, which possibly makes it the smallest and densest late M-dwarf reported so far. Unlike the claim that theoretical models predict radii that are 5–15% smaller than measured for low-mass stars, this one seems to have a radius that is consistent and might even be below the radius predicted by theoretical models.