The formation of low-mass helium white dwarfs in close binaries
  Recently, a large number of low-mass (<0.30 M_sun) helium white dwarfs (He WDs) have been discovered as a result of several surveys campaigns such as WASP, ELM, Kepler or SDSS. The far majority of them have as companion another compact object. There appears to be discrepancies between current theoretical modelling of low-mass He WDs and a number of key observational cases indicating that some details of their formation scenario yet remain to be understood. 
Alina G. Istrate
astro-ph.SR astro-ph.HE