We report the discovery of three stars that , along with the prototype LP 40 - 365 , form a distinct class of chemically peculiar runaway stars that are the survivors of thermonuclear explosions .
Spectroscopy of the four confirmed LP 40 - 365 stars finds ONe-dominated atmospheres enriched with remarkably similar amounts of nuclear ashes of partial O- and Si-burning .
Kinematic evidence is consistent with ejection from a binary supernova progenitor ; at least two stars have rest-frame velocities indicating they are unbound to the Galaxy .
With masses and radii ranging between 0.20–0.28 M _ { \sun } and 0.16–0.60 R _ { \sun } , respectively , we speculate these inflated white dwarfs are the partly burnt remnants of either peculiar Type Iax or electron-capture supernovae .
Adopting supernova rates from the literature , we estimate that \sim 20 LP 40 - 365 stars brighter than 19 mag should be detectable within 2 kpc from the Sun at the end of the Gaia mission .
We suggest that as they cool , these stars will evolve in their spectroscopic appearance , and eventually become peculiar O-rich white dwarfs .
Finally , we stress that the discovery of new LP 40 - 365 stars will be useful to further constrain their evolution , supplying key boundary conditions to the modelling of explosion mechanisms , supernova rates , and nucleosynthetic yields of peculiar thermonuclear explosions .