Vennes, StephaneNemeth, P.Kawka, AdelaThorstensen, John RKhalack, V.Ferrario, LiliaAlper, E H2020-12-202020-12-200036-8075http://hdl.handle.net/1885/217843Subluminous Type Ia supernovae, such as the Type Iax–class prototype SN 2002cx, are described by a variety of models such as the failed detonation and partial deflagration of an accreting carbon-oxygen white dwarf star or the explosion of an accreting, hybrid carbon-oxygen-neon core. These models predict that bound remnants survive such events with, according to some simulations, a high kick velocity. We report the discovery of a high proper motion, low-mass white dwarf (LP 40-365) that travels at a velocity greater than the Galactic escape velocity and whose peculiar atmosphere is dominated by intermediate-mass elements. Strong evidence indicates that this partially burnt remnant was ejected following a subluminous Type Ia supernova event. This supports the viability of single-degenerate supernova progenitors.application/pdfen-AU201710.1126/science.aam83782020-11-23