A White Dwarf in Waiting: A Precursor Star with a Mysterious Massive Companion

Gautham Adamane Pallathadka and colleagues discovered SDSS J0229+7130, a proto-white dwarf orbiting an unseen, massive companion, likely a heavy white dwarf or neutron star. Using spectra, lightcurves, and models, they determined the system’s 36-hour orbit and ruled out a main-sequence companion. This rare binary likely formed through stable mass transfer and may evolve into a long-lived, compact pair emitting gravitational waves.