White dwarfs are the burnt-out cores of Sun-like stars and are the fate of 97 per cent of the stars in our Galaxy. The internal structure and composition of white dwarfs are hidden by their high gravities, which causes all elements apart from the lightest ones to settle out of their atmospheres. The most direct method of probing the inner structure of stars and white dwarfs in detail is via asteroseismology. Here we present a pulsating white dwarf in an eclipsing binary system, enabling us to place extremely precise constraints on the mass and radius of the white dwarf from the lightcurve, independent of the pulsations. This 0.325-solar-mass white dwarf—one member of the SDSS J115219.99+024814.4 system—will serve as a powerful benchmark with which to constrain empirically the core composition of low-mass stellar remnants and to investigate the effects of close binary evolution on the internal structure of white dwarfs.

白矮星是太阳般恒星的枯竭核心，是银河系97％恒星的命运。白矮星的内部结构和成分被其高重力所掩盖，这使除最轻的矮星外的所有元素都脱离了大气。详细探测恒星和白矮星内部结构的最直接方法是通过星震学。在这里，我们在日食二元系统中给出了一个脉动的白矮星，这使我们能够对光曲线中白矮星的质量和半径施加极其精确的约束，而与脉动无关。这个0.325太阳质量的白矮星-SDSS J115219.99 + 024814的成员之一。