An ablating 2.6 M planet in an eccentric binary from the Dispersed Matter Planet Project

Barnes, John R,; Haswell, Carole A.; Staab, Daniel; Anglada-Escudé, Guillem; Fossati, Luca; Doherty, James P. J.; Cooper, Joseph; Jenkins, James S.; Díaz, Matías R.; Soto, Maritza G. and Peña Rojas, Pablo A. (2020). An ablating 2.6 M planet in an eccentric binary from the Dispersed Matter Planet Project. Nature Astronomy, 4(4) pp. 419–426.



Earth-mass exoplanets are difficult to detect. The Dispersed Matter Planet Project (DMPP) identifies stars that are likely to host the most detectable low-mass exoplanets. The star DMPP-3 (HD 42936) shows signs of circumstellar absorption, indicative of mass loss from ablating planets. Here, we report the radial velocity discovery of a highly eccentric 507 d binary companion and a hot super-Earth-mass planet in a 6.67 d orbit around the primary star. DMPP-3A is a solar-type star while DMPP-3B is just massive enough to fuse hydrogen. The binary, with semi-major axis 1.22 ± 0.02 au, is considerably tighter than others known to host planets orbiting only one of the component stars. The configuration of the DMPP-3 planetary system is rare and indicates dynamical interactions, though the evolutionary history is not entirely clear. DMPP-3A b is possibly the residual core of a giant planet precursor, consistent with the inferred circumstellar gas shroud.

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