A multiplanet system of super-Earths orbiting the brightest red dwarf star GJ 887

Jeffers, S. V.; Dreizler, S.; Barnes, J. R.; Haswell, C. A.; Nelson, R. P.; Rodríguez, E.; López-González, M. J.; Morales, N.; Luque, R.; Zechmeister, M.; Vogt, S. S.; Jenkins, J. S.; Palle, E.; Berdi ñas, Z. M.; Coleman, G. A. L.; Díaz, M. R.; Ribas, I.; Jones, H. R. A.; Butler, R. P.; Tinney, C. G.; Bailey, J.; Carter, B. D.; O’Toole, S.; Wittenmyer, R. A.; Crane, J. D.; Feng, F.; Shectman, S. A.; Teske, J.; Reiners, A.; Amado, P. J. and Anglada-Escudé, G. (2020). A multiplanet system of super-Earths orbiting the brightest red dwarf star GJ 887. Science, 368(6498) pp. 1477–1481.

DOI: https://doi.org/10.1126/science.aaz0795

Abstract

The closet exoplanets to the Sun provide opportunities for detailed characterization of planets outside the Solar System. We report the discovery, using radial velocity measurements, of a compact multiplanet system of super-Earth exoplanets orbiting the nearby red dwarf star GJ 887. The two planets have orbital periods of 9.3 and 21.8 days. Assuming an Earth-like albedo, the equilibrium temperature of the 21.8-day planet is ~350 kelvin. The planets are interior to, but close to the inner edge of, the liquid-water habitable zone. We also detect an unconfirmed signal with a period of ~50 days, which could correspond to a third super-Earth in a more temperate orbit. Our observations show that GJ 887 has photometric variability below 500 parts per million, which is unusually quiet for a red dwarf.