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Sci Adv. 2020 Jan 15;6(3):eaax7467. doi: 10.1126/sciadv.aax7467. eCollection 2020 Jan.

A low-mass planet candidate orbiting Proxima Centauri at a distance of 1.5 AU.

Author information

1
INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
2
Department of Physics, University of Crete, Voutes, 70013 Heraklion, Greece.
3
Institute of Astrophysics, Foundation for Research and Technology-Hellas, PO Box 1527, 71110 Heraklion, Crete, Greece.
4
School of Physics and Astronomy, Queen Mary University of London, 327 Mile End Rd., E14NS London, UK.
5
Laboratoire Lagrange, UMR7293, Université Côte d'Azur, CNRS, Observatoire de la Côte d'Azur, Boulevard de l'Observatoire, 06304, Nice Cedex 4, France.
6
Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland.
7
Dipartimento di Fisica, Universitá degli Studi di Torino, Via Pietro Giuria 1, I-10125 Torino, Italy.
8
Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015-1305, USA.
9
Centre for Astrophysics Research School of Physics, Astronomy and Mathematics University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK.
10
American Association of Variable Stars Observers, 49 Bay State Road, Cambridge, MA 02138, USA.
11
Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile.
12
Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain.

Abstract

Our nearest neighbor, Proxima Centauri, hosts a temperate terrestrial planet. We detected in radial velocities evidence of a possible second planet with minimum mass m c sin i c = 5.8 ± 1.9M and orbital period P c = 5.21 - 0.22 + 0.26 years. The analysis of photometric data and spectro-scopic activity diagnostics does not explain the signal in terms of a stellar activity cycle, but follow-up is required in the coming years for confirming its planetary origin. We show that the existence of the planet can be ascertained, and its true mass can be determined with high accuracy, by combining Gaia astrometry and radial velocities. Proxima c could become a prime target for follow-up and characterization with next-generation direct imaging instrumentation due to the large maximum angular separation of ~1 arc second from the parent star. The candidate planet represents a challenge for the models of super-Earth formation and evolution.

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