By analyzing 17 years of radial velocity data of Proxima Cen collected with the UVES and HARPS spectrographs, we detected a signal of period P 5 years that could be explained by the presence of a second planet, Proxima c, with minimum mass m sin i 6. Earth masses. Together with the low-mass temperate planet Proxima b, this candidate planet would make Proxima the closest multi-planet system to the Sun. We will present the properties of the new RV signal and investigate the likelihood that it is related to a magnetic activity cycle of the star. We will discuss how the existence of Proxima c can be confirmed, and its true mass determined with high accuracy, by combining Gaia astrometry and radial velocities. Proxima c would be a prime target for follow-up and characterization measurements, especially with next generation direct imaging instrumentation due to the large maximum angular separation of ̃1 arcsecond from the parent star. Since the orbit would be beyond the original location of the snowline, Proxima c would challenge the models of the formation of super-Earths. Presently, this study is under review by Science Advances.
AAS/Division for Extreme Solar Systems Abstracts
- Pub Date:
- August 2019