Data Confirms Exoplanet Proxima Centauri c
McDonald Observatory | University of Texas | 2020 Jun 02
Fritz Benedict has used data he took over two decades ago with Hubble Space Telescope to confirm the existence of another planet around the Sun’s nearest neighbor, Proxima Centauri, and to pin down the planet’s orbit and mass. ...
Proxima Centauri has been in the news frequently since 2016, when scientists including McDonald Observatory’s Michael Endl found its first planet, Proxima Centauri b. The discovery incited speculation on the types of in-depth studies that could done on an extrasolar planet so close to our own solar system.
Adding to the excitement, earlier this year a group led by Mario Damasso of Italy’s National Institute for Astrophysics (INAF) announced they might have found another planet orbiting Proxima Centauri farther out. This group used radial velocity observations, that is, measurements of the star’s motion on the sky toward and away from Earth, to deduce the possible planet (dubbed Proxima Centauri c) orbits the star every 1,907 days at distance of 1.5 AU (that is, 1.5 times the distance at which Earth orbits the Sun). ...
Still, the existence of planet c was far from certain. Thus Benedict decided to re-visit his studies of Proxima Centauri from the 1990s made with Hubble Space Telescope. For that study, he had used Hubble’s Fine Guidance Sensors (FGS). ... In this case, he used FGS to search for Proxima Centauri’s motion on sky caused by tugging from its surrounding — and unseen — planets. ...
Indeed, Benedict found a planet with an orbital period of about 1,907 days buried in the 25-year-old Hubble data. This was an independent confirmation of the existence of Proxima Centauri c. ...