Free Astronomy Magazine July-August 2020

11 JULY-AUGUST 2020 EXOPLANETS mission, with reference to the motion in the space of the Proxima Centauri system. Another factor that makes the identifica- tion of the candidate planet uncertain in the SPHERE images is the excessive bright- ness of the signal. Previous theoretical stud- ies have fixed specific constraints on the mass, brightness and distance from the star for different planetary sizes, but the flux highlighted by Gratton’s team does not cor- respond to what the theoreticians fore- casted. According to some commentators, the latter inconsistency might be resolvable by assuming that the candidate planet is surrounded by a system of rings similar to those of Saturn. An alternative explanation could be a scenario like that of Fomalhaut b, where the excess in brightness is attribut- able to the destruction (partial or total) of a planet and the scattering of its fragments in an increasing volume of space. While the specialists were still arguing over the controversial existence of Proxima c, an article published last May 26 in Astronomy & Astrophysics brought Proxima b back again to the center of attention. In essence, the new work, carried out by a very crowded team of researchers led by Alejandro Suarez Mascareño (Instituto de Astrofísica de Ca- narias), has confirmed the existence of the first planet of Proxima Centauri, using the new and very powerful ESPRESSO spectro- graph installed on the ESO’s VLT. ESPRESSO was mostly designed and manu- factured in Switzerland by scientists and technicians from the University of Geneva, just like its predecessor HARPS. While the latter manages to measure oscillations of S ignal-to-noise maps of the Proxima Centauri system, acquired in 2018 by SPHERE and in which Gratton’s team sought evi- dence for Prox- ima c. The can- didate planet is the signal en- closed in small circles, but the uneven distribu- tion of the noise in the images makes identifica- tion uncertain. [R. Gratton et al.]