Unconfirmed rumors have appeared of a Earth-sized planet orbiting Proxima Centauri, the nearest star to the Sun, within the habitable zone. The story first appeared in the German weekly Der Spiegel, but so far the source remains anonymous.
Der Spiegel credits the discovery to the European Southern Observatory (ESO), and claims the official announcement will come “at the end of August”. However, when contacted by AFP, ESO spokesman Richard Hook said: “We are not making any comment.”
In October 2012, to widespread fanfare, the ESO announced the existence of Alpha Centauri Bb, which would have set a record for the closest planet outside the Solar System. Sadly, however, subsequent evidence led to the claim’s retraction. Understandably, this may have made the ESO particularly anxious to protect their high reputation by not making another unsubstantiated claim on a closely related topic. If the report is indeed true, the delay could represent a desire to triple-check the findings for errors before making an announcement.
Even Der Spiegel’s anonymous source said: “We were working at the limit of technically feasible measurement.”
The silence from the ESO means that, even if the planet exists, the public will have to wait to learn how similar the planet is to Earth in mass. Likewise, it is unclear whether it lies in the heart of the habitable zone, or at the edges, where conditions are more tenuous. Even at the best possible location, Proxima’s tendency for large flares would endanger prospects for life.
Proxima Centauri is an M-type red dwarf that, at a distance of 4.2 light-years, is currently our nearest neighbor beyond the Sun. Its 500,000-plus-year orbit around Alpha Centauri A and B will see its parental stars usurp it as the closest star in about 27,000 years.
Despite its closeness, Proxima is too faint to be seen even with a small telescope, and has been figuratively overshadowed in the public imagination by the Sun-like stars it circles. Indeed, the most recent work to appear relating Proxima Centauri to planets was on whether its small gravity might have affected planetary formation around the stars it orbits. Nevertheless, as we have found planets, including rocky, terrestrial-type objects around other M dwarfs, attention has turned to Proxima itself. A recent study calculated the distance a planet would need to be from Proxima to be habitable, while others reported efforts to find such planets.
In April a project was announced to send a spacecraft to Alpha Centauri within 20 years of launch. If the rumors are true, the tiny neighboring star first discovered 101 years ago may be an even more enticing target.