Astronomers are now confident that there are two exoplanets orbiting Proxima Centauri, Earth’s nearest star located at around four light-years away. The confirmation comes after three independent studies managed to finally verify the second planet around Proxima B, raising hope that the not-so-distant star system may have at least one planet that meets the requirements for life as we know it to exist on its surface.
But the idea that Proxima Centauri could harbor a planet capable of sustaining life as we know it isn’t new. In fact, back in 2016, astronomers had already proposed the existence of an Earth-like planet around the Red Dwarf. The existence of Proxima b was actually confirmed not long ago thanks to the European Space Agency’s ESPRESSO instrument, which finally settles the dilemma whether the original detection of the exoplanet was an error.
Now, it turns out that not only is this exoplanet real, but there’s another one accompanying it in orbit around Proxima Centauri.
Proxima b is orbiting its host star in what is dubbed the habitable zone–an area around the star where temperatures are just right for liquid water to exist on the surface. But earlier this year, a group of astronomers revealed that there could be evidence of another world orbiting Proxima Centauri in a far more distant and colder orbit.
Led by astronomer Mario Damasso of Italy’s National Institute for Astrophysics (INAF), researchers hinted at the possibility of another world located around four light-years away.
The astronomer had gone through nearly eighteen years of data, studying the wobbling produced by Proxima Centauri, and whether this was caused by processes that could involve a planet or several planets orbiting it, or something within the star itself.
This study caught the attention of another scientist, a man called Dritz Benedict, who happens to be a Senior Research Scientist at the McDonald Observatory. Benedict reanalyzed data of the planetary system that was gathered around 20 years ago through Hubble Space Telescope.
It was Benedict, together with Barbara MacArthur, who analyzed the movement of Proxima Centauri across the sky using Hubble’s Fine Guidance Sensors (FGS) nearly three decades ago. At the time, the researchers were analyzing data that could point them towards the existence of a planet, but only with orbital periods of 1,000 days or less.
But what if there was a planet with an orbital period greater than 1,000 days? This hunch led Benedict to reanalyze the data. To his surprise, there was something there, a planet with an orbital period of 1,907 days, dubbed Proxima C, and it was hiding in plain sight, in data going back several decades.
The SPHERE instrument has allowed us to better understand the planet’s orbital path, and thanks to observations by the Very Large Telescope in Chile, we have growing evidence of the existence of the planet, which has helped us better understand what its like. The data astronomers have gathered to date tells us that Proxima C is real, and it has a mass around seven times that of Earth.