The planet orbiting the closest star to the sun, Proxima Centauri, could have a neighbor. An international team of astronomers with the participation of the Institute of Astrophysics of Andalusia, center of the Higher Council for Scientific Research (CSIC), has announced the discovery of what could be a second planet: Next c.
Proxima Centauri is a faint red star just 4.2 light years distant from Earth that is home to a potentially habitable planet, Proxima b (slightly more massive than Earth). According to the indications, this second planet would be much larger and farther from the star.
If it exists, Proxima c would be 5.8 times larger than Earth (or half the mass of Neptune) and would orbit its star approximately once every five Earth years (1.5 times the distance from the Sun) , according to the scientists comment in the journal Science Advances that publishes the study. Its temperature is approximately -200 C, if it does not have an atmosphere.
Could I have water?
Unfortunately, given the enormous distance that separates it from the star Proxima Centauri, the planet is also too cold to have liquid water , a key factor for habitability.
Super earth
Astronomers say they need new observations to confirm what is currently a clue as a planet. Also, considering its proximity, it is an ideal candidate for follow-up observations, and even imaging, with next-generation telescopes.
The discovery of the potential planet Proxima c is surprising, because its presence challenges current astronomical models of how super-earths form and evolve.
The discovery
The researchers analyzed “radial velocity” data collected over several years by the HARPS (High Precision Radial Velocity Planet Finder) and UVES (Echelle Ultraviolet and Visual Spectrograph) instruments, installed in telescopes operated by the European Southern Observatory (ESO). ) located in Chile. They tracked the light spectrum of Proxima Centauri over time, looking for regular oscillations that could indicate the presence of an undiscovered planet. This was not an easy job, as the combined measurements from the HARPS and UVES spectrographs spanned approximately 17.5 years.
The meticulous study bore fruit with the revelation of a possible planet, Proxima c, a super-earth whose confirmation would come from the hand of the European Space Agency’s Gaia spacecraft, according to experts.
In addition, scientists are considering searching for Proxima c through direct images, specifically from photographs captured by SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch), a tool installed on ESO’s Very Large Telescope in Chile. And the team’s data suggests the super-earth is probably there, waiting to be found -officially-. The detected signal is at the limit of the instrumental capabilities, so we hope that the astrometric data from the Gaia satellite will support the existence of Proxima c.
Referencia: M. Damasso et al. “A low-mass planet candidate orbiting Proxima Centauri at a distance of 1.5 au”. Science Advances, 2020. DOI: 10.1126/sciadv.aax7467
