New observations of Proxima Centauri, the nearest star to the Solar System, located at a distance of 4.2 light years, have made it possible to reveal the presence of a candidate low-mass planet orbiting the star at a distance 1.5 times greater than that separating the Earth from the Sun.

The discovery, published in the journal “Science Advances”, was made by an international team of researchers led by Mario Damasso. Professor Grzegorz Pojmański from the Astronomical Observatory of the University of Warsaw was a member of the team.

A new planet manifested itself by a tiny, 1,2 m/s changes of the stars’ radial velocity, measured with the spectrographs HARPS and UVES at the European Southern Observatory in Chile.

For the purpose of verification long term photometric observations obtained by the ASAS project, led by professor Pojmański since 1997, were used. ASAS data clearly show brightness changes due to rotation and chromospheric activity of the star. However, the time scales of these changes differ from the orbital period determined from the spectroscopic measurements.

The planet, named Proxima c, is almost 6 times more massive than the Earth and orbits its central star once in 5 years at a distance of 220 mln km. Since Proxima Centauri is a cool star (surface temperature of 3300 Celsius) its second planet warms up only to -230 Celsius.

Scientific team expects that the final verification of the existence of Proxima c will be possible using astrometric observations carried out by the Gaia space observatory.

The first planet of Proxima Centauri was discovered in 2016 by another team of astronomers including dr hab. Marcin Kirga from the Astronomical Observatory of the University of Warsaw.