The measurement is a slight refinement on that made by HARPS, as the earlier spectrograph had placed Proxima b’s mass at around 1.3 Earth masses.
ESPRESSO carried out measurements of Proxima Centauri’s radial velocity with a stunning accuracy of 30 cm/s, which is about three times more precise than the measurements of HARPS.
These measurements were followed up by the more sophisticated ESPRESSO instrument, currently the most powerful spectrograph on Earth — designed by the same team from Geneva, and essentially HARPS’ successor.
Proxima b, an exoplanet orbiting a red dwarf star, was initially detected four years ago by an older spectrograph, HARPS, as a disturbance in the star’s orbit, which suggested the presence of another body.
Proxima b an Earth-like exoplanet orbiting in the habitable zone of the nearest star to our own in the Proxima Centauri solar system — located just 4.2 light-years from Earth — has been confirmed by an international team of astronomers from the University of Geneva.