The ESPRESSO spectrograph confirmed the existence of earth-like exoplanets b Proxima the nearest star to the Sun. Additional observations made by the tool, allowed us to determine its mass, and also register a second signal, which theoretically can be explained by the presence of another planet. Article accepted for publication in Astronomy & Astrophysics, Preprint available at arXiv.org.
In 2016, astronomers reported the discovery of a planet around the red dwarf Proxima Centauri, the nearest star to Earth, located about 4.2 light years from Earth. Celestial body rotates around the star with a period of 11.2 days and is in the habitable zone — that is, the conditions at the surface allow the existence of liquid water (more in the article “it is Impossible to be closer”). The discovery of Proxima b has become one of the most important milestones in exoplanetary astronomy in recent years, but the limited accuracy of available measurements of radial velocity and the complexity of the modelling required the confirmation of the existence of earth-like planets.
An international team of astronomers used a spectrograph, a new generation of ESPRESSO, working in the complex VLT to measure the radial velocity of the star with an accuracy of 30 centimeters per second. The data obtained was three times more accurate than the HARPS spectrograph instrument of the same type, but of the previous generation, with which the discovery was made. Combining observations of ESPRESSO together with the previous measurements showed that the mass of Proxima b is not less than 1,17 earth, which is less than the previous estimate of 1.27 land masses.
In addition, scientists have recorded an additional signal that is repeated with a period of 5.5 days, which is what they failed to explain. Hypothetically it might come from the second planet: if the assumption is true, then its minimum weight is less than a third of the earth, and it is situated at a distance of 0.03 astronomical units from Proxima Centauri (one astronomical unit equals the average distance from the Earth to the Sun).
In the past researchers have suspected the existence of another planet in the system — this time super-earths, a year which lasts about five years. It is more massive than the Earth five and one-half times and may have a ring similar to Saturn’s rings, but this discovery has not yet been confirmed.