An international team of researchers, led by scientists from the Instituto de Astrofísica de Canarias (IAC), has just made public the discovery of two planets with a mass similar to Earth in orbit around the star GJ 1002, a red dwarf not too far from the Solar system. Both worlds are in the habitable zone of the star, that is, at the correct distance for liquid water to exist on their surfaces.
“Nature seems hell-bent on showing us that Earth-like planets are very common. With these two we already know 7 in planetary systems quite close to the Sun,” he explains. Alejandro Suarez Mascarenofrom the IAC and first signer of the article recently published in ‘Astronomy & Astrophysics’.
The two new planets, GJ 1002b and GJ 1002c, are about 16 light-years away. Both have masses very similar to that of our own world and the first, the innermost, takes 10 days to complete an orbit around its star, while the second, somewhat further from it, needs a little over 21 days.
«GJ 1002 -says for his part Vera Maria Passegger, also from the IAC and co-author of the study- is a red dwarf star, with barely one eighth of the mass of the Sun. It is a rather cold and dim star. This means that its habitable zone is very close to it.” The closeness of the two new worlds to our Solar System means that both, especially GJ 1002c, are excellent candidates for studying their atmospheres and finding out if their Earth-likeness goes ‘beyond’ mere physical features.
“The future ANDES spectrograph for the ESO ELT telescope in which the IAC participates -he says Jonay I. Gonzalez Hernandezco-author of the research – could capture the presence of oxygen in the atmosphere of GJ 1002c”.
“Due to its low temperature -explains for his part- Ignasi Ribas, a researcher at the Institute of Space Sciences (ICE-CSIC) and another of the co-authors of the article-, the visible light of GJ 1002 is too weak to measure its speed variations with most spectrographs«. For this reason, the researchers used two instruments, ESPRESSO and CARMENES, which observed the star between 2017 and 2019 and between 2019 and 2021, respectively.
the two instruments
CARMENES has a great sensitivity in a wide range of near-infrared wavelengths, superior to that of other spectrographs designed to detect variations in the speeds of stars, which allowed it to study GJ 1002 in detail from the 3.5 telescope. m from the Calar Alto observatory.
The combination with ESPRESSO, for its part, allowed measurements with an accuracy of only 30 cm/sec, something that cannot be achieved with any other instrument in the world. «Separately, assures Suarez Mascareño- either of the two groups would have had many difficulties if they had approached this work independently. But together we have been able to go much further.