Free Astronomy Magazine November-December 2022

43 NOVEMBER-DECEMBER 2022 ASTRO PUBLISHING planations involve a giant impact which removed part of the planet’s mantle or, because Mercury is the hottest planet, its high temperature could have evaporated part of its mantle. The discovery of other dense, Mercury-like planets around other stars is key to understanding the formation of such objects. In fact, the discovery of two super- Mercuries in the same planetary system, instead of one, offers scien- tists a revealing picture. “For the first time, using the ESPRESSO spec- trograph, we have discovered a sys- tem with two super-Mercuries. This helps us to understand how these planets were formed,” says Alejan- dro Suárez, researcher at the IAC and co-author of this study. “The possibility of a large impact to cre- ate a super-Mercury is already very unlikely, two giant impacts in the same system seems very improba- ble.” “Understanding how these two super-Mercuries have formed will require further characterization of the composition of these planets,” comments Jonay González, re- searcher at the IAC co-author of this study. “The future Extremely Large Telescope (ELT) and its first genera- tion high resolution spectrograph ANDES, will provide for the first time both the required sensitivity and precision to probe the compo- sition of their surface, or the exis- tence and composition of a po- tential atmosphere.” For the team, this is just a first step towards their ultimate goal: finding another Earth. “The existence of an atmosphere would give us insight into the formation and evolution of the planetary system and also has implications on the habitability of planets. We would like to extend this type of study to longer period planets which have more amenable temperatures,” concludes Barros. A rtist’s concept of a five exoplanet system. [NASA/JPL-Caltech] !