This is Gliese 486 b, the best studied terrestrial planet outside the solar system

Gliese 486 by future exoplanet science

The researcher refers to future studies, such as the formation of planetary magnetic fields in the outer zone of the nucleus with liquid metals, since Gliese 486 b seems to have one like our Earth. These magnetic fields can act as a shield against storms originating from the stellar host and prevent erosion of the atmosphere.

There are several questions to be answered: could such an atmosphere be primitive and made of hydrogen and helium? Or be composed of carbon dioxide and water vapor from volcanic eruptions? could Gliese 486 b have tectonics?

Although this exoplanet seems to be too hot to be habitable, its precise and exact characterization may make it the first exoplanet – and only one at the moment – ​​where these types of questions can be asked. Just a few years ago, trying to find answers was considered science fiction.

The first exoplanet around a star similar to our Sun, 51 Pegasi b, was discovered in 1995. Since then, every year the astronomical community has found exoplanets that are less massive, closer and more similar to Earth.

Various projects and instruments involved

Both Caballero and González-Álvarez collaborate in the CARMENES project, whose consortium is made up of eleven research institutions from Spain and Germany. Its purpose is to monitor some 350 red dwarf stars for signs of low-mass planets using a spectrograph installed on the Calar Alto 3.5m telescope in Almería (Spain).

For this study, the team also obtained spectroscopic observations with the MAROON-X instrument, installed on the Gemini North 8.1 m telescope (USA), and with the STIS instrument, on board Hubble. Photometric observations to derive the planet’s size come from ESA’s CHaracterising ExOPlanets Satellite (CHEOPS) and NASA’s Transiting Exoplanet Survey Satellite (TESS).

The radius of the star was measured with the CHARA array (Center for High Angular Resolution Astronomy) at Mount Wilson, California (USA). A battery of smaller telescopes, including amateur astronomers’ telescopes, were also used to determine the star’s rotation period.

In 2019, the CARMENES consortium discovered the exoplanet that most closely resembles Earth. However, that exoplanet does not transit (i.e. it does not pass in front of its star as seen from the solar system) and therefore its radius is difficult to determine precisely.

Although most of them are not habitable, transiting planets – like Gliese 486 b – are more interesting for the astronomical community because they allow their atmospheres to be investigated and, only for the planetary systems closest to our Sun, their interiors.

The same CARMENES Consortium, in alliance with international teams from the USA, discovered three of the eight closest systems thanks to this type of planets in transit, the last of them announced last week.