Calar Alto captures a potentially habitable world
An international investigation has revealed exoplanet moderate and almost terrestrial size, similar to Venus, according to data obtained from space and ground-based telescopes. This exoplanet, named Gliese 12 bis the closest “exo-Venus” discovered to date by the transit method, which observes periodic mini-eclipses caused by the planet’s passage in front of its star.
The discovery attracted notable participation from Spain, especially highlighting measurements made with the CARMENES spectrograph (Calar Alto Searching for high-resolution M-dwarfs using exo-Earths with near-infrared and optical Echelle spectrographs) at the Calar Alto Observatory (CAHA). In addition, observations were carried out using the MuSCAT2 instrument (Multicolor Simultaneous Camera for the Study of the Atmospheres of Transiting Exoplanets) installed on the Carlos Sánchez Telescope (TCS) at the Teide Observatory.
CARMENS, fundamental
Gliese 12 b has a slightly smaller diameter than Earthcomparable to that of Venus (about 12,000 km). CARMENES spectra and other instruments estimate its mass to be 1.5 times that of our planet, as it is a dense and rocky exoplanet. Its equilibrium temperature at the surface will be approximately 42°C, although the final temperature depends on whether it has retained an atmosphere since its formation. A very dense atmosphere can raise temperatures to hundreds of degrees, similar to the greenhouse effect on Venus, which can reach about 450°C.
exoplanet orbits its parent star, Gliese 12, a cool red dwarf star located 39 light years away in the constellation Pisces, in less than 13 days. Gliese 12 is only 27% the size of the Sun and 60% of its surface temperature. The exoplanet’s proximity to its star, only 7% of the distance between Earth and the Sun, means it receives 1.6 times more energy than Earth, which explains its higher equilibrium temperature.
Masayuki Kuzuhara, Associate Professor at the Tokyo Astrobiology Center and co-leader of the research team, comments: “Although we don’t yet know whether Gliese 12 b has an atmosphere, we think of it as an exo-Venus with the size and energy received from its star similar to that of our planetary neighbor in the solar system. The results were published in The Astrophysical Journal Letters.
Unique candidate
Enric Pallet, The IAC researcher and co-discoverer adds: “This is a unique candidate for new atmospheric studies that could help unravel some aspects of the evolution of our own solar system.” Palle notes that although Earth and Venus are similar in size and mass, their histories are very different due to the complete loss of water on Venus. The atmosphere of Gliese 12 b can provide information about the evolution of the atmosphere and the habitability of terrestrial planets.
The decisive factor in preserving the atmosphere is behavior of the parent star. Red dwarfs are typically magnetically active and produce frequent bursts of X-ray and ultraviolet radiation. However, Kuzuhara’s team’s analysis shows that Gliese 12 shows no signs of extreme behavior, making the system an ideal candidate for studying the atmosphere with the James Webb Space Telescope.
Modern technologies make it possible to analyze the chemical composition of the atmosphere. exoplanetary in transit way. This method identifies the molecules present by studying the pattern of chemical signatures generated when starlight passes through a planet’s atmosphere.
“We know only a few planets transient processes nearby that meet the criteria for this type of research; Gliese 12 b is an exceptional candidate for better understanding the diversity of atmospheres around temperate terrestrial planets,” concludes Palle.