Two articles, one published in the journal “Monthly Notices of the Royal Astronomical Society” and one in “The Astrophysical Journal Letters”, report independent confirmations of the discovery of the exoplanet Gliese 12 b, which has a size very close to the Earth’s but orbits a red dwarf that has a mass and size that are around a quarter of the Sun’s. Two teams of researchers used observations conducted by NASA’s TESS space telescope and confirmations obtained with other instruments to verify the existence of Gliese 12 b. The available information doesn’t reveal if it has an atmosphere but several factors make it a good candidate for a follow-up search with the James Webb Space Telescope.
The image (NASA/JPL-Caltech/R. Hurt (Caltech-IPAC)) shows the Earth and artistic concepts showing the exoplanet Gliese 12 b in possible versions ranging from no atmosphere to a very thick atmosphere like that of Venus.
The TESS space telescope is currently the main planet hunter. Observations of the star Gliese 12, about 40 light-years away from Earth, revealed a candidate that was of interest to two different teams of researchers. The consequence is that each team used different instruments to verify its existence, obtaining independent confirmation.
The exoplanet Gliese 12 b has a size very close to the size of the Earth and Venus, and this already represents a reason of interest. Its year lasts less than 13 Earth days, meaning it receives much more energy from its star than the Earth receives from the Sun. The estimated energy levels are 85% of what Venus receives from the Sun. As a matter of fact, if it had no atmosphere, the estimated temperature on its surface would be around 42° Celsius, so not too high.
Neither team studying the exoplanet Gliese 12 b was able to verify if it has an atmosphere. The James Webb Space Telescope was also designed to study the possible atmospheres of exoplanets, and this one is in the cosmic neighborhood, yet another reason that makes it a good candidate for this type of follow-up study.
The presence of an atmosphere for the exoplanet Gliese 12 b is crucial for the estimates of its habitability potential. However, verifying it is considered very useful by researchers also to be able to make comparisons with the atmospheres of Earth and Venus reconstructing the different histories together with the reasons that led to similarities and/or differences.
In the history of a planet’s evolution, its star’s activity must also be taken into account. Red dwarfs are small but can be very active with very powerful flares that can sweep away a planet’s atmosphere. However, both published studies indicate that Gliese 12 isn’t very active, and that’s a positive sign.
Follow-up studies of the exoplanet Gliese 12 b will also be able to provide a precise estimate of its mass. Its composition is also important when thinking about the gases that could be emitted during volcanic activity. According to current models, planets can form with an atmosphere composed mostly of hydrogen that is stripped away by stellar winds. That’s considered true for Earth and Venus as well and is another reason why there’s a desire to verify it for planets in other star systems.
