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Teegarden is a star so small and so weak that it is very close to Earth – 12.59 light-years – that it was not identified until 2003. Later, its proximity made it an attractive candidate for the search for planets.
Today, a team of astrophysicists announced the discovery of two potentially habitable exoplanets in orbit with Teegarden:
The planets were named Teegarden b and Teegarden c (Teegarden a is the star itself). They were detected with the aid of the CARMENES instrument, a visible and infrared light spectrograph operating from the Observatorio de Calar Alto, Almeria, using the Doppler technique, which allows to to detect the movement produced by the planets in its star that revolves around it. .
This small movement is impossible to detect with the technology that we currently have for most stars, but CARMENES has a precision of one meter per second and can see the speed changes of the M dwarfs or red dwarfs, such as Teegarden a. to provide the conditions allowing liquid water to exist in neighboring orbits, it emits most of its energy in the form of red and infrared waves (CARMENES specialty). Teegarden b and Teegarden c both housed water on their surface.
The German astrophysicist Mathias Zechmeister and his team observe the star Teegarden since the creation of CARMENES three years ago. Their measurements showed the presence of at least two signals that, after months of follow-up, were identified as being two planets.
Teegarden orbits around his star every 4.9 days and Teegarden c does it every 11.4 days. Both have a mass similar to Earth's, but they are much closer to their star than we are to the Sun (2.5 and 4.5% of Earth's distance from the Sun, respectively). However, the Teegarden star has a temperature of 2600ºC, half the sun.
Teegarden B is the planet's most similar exoplanet among the 4058 discoveries so far. It has a similar mass and receives a similar radiation. Its similarity index to the Earth is 0.95. According to the researchers, there is a 60% chance that its surface is hot, with temperatures between 0 and 50 ° C. And if it had an atmosphere similar to that of the Earth, the thermometer would oscillate around 28 ° C. Teegarden c, on the other hand, would have a temperature of -47 ° C, similar to that of Mars.
The problem with this optimistic idea that, being so close to a red dwarf, the two exoplanets will have undergone more severe atmospheric erosion than the Earth because of solar flares, as with Proxima b. They could also undergo a tidal coupling, always showing the same face to their star, like Moon to Earth, and being fried on one side and frozen on the other.
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