The star of Teegarden is a red dwarf 12.5 light-years away from us, in the constellation of Aries, and astronomically speaking it is one of our neighbors. A cold star, having a surface temperature of “only” 2,700 K, while our Sun has a practically double surface temperature, equal to 5,777 K.
The star owes its name to the astrophysicist Bonnard Teegarden who, searching for dangerous asteroids in the vicinity of the Earth, ended up discovering this curious star in 2003.
A few days ago, after a great research work carried out with the Carmenes spectrograph and the 3.6-meter telescope of the Calar Alto Observatory, in Spain, the discovery of two extrasolar planets located in the habitable area of the star of Teegarden was announced . The discovery was carried out by a team of scientists from the IEEC (Institute of Space Studies of Catalonia). Remember that the habitable zone is the area of a solar system in which liquid water can exist. This is one of the main criteria for determining whether a planet can be habitable or not. However, there are exceptions, such as the ocean of liquid water beneath the surface of Europa, one of Jupiter‘s moons, so it is usually not only based on this to determine the similarity with the Earth.
The discovery was made by measuring the Doppler effect on the lines of the star’s spectrum. Already from the first observations oscillations had been noticed, typical of the presence of planets in orbit. Analyzing these oscillations, the two exoplanets were identified.
The outermost planet, Teegarden c, has a mass similar to that of the Earth, orbiting its star in 11.4 days and is about 6.7 million kilometers away. The innermost planet, Teegarden b, completes an orbit in 4.9 days and is about 3.7 million km from its star. The latter also has a value of Esi (Earth Similarity Index) equal to 0.95, putting it in fact in first place among the most similar exoplanets to the Earth.
The search for exoplanets within our cosmic neighborhood is arousing much interest, and it is estimated that there may be a thousand of them in a 50 light-year radius of our solar system. The difficulty is that nearby stars are scattered homogeneously, forcing astronomers to focus their attention on individual stars. Usually, instead, we prefer to “shoot in the pile”, that is to point a telescope at a region of the sky and study as many stars as possible simultaneously within the region of interest.
Here are the words of Ignasi Ribas, a member of the team of scientists who discovered the two new exoplanets:
Both planets of Teegarden are potentially habitable … In the end we will see if they are actually habitable and perhaps even inhabited.
For more information, please read the article ” The CARMENES search for exoplanets around M dwarfs”.