Astronomers are convinced that they have found two new Earth-like planets in our galaxy, and both resemble our planet so much that they are now among the 19 best-known exoplanets with potentially habitable environments.
One of these two planets orbits a neighboring star in the constellation Aries, which is only 12.5 light-years away, and possibly has the closest resemblance to the Earth we have discovered so far.
"The two planets resemble the inner planets of our solar system," explains senior author Mathias Zechmeister, astrophysicist at the University of Göttingen.
"They are only slightly heavier than the earth and are located in the so-called residential zone, where water can be in liquid form."
Despite its proximity, this nearby tea star was only discovered in 2003. It is about ten times lighter than our own sun and one of the smallest stars we know, the old red dwarf, which is about 8 billion years old, has proved to be a challenge for research.
According to the team, other planetary systems around similar stars have been detected using the transit method whenever a rotating planet passes in front of a star, blocks the view of the earth and the bright sky object that is to be darkened for a brief moment.
However, the alignment and darkness of Teegarden would not be appropriate for this method. Therefore, astronomers instead used the next generation CARMENES telescope designed specifically for such situations. The instrument was located at the Spanish Calar Alto Observatory and allowed researchers to search for changes in the radial velocity of the mini-star.
After three years of close observation, more than 200 measurements have been performed indicating the existence of two new planets, now called Teegarden b and Teegarden c.
To ensure that the radial velocity data that indicates these planets were not distorted by variations in the brightness of the star, the researchers supplemented their observations with photometric data (light measurements) that cross Teegarden's star were raised.
"These studies show that the signals of the two planets are not due to the activity of the star, although we could not prove the transits of the two new planets," says the astronomer Victor Sánchez Béjar of the Instituto de Astrofísica de Canarias ( AIS).
Teegarden b is the innermost planet; According to the international team, there is a 60 percent probability of a moderate surface environment, which is between 0 ° and 50 ° C, and probably closer to 28 ° C. Teegarden c, on the other hand, is farther out and has a surface temperature that is more similar to that of Mars and is around -47 ° C.
Due to their minimum mass and solar radiation, both planets have created the catalog of habitable exoplanets. In fact, Teegarden b has achieved the highest Earth Similarity Index (ESI) ever achieved.
While this does not necessarily mean that every planet is actually habitable, it is certainly a promising sign. Zechmeister said The Guardian that these planets, if equipped with atmospheres, could be quite life-friendly.
"The planets Teegarden's star b and c are the first planets discovered using the radial velocity method around such an ultra-cool dwarf," writes the team in an article describing the discovery.
"Both planets have a minimum mass It is expected that they have earth-like radii near a mass of the earth and a rocky, partially iron or water-containing composition."
Lauren Weiss, an astrophysicist at the University of Hawaii who was not involved in this research, said National Geographic that there are still some technical details which need to be worked out, but she was impressed with the overall quality of the data.
While the team predicts that Teegarden b will complete its orbit in 4.9 earth days and c does so in 11.4 days, Weiss argues that their journey may be even faster than it would be. Inevitably, they reduce their habitability ,
What's more, she adds, we do not have to know exactly how long Teegarden needed to spin around its axis. Given that astronomers used radial velocity measurements to make their discovery, one of these planetary detections could still be a star rotation artifact – but probably not both. On habitable planets, Teegardeen is an excellent candidate for future research, and its potential, life We were pretty excited.
The research was published in Astronomy & Astrophysics .