Astronomers have proposed a new method of finding planets with the help of two telescopes — presumably the method will allow to see not only close to the star body, but less hot extrasolar planets with large transit time. Scientists tested the approach and found so warm a Saturn, which completes one revolution around the parent star in 35 days, reported in The Astrophysical Journal.
To date, most known exoplanets were discovered by the transit method. It is based on the observation of the change in brightness of a star when it passes in front of another heavenly body. Despite the fact that this method is extremely useful in the search for exoplanets and allows to estimate their size, it does have its drawbacks. The main one is that telescopes can observe the star only a limited amount of time, and therefore, they usually register short-period planets that manage to make at least two transit. As a result, many of the open astronomers of the celestial bodies be located very close to their bodies, and therefore very hot. From the point of view of the potential habitability of much more interesting can be objects that are more removed from the parent star.
Astronomer Samuel Gill (Samuel Gill) from the University of Warwick, together with colleagues invited to look cooler in the world using two telescopes. Their method, the researchers tested on the planet NGTS-11b, which rotates around similar to our Sun a yellow dwarf star, raspolozhennogo 620 light years from Earth.
For the first time the woman was registered with the TESS telescope in 2018. But since the area of the observation space Observatory is divided into 26 sectors, many of these sectors, including the one where NGTS-11b, the telescope sees only 27 days. As a result, TESS managed to register only a single transit, which is not enough to say with certainty about the discovery of a new planet. The group, Gill continued observations with the second telescope, the Next-Generation Transit Survey (NGTS). Tool was watching the parent star during 79 nights and caught two new transit about a year later after the first one.
On the basis of the light curve of the star, and Doppler spectroscopy, the researchers identified key features of the planet. It turned out that NGTS-11b is a warm Saturn, which completes one revolution around the sun in 35 days. Its mass is 0.3 of the mass of Jupiter, and a radius of 0.8 of the radius of Jupiter. However, the most noteworthy is the fact that NGTS-11b is much colder in the past many open planets, astronomers have estimated it at a stable temperature of 160 degrees Celsius, which is less than the temperature of mercury or Venus. Despite the fact that the climate on NGTS-11b still too hot to sustain life, it is still much closer to the habitable zone of stars like our Sun.
According to Gill, hundreds of single transits, was TESS, can become targets for NGTS. “Some of them will be small rocky planets in potentially habitable zone, which would be rather cool to them there was liquid oceans and possible extraterrestrial life,” he concludes.
In January it became known that TESS registered the first earth-like planet in the habitable zone. The star around which it turns the celestial body, located 100 light years from Earth.