Astronomers have discovered the youngest hot Jupiters known to date. As reported in an article in The Astronomical Journal, his inatrast is not more than 17 million years. The exoplanet completes one revolution around the parent star in just 7 days, so researchers expect its use to explain how gas giants are so close to their bodies.
Hot Jupiter is a very large celestial body, which consist mostly of gases and have a lot of from 0.1 to 13 Jupiter masses. Unlike the giant planets of the Solar system, hot Jupiters are very close to their bodies, causing their surface is heated to extremely high temperatures. At the same time how hot Jupiters get on such a close orbit, astronomers are still not clear.
To answer this question, Aaron Rizzuto (Aaron C. Rizzuto) from the University of Texas at Austin and colleagues analyzed data from the telescope TESS in the course of the observation OB Association, Scorpius — Centaurus. In particular, the attention of researchers was attracted by the HIP 67522 star, located 480 light-years from Earth. The analysis of the curve of its brightness showed periodic drops in brightness, which can appear with the passage of the planet over the disk of the star. However, young stars, which include HIP 67522, usually covered with dark spots, similar to those we see in the Sun. When a celestial body rotates around its axis, these spots can create a signal similar to the signal arising from the transit of the planet. Therefore, to exclude the possibility of error, the researchers additionally used data from the infrared Observatory “Spitzer”.
It turned out that around the HIP 67522 planet, dubbed HIP 67522 b, with a radius of about 10 earth. As the age of the parent star is known (it is 17 million years), this suggests that the hot Jupiter, apparently, only a few million years younger. This is the young hot Jupiter known to date. The age of the majority of members of this class of exoplanets, as a rule, is more than a billion years.
Astronomers hope that the discovery will help to choose the most preferred scenario of the formation of such gas giants. Today it is assumed that hot Jupiters initially born away from the parent star, with the border of the snow line — the zone where the substance may exist in the form of ice. There planet form the solid core around which the subsequently formed gas shell, and then migrate closer to the sun. However, views on when it happens, vary: while some scientists believe that hot Jupiters are moving to a closer orbit before the dissipation of the protoplanetary disk by gravitational interactions with gas and dust, others say that they migrate later when the disk has already formed other planets, whose gravity pushed them closer to the star.
The existence of such a young gas giant on a close orbit around the sun may be arguments in favor of the first hypothesis. However, to draw final conclusions, it is necessary to find other similar objects.
In February, the astronomers found hot Jupiter, where a year lasts less than earth days. The planet revolves around its star in just 18 hours.