Scientists have discovered a hot Jupiter class exoplanet orbiting its parent star in just 18 hours. This is the shortest orbital period ever observed for a planet of this type. The research is published in the Monthly Notices of the Royal Astronomical Society.
The planet NGTS-10b was discovered at a distance of about a thousand light-years from Earth as part of the Next-Generation Transit Survey (NGTS), which aims to search for exoplanets up to Neptune using the transit method. The essence of the method lies in the fact that astronomers observe the stars for the detection of a clear drop in brightness, which indicates that a planet has passed in front of them.
The robotic exoplanet search system NGTS, consisting of twelve telescopes, was deployed at the Paranal Observatory in the Atacama Desert in Chile. At any given moment, the system observes 100 square degrees of the sky - an area containing about 100 thousand stars. One of these stars has attracted the attention of astronomers due to the very frequent dips in its luminosity associated with the rapid passage of the planet.
"We are delighted to announce the discovery of NGTS-10b, an extremely short, periodic, Jupiter-sized planet orbiting a star not too dissimilar to our Sun," said research director, British astronomer James McCormac of the University of Warwick, in a press release. - Although theoretically hot Jupiters with short orbital periods of less than 24 hours are easiest to detect due to their large size and frequent transits, they have proven to be extremely rare. Of the hundreds of known hot Jupiters, only seven currently exist with orbital periods of less than one Earth day. " …
One year on the surface of this gas giant, similar in size and composition to Jupiter, takes only 18 hours. It rotates so fast because it is very close to the star - the distance to it is only twice the diameter of the star itself. Most likely, the planet is constantly facing the star with only one side of it, which heats up, according to scientists, up to one thousand degrees Celsius. The star itself is about 30 percent smaller than our Sun and a thousand degrees colder.
Compared to the solar system, NGTS-10b is located 27 times closer to its sun than Mercury is to ours. Scientists note that this is very close to the so-called Roche limit - the point at which the star's tidal forces will eventually tear the planet apart.
The authors calculated that the exoplanet is spiraling, gradually approaching the star, and will cross the Roche limit in 38 million years. That is, it is doomed. The researchers consider it a great fortune that they were able to observe the position of the planet at a turning point in its life cycle, which will help them answer questions about the evolution of planets of this type.
Another author of the article, David Brown of the same University of Warwick, adds: “These ultra-short-orbiting planets are believed to migrate from the outer regions of their solar systems and are eventually absorbed or destroyed by a star. this short periodic orbit. But it is also possible that the processes by which the planet migrates towards the star are less efficient than we think, in which case the planet could live in this configuration for a longer period of time."
Astronomers plan to apply for instrument time to continue observing NGTS-10b over the next decade and using high-precision measurements to determine whether this planet will remain in its orbit or continue spiraling closer to the star. This will largely determine the future view of scientists on the evolution of hot Jupiters.
"Everything we know about planet formation tells us that planets and stars form at the same time," said Daniel Bayliss, who also participated in the study.- The model we have suggests that the star is about ten billion years old and the planet too. We see her in the last stages of life. Over the next ten years, the planet may begin to grow. If we see that the orbital period starts to decrease and the planet starts to rotate, we can tell a lot about the composition of the planet."