An article published in the journal “Monthly Notices of the Royal Astronomical Society” reports a study on the exoplanet NGTS-10b, an ultra-hot Jupiter whose year lasts only about 18 hours. A team of researchers led by Dr James McCormac of the British University of Warwick used data collected during the NGTS survey to identify NGTS-10b thanks to its transits in front of its star. It’s the hot or ultra-hot Jupiter closest to its star observed so far, so close to it that in the distant future it could approach the point of being destroyed. This makes it an interesting object of study, also because observations conducted for several years will measure its orbit’s changes to understand if it’s really doomed.
The main purpose of the Next-Generation Transit Survey (NGTS) project, conducted with an array of telescopes in Chile, is to discover or verify candidates for relatively small exoplanets, meaning super-Earths up to Neptune-sized ones, through the transit method by measuring with great precision the slight drop in brightness that occurs when an exoplanet passes between its star and the Earth. However, giant planets can also be found, especially if they’re hot Jupiters, so called because they’re close to their star and therefore receive from it an amount of heat that significantly heats their surface. This time they found one extreme even for that category.
About 1000 light years from Earth, the star NGTS-10 has a mass and size that is about 60% of the Sun’s, with an age estimated at almost 10.5 billion years. It’s a star system more than twice as old as the solar system and this already makes interesting the study of what’s at least for now its only planet. NGTS-10b has a mass that is slightly more than twice the planet Jupiter’s for a diameter which is approximately 20% greater than Jupiter’s. Its distance from NGTS-10 is only twice the star’s diameter and the consequence is a temperature on the surface that probably is higher than 1,000° Celsius, so it can be considered an ultra-hot Jupiter. It’s almost certainly tidally locked to its star, which means that it always shows the same face and there’s a significant difference in temperature between its day side and night side.
This type of exoplanet is interesting because according to theoretical models giant planets form far from their stars, in areas of the protoplanetary disk where there’s enough gas to form such massive planets. We know many hot Jupiters, which indicates that planets can move significantly throughout their lives. Perhaps they start migrating towards their star already during the formation period interacting with the protoplanetary disk or perhaps interacting with other more evolved planets.
Dr. James McCormac and his colleagues intend to monitor the orbit of the exoplanet NGTS-10b over the next decade because it’s interesting in the study of the migration of planets and in particular to understand if it will keep on approaching its star until it’s destroyed. Maybe astronomers were lucky to find out in the last phase of its life or maybe it will take longer than expected to be destroyed. The data that will be collected over the next years will be useful to improve our models.
