Wasp-189 b orbits a star larger and more than 2,000 degrees hotter than the Sun, so it appears to glow blue
September 30, 2020 Share on FacebookShare Share on TwitterTweet Share on WhatsAppShare
The Cheops mission of the European Space Agency (ESA) announced the discovery of Wasp-189 b , a nearby planetary system that contains one of the hottest and most extreme extrasolar planets known so far, as reported on Tuesday by the Instituto de Astrofísica de Canarias (IAC).
The European academic journal Astronomy & Astrophysics , specializing in articles on astrophysics and astronomy, indicated that it is an “ultra-hot Jupiter”, a giant gaseous planet that orbits about twenty times closer to its host star than the Earth is to the Sun. which heats up to extreme temperatures and completes its orbit in 2.7 days.
Wasp-189 b's host star is larger and more than 2,000 degrees hotter than the Sun , so it appears to glow blue.
“There are only a few planets around such hot stars, and this system is by far the brightest,” said Monika Lendl, a researcher at the University of Geneva (Switzerland) and lead author of the study, adding that Wasp-189 b It is also the brightest hot Jupiter that can be observed when it passes in front of or behind its star, which makes the whole system really interesting.
The researchers first used Cheops to observe the concealment of Wasp-189 b as it passed behind its host star.
With the planet being so bright, there is actually a noticeable drop in light that is seen, which comes from the system when it is briefly out of sight, Lendl argues.
This is used to measure the brightness of the planet and estimate its temperature at a ” scorching 3,200 degrees Celsius.”
With these extreme temperatures, even metals such as iron melt and turn into gas, making the planet virtually impossible to inhabit.
The Cheops mission studied the transit of Wasp-189 b in front of its star. Transits can reveal a lot about a planet's size, shape, and orbital characteristics, as was the case with Wasp-189 b, which turned out to be larger than previously thought at nearly 1.6 times the radius of Jupiter.
“We also saw that the star itself is interesting: it is not perfectly round, but larger and colder at its equator than at the poles, which makes the star's poles appear brighter,” said Roi Alonso, a researcher at the IAC and co-author of the article.
It rotates “so fast that it is being pushed out at its equator, and to this asymmetry is added the fact that Wasp-189 b's orbit is tilted, it does not travel around the equator, but passes close to the star's poles.” ' added Alonso.
Seeing such an inclined orbit adds to the mystery of how hot Jupiters form, the ESA statement said.
For a planet to have such a steep orbit, it must have formed farther from its star, and then been pushed inward.
This is believed to happen when several planets within a system dispute a position, or when they receive an external influence – from another star, for example – that disturbs the system, and pushes the gas giant towards its star and into very short orbits and very steep.
According to Alonso, the measurement of such inclination with Cheops suggests that Wasp-189 b experienced such interactions in the past.
This first Cheops result is “tremendously exciting, and represents a definitive initial proof that the mission is delivering on its promise in terms of accuracy and performance,” said Kate Isaak, Cheops project scientist at ESA.
An ESA worker during the launch of the European Cheops mission. (EFE / David Fernández / Archive)
Enric Pallé, IAC researcher and co-author of the article, stated that Cheops has a “unique monitoring role to play in the study of exoplanets “, and will look for transits of planets that have been discovered from the ground and, when possible, will measure more accurately the sizes of planets known to transit their host stars.
In the years to come, Cheops will continue to track hundreds of known planets orbiting bright stars, to build on and expand on what has been done for Wasp-189 b.
The mission is the first in an ESA series of three that focus on the detection and characterization of exoplanets. Furthermore, it has significant potential for discovery, from identifying prime targets for future missions exploring exoplanetary atmospheres to searching for new planets and exomoons.