Astronomers have made detailed observations of an incredibly extreme exoplanet, detecting brutal surface temperatures in the region of 3,200 degrees Celsius (5,792 degrees Fahrenheit).
Those temperatures – measured by the ExOPlanet satellite that characterizes the European Space Agency (or CHEOPS) – are enough to melt all the rocks and metals and even turn them into a gaseous form.
While the exoplanet, called WASP-189b, is not as hot as the surface of our Sun (6,000 degrees Celsius or 10,832 degrees Fahrenheit), it is basically toasty like some small dwarf stars.
The new findings immediately identify WASP-189b as one of the most extreme planets ever discovered. It has an orbit of only 2.7 days around its star, with one side seeing a permanent “day”
“WASP-189b is particularly interesting because it is a gas giant that orbits very close to its host star,” says astrophysicist Monika Lendl of the University of Geneva in Switzerland. “It takes less than three days to circle its star, and it is 20 times closer to it than Earth is to the Sun.”
HD 133112 is the host star in question, 2,000 degrees Celsius (3,600 degrees Fahrenheit) hotter than our Sun, and one of the hottest stars known to have a planetary system around it. CHEOPS also made an interesting discovery about this celestial body: it spins so fast that it is pulled outward at its equator.
WASP-189b is too far (326 light years) and too close to HD 133112 to be able to observe it directly, but CHEOPS knows a few tricks. First, he observed the exoplanet as it passed behind its star – an occultation. Then, he watched WASP-189b pass in front of his star – a transit.
From these readings, the researchers were able to understand the exoplanet’s brightness, temperature, size, shape and orbital characteristics, as well as some extra information about the star that is circling.
Because it is on the Jupiter scale but much closer to its host star and much hotter, WASP-189b qualifies as a so-called hot planet Jupiter (you can see where the name comes from). Scientists hope that the information CHEOPS gleaned about WASP-189b will improve our understanding of hot Jupiter in general.
“Only a handful of planets are known to exist around such hot stars, and this system is by far the brightest,” Lendl says. “WASP-189b is also the brightest hot Jupiter we can observe as it passes in front of or behind its star, making the whole system truly intriguing.”
One of the questions the new CHEOPS research has raised is how WASP-189b formed in the first place – its inclined orbit suggests that it formed further away from HD 133112 and was then driven inward.
In addition to the treasure trove of data provided by this new study, it also shows CHEOPS works as expected and performs well, measuring brightness in deep space with a staggering level of accuracy.
The satellite has many other missions to move on to the next, with hundreds of exoplanets queuing up for closer observation. The data it collects should teach us more about our Solar System, as well as the planets outside of it.
“The accuracy achieved with CHEOPS is fantastic,” says planetary scientist Heike Rauer of the DLR Institute of Planetary Research in Germany. “Initial measurements already show that the instrument is performing better than expected. It is allowing us to learn more about these distant planets.”
The research was published in Astronomy and astrophysics.