Astronomers have made detailed observations of an incredibly extreme exoplanet, finding severe surface temperatures in the region of 3,200 degrees Celsius (5,792 degrees Fahrenheit).
These temperatures – measured by the European Space Agency’s typical ExOPlanet (or CHEOPS) satellite – are enough to melt all 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 actually as toasted as some small dwarf stars.
The new discoveries immediately identified 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 constant “day”
“WASP-189b is particularly interesting because it is a gas giant that orbits very close to its host star,” said astrophysicist Monica Lendl of the University of Geneva in Switzerland. “It takes less than three days to orbit its star and it is 20 times closer to it than the Earth to the Sun.”
HD 133112 is the host star in question, 2000 degrees Celsius (3600 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 rotates so fast that it is pulled out at its equator.
The WASP-189b is too far (326 light-years) and too close to HD 133112 to be observed directly, but CHEOPS knows some tricks. First, he observes the exoplanet as it passes behind its star: occultation. He then watches as WASP-189b passes in front of its star: transit.
From these readings, the researchers were able to understand the brightness, temperature, size, shape and orbital characteristics of the exoplanet, as well as additional information about the star it orbits.
Because it is on the scale of Jupiter, but much closer to its host star and much hotter, WASP-189b qualifies as the so-called hot planet Jupiter (you can see where the name comes from). Scientists hope that the information gathered by CHEOPS about WASP-189b will improve our understanding of hot Jupiters in general.
“It’s known that there are only a handful of planets around a handful of planets, and this system is the brightest,” Lendall said. “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 raised by the new CHEOPS study is how WASP-189b is formed at all – its inclined orbit suggests that it formed farther from HD 133112 and was then propelled inward.
In addition to the treasure trove of data provided by this new study, it also shows CHEOPS that work as intended and work well, measuring brightness in deep space with an astonishing level of accuracy.
The satellite has many more missions to move on to the next, with hundreds of exoplanets in the tail for closer observation. The data it collects should teach us more about our own solar system, as well as about the planets outside it.
“The accuracy achieved with CHEOPS is fantastic,” says planetary scientist Heike Rauer of the DLR Institute for Planetary Research in Germany. “Initial measurements already show that the instrument works better than expected. It allows us to learn more about these distant planets.”
The study was published in Astronomy and astrophysics.