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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).
These temperatures, measured by the ExOPlanet (or CHEOPS) satellite characteristic of the European Space Agency, 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 basically as warm as 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’ and the other side seeing a permanent ‘night’. It is also gigantic, about 1.6 times the size of Jupiter.
(THAT)
“WASP-189b is especially 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 go around its star, and it is 20 times closer to it than the Earth is from 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 being pushed outward at its equator.
WASP-189b is too far away (326 light years) and too close to HD 133112 to observe directly, but CHEOPS knows a few tricks. First, he observed the exoplanet as it passed behind its star: an occultation. Then, he saw WASP-189b pass in front of its star: a transit.
From these readings, the researchers were able to figure out the exoplanet’s brightness, temperature, size, shape, and orbital characteristics, as well as additional information about the circling star.
Since it is on the scale of Jupiter but much closer to its host star and much hotter, WASP-189b qualifies as a planet called hot Jupiter (you can see where the name comes from). Scientists hope that the information that CHEOPS has collected about WASP-189b will improve our understanding of hot Jupiters in general.
“Only a few planets are known to exist around such hot stars, and this system is by far the brightest,” says Lendl. “WASP-189b is also the brightest hot Jupiter that we can observe when it passes in front of or behind its star, which makes the whole system really intriguing.”
One of the questions that 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 trove of data this new study has provided, it also shows that CHEOPS is working as intended and performing well, measuring brightness in deep space with an astonishing level of precision.
The satellite has many more missions to move on to the next, with hundreds of exoplanets tailed for closer observation. The data it collects should teach us more about our own Solar System, as well as the planets outside of it.
“The precision 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 is performing better than expected. It is allowing us to learn more about these distant planets.”
The research has been published in Astronomy and Astrophysics.
