CHEOPS investigates very extreme exoplanet

The first data collected by ESA’s space probe, eight months after its launch, was recently published in Astronomy & Astrophysics.

For some time now, space agencies have been looking for new planets orbiting a star other than our sun. For this purpose, NASA developed exoplanet hunters Kepler (now retired) and its successor TESS. Thanks to the efforts of these two space telescopes, among others, know of the existence of more than four thousand exoplanets.

But it also ends there: we know that they exist and nothing more. Space probe CHEOPS, which came about thanks to ESA, will change this. The spacecraft’s job is to fathom distant exoplanets. And now the first scientific results of this recently started mission have been announced.

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WASP-189b

CHEOPS examined WASP-189b. This exoplanet orbits one of the hottest stars, called HD 133112, known to have a planetary system. This WASP-189 system is 322 light-years from Earth and is located in the constellation Libra (Libra).

WASP-189b falls into the category of ultra-hot Jupiter, a fairly new class of exoplanets. Hot Jupiters have a mass similar to or heavier than Jupiter and orbit their parent star at a very close distance. 189b, for example, circled its star in just three days.

This makes the temperature on the exoplanet absurdly high. On the day side of WASP-189b, the mercury quickly rises to 3200 degrees Celsius. That’s hot enough to vaporize iron. Astronomer Monika Lendl, of the University of Geneva, calls the exoplanet studied one of the most extreme to date.

The fact that it gets so hot on only one side of the exoplanet is because the same side of WASP-189b always faces its parent star – just like the moon. That phenomenon is called synchronous rotation.

Occultatie

The researchers were unable to directly see the exoplanet itself. It is too far away from Earth and too close to its parent star for that. But thanks to the transition method – a planet sliding in front of its star (a transition), causing a dip in brightness every so often – they were still able to observe WASP-189b.

And that’s not the only way the astronomers can “see” the exoplanet. Lendl: “Because WASP-189b is so close to its star, its day side is so bright that we can even measure the ‘missing’ light as the planet moves behind its star.” This phenomenon becomes occultatie called (covering).

Finally, the first CHEOPS data also revealed that star HD 133112 is not spherical but ellipsoid. The celestial body apparently spins so fast that it is flattened at the poles and wider at the equator. Furthermore, the star is considerably larger and more than two thousand degrees warmer than our sun. Because HD 133112 is so hot, it appears blue and not yellowish white like the sun.

In short, the first scientific results from CHEOPS are not the least. Astronomer Willy Benz: “We expect even more spectacular findings about exoplanets. The following papers are already in preparation. ”

Sources: Astronomy & Astrophysics, University of Bern via EurekAlert!

Image: ESA / ATG medialab

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