- 2847 - EXOPLANETS - CHEOPS - exploring other planets. September, 2020, eight months after the space telescope CHEOPS started its journey into space. CHEOPS is the first European Space Agency mission dedicated to characterizing known exoplanets. Exoplanets are planets outside the Solar System. They were first discovered in 1995.
--------------------------- 2847 - EXOPLANETS - CHEOPS - exploring other planets
- The Science Operations Center of CHEOPS is located at the observatory of the University of Geneva. Using data from the CHEOPS satellite, scientists have recently carried out a detailed study of the exoplanet WASP-189b.
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- WASP-189b is one of the most extreme planets in the universe. It is an exoplanet orbiting the star HD 133112, one of the hottest stars known to have a planetary system. The WASP-189 system is 322 light years away and located in the constellation Libra.
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- WASP-189b is a gas giant that orbits very close to its host star. It takes less than 3 days for it to circle its star, and it is 20 times closer to it than Earth is to the Sun. The planet is more than one and a half times as large as Jupiter.
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- WASP-189b has a permanent day side, which is always exposed to the light of the star, and, accordingly, a permanent night side. This means that its climate is completely different from that of the gas giants Jupiter and Saturn in our solar system.
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- The estimated temperature of WASP-189b is 3,200 degrees Celsius. Planets like WASP-189b are called "ultra-hot Jupiters". Iron melts at such a high temperature, and even becomes gaseous. This object is one of the most extreme planets we know of.
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- Highly precise brightness measurements are required for this exploration. We cannot see the planet itself as it is too far away and too close to its host star. When a planet passes in front of its star as seen from Earth, the star seems fainter for a short time. This phenomenon is called a “transit“.
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- Because the exoplanet WASP-189b is so close to its star, its dayside is so bright that we can even measure the 'missing' light when the planet passes behind its star; which is called an “occultation“.
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- The planet does not reflect a lot of starlight. Instead, most of the starlight gets absorbed by the planet, heating it up and making it shine. The planet is not very reflective because there are no clouds present on its dayside. Clouds cannot form at such high temperatures.
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- The transit of this gas giant in front of its star is asymmetrical. This happens when the star possesses brighter and darker zones on its surface. The star itself rotates so quickly that its shape is no longer spherical; but ellipsoidal. The star is being pulled outwards at its equator.
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- The star is considerably larger and more than two thousand degrees Celsius hotter than our sun. Because it is so hot, the star appears blue and not yellow-white like the sun.
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- January, 2020 Cheops took its first, intentionally blurred images of stars. The deliberate defocusing is at the core of the mission’s observing strategy, which improves the measurement precision by spreading the light coming from distant stars over many pixels of its detector.
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- More than 4,000 planets, and still counting, are known to be orbiting stars other than the Sun. The goal is to characterize these planets, providing constraints on their structure, formation and evolution.
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- Cheops is a small, 1.5 meter sized satellite. To measure how well Cheops performs scientists had to first needed to observe stars whose properties are well known, stars that are well-behaved. hand-picked to be very stable, with no signs of activity.
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- The commissioning period demonstrated that Cheops achieves the required photometric precision and, importantly, it also showed that the satellite can be commanded by the ground segment team as needed to perform its science observations.
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- Cheops is to measure planet sizes with unprecedented precision and accuracy and to determine their densities by combining these with independent measurements of their masses.
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- Another of the targets was HD 93396, a subgiant yellow star located 320 light-years away, slightly cooler and three times larger than our Sun. The focus of the observations was KELT-11b, a puffy gaseous planet about 30% larger in size than Jupiter, in an orbit that is much closer to the star than Mercury is to the Sun.
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- The light curve of this star shows a clear dip caused by the eight hour-long transit of KELT-11b. From these data, the scientists have determined very precisely the diameter of the planet: 181,600 kilometers , plus or minus 4,300 km.
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- A ‘hot super-Earth’ planet , known as 55 Cancri e. A ‘warm Neptune’, GJ 436b, is losing its atmosphere due to the glare from its host star.
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- There is so much more to learn from exoplanet observations. We are just getting started. Stay tuned, maybe one of them will get in touch with us?
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------------------------------- Other Reviews about exoplanets;
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- 2770 - EXOPLANETS - are we alone? Some significant developments need to happen before we can answer the question with any confidence: We will get better at detecting Earth-like planets in the habitable zone and even be able to detect what's in their atmospheres (if they have one).
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- 2702 - EXOPLANETS - new discoveries? If astronomers do detect an exoplanet with a significant oxygen atmosphere, that can only mean an alien biosphere has created it. It is only a matter of time before enough planetary atmospheres will have been surveyed to find one with such life signs. When that day dawns, we will have written a new chapter in the search for life and be able to actually estimate how much life exists in the universe!
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- 2280 - We know there is life in the Universe. We are living proof of that. But is there life on exoplanets which are planets around other suns outside our own solar system? Exoplanets are common, we have found over 4,000 but as for life we are the only evidence so far.
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- 2233 - EXOPLANETS- The TESS Space Mission. The next generation exoplanet hunter is TESS, Transiting Exoplanet Survey Satellite, has already found eight confirmed planets in its first four months of observing and some are unlike anything astronomers have seen before.
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- September 29, 2020 2847
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