Some planets are experiencing summers that never end. For example, the hot Jupiter WASP-69b, which is roasted close to its parent star, was discovered by telescopes to be dragging a vapor tail 56 kilometers long, seven times longer than the planet itself.
Since humans discovered the first exoplanet orbiting a star other than the sun more than 30 years ago, we have confirmed more than 5,000 exoplanets so far. We can evaluate them through attributes such as planet mass, radius, and orbital period around their parent star. Classification.
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But we have seen surprising results: exoplanets include hot Earth and hot Jupiters, but no hot Neptunes; there are a large number of super-Earths and mini-Neptunes (about half the size of Neptune and 200% of the radius of the Earth), but none with a radius between The planet in between.
Astronomers are struggling to solve this mystery without convincing direct supporting evidence, but a new paper studying the evaporating exoplanet WASP-69b may provide key clues to the above issues.
In the past 10 years, we have learned that most stars have at least one planet, and the planet orbits the parent star closer than Mercury orbits the sun. Therefore, the planet’s atmosphere is subject to radiation erosion from the parent star, which is why most of the planets we have discovered Planet type.
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WASP-69b is classified as a hot Jupiter. It is about the same size as Jupiter and is about 160 light-years away from the Earth. It was discovered 10 years ago. Its orbital period around its parent star is less than 4 days. In comparison, the planet closest to the sun is Mercury’s orbital period is 88 days.
Originally observed with the 3.5-meter telescope of Karaato Observatory and the 5-meter telescope of Palomar Mountain Observatory, no trace of WASP-69b was found; the new study used the larger 10-meter telescope and NIRSPEC spectrometer of Keck Observatory to detect WASP-69b. A more detailed structure observation of the escape atmosphere of 69b was conducted, and the results showed that the gases (hydrogen and helium) escaping from WASP-69b were guided by high-energy radiation and stellar winds to form an ultra-long vapor tail that was pushed toward the earth.
Because WASP-69b is so close to its scorching parent star, its atmospheric material boils and evaporates at a rate of 200,000 tons per second.
Fortunately, WASP-69b’s atmosphere will not be completely evaporated. Since WASP-69b has a mass of about 90 times that of the Earth and a very sufficient material reserve, even losing part of its mass will not have a big impact on the planet’s life cycle. At least before the star reaches the end of its life, WASP-69b will not lose its entire atmosphere. crisis.
The planet still shows high resilience in the face of such extreme environments. Optimistically, the planet’s ability to withstand extreme changes may be far beyond our imagination.
new paperPublished in The Astrophysical Journal.
(Source of first picture:UCLA）
