Hubble probes strange weather conditions on hot worlds

Illustration of a Jupiter-sized ultrahot exoplanet

This is an artist’s illustration of the planet KELT-20b orbiting a blue-white star. The giant planet is so close to its star (5 million miles) that the star’s torrent of ultraviolet radiation heats the planet’s atmosphere to more than 3,000 degrees Fahrenheit. This creates a thermal layer where the temperature of the atmosphere increases with altitude. This is the best evidence to date, obtained from the Hubble Space Telescope, of a host star directly affecting a planet’s atmosphere. The hot planet is 456 light-years away. Credit: NASA, ESA, Leah Hustak (STScI)

Hot worlds vaporize most of the dust in their atmospheres

“When you’re hot, you’re hot!” sang country singer Jerry Reed in one of the best pop songs of 1971. Hubble astronomers could change the lyrics to: “when you’re hot, you’re super hot!”

This comes from studying planets that are so precariously close to their parent star that they are roasting in scalding temperatures above 3000 degrees.[{” attribute=””>Fahrenheit. It’s raining vaporized rock on one planet, and another planet’s atmosphere is being “sunburned” by intense ultraviolet radiation from its star. This makes the upper atmosphere hotter rather than cooler.

This Hubble research provides dramatic new insights into the vast range of atmospheric conditions on other worlds, and helps astronomers build better theories for making themselves “DOI: 10.1038/s41586-022-04453-2

“Strong H2O and CO Emission Features in the Spectrum of KELT-20b Driven by Stellar UV Irradiation” by Guangwei Fu, David K. Sing, Joshua D. Lothringer, Drake Deming, Jegug Ih, Eliza M. -R. Kempton, Matej Malik, Thaddeus D. Komacek, Megan Mansfield and Jacob L. Bean, 24 January 2022, Astrophysical Journal Letters.
DOI: 10.3847/2041-8213/ac4968

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

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