Astronomers' discovery of ionized calcium on super-hot Jupiters with "iron rain" suggests that it is more exotic than previously thought

An international team of scientists led by Cornell University, the University of Toronto and Queen's University Belfast reported the discovery of ionized calcium on a "superheated Jupiter" — suggesting that the atmosphere was hotter than previously thought, or that there was strong winds in the upper part of the atmosphere.

The discovery was made in a high-resolution spectrum obtained by the Northern Gemini Telescope in Hawaii.

Hot Jupiters are named for their high temperatures because of their proximity to the stars. WASP-76b was discovered in 2016 and is about 640 light-years from Earth, but is so close to f-type stars that the giant planet orbits its host star every 1.8 Earth days.

The findings are the first of a multi-year project led by Cornell University to investigate exoplanets using Gemini spectroscopy, or ExoGemS, which explores the diversity of planetary atmospheres.

Ray Jayawardhana, co-author Anderson Dean of Harold-Tanner and professor of astronomy at Cornell University's College of Arts and Sciences, said: "As we remotely sense dozens of exoplanets, spanning a range of masses and temperatures, we will have a more complete picture of the true diversity of the alien world – from those that are hot enough to breed 'iron rain' to other planets with milder climates, from those heavier than Jupiter to other planets that are not much larger than Earth.

Jayawardhana said: "With today's telescopes and instruments, we can already learn so much about the atmospheres of planets orbiting stars hundreds of light-years away — their composition, their physical properties, the presence of clouds, and even the patterns of large-scale winds, which is remarkable." ”

The team found three rare spectral lines in highly sensitive observations of the atmosphere of exoplanet WASP-76b, which were published Sept. 28 in the Astrophysical Journal and published Oct. 5 at the annual meeting of the American Astronomical Society's Planetary Science Division.

Lead author Emily Deibert said, "We see so much calcium; it's a very strong trait," said Emily Deibert, a PhD student at the University of Toronto whose supervisor was Jayawardhana.

Deibert said: "This spectral signature of ionized calcium may indicate that the exoplanet has very strong upper atmospheric winds." Or the atmosphere on the exoplanet may be much hotter than we think. ”

Because WASP-76b is tidally locked—that is, one side of it is always facing the star—it has an eternal night face with an average temperature of 2400 degrees Fahrenheit, which is relatively cool. Its average temperature on the eternal day surface is 4400 degrees Fahrenheit.

Deibert and her colleagues examined moderate temperature zones, located on the edge between day and night on the planet. "This exoplanet is moving fast in its orbit, which is why we were able to separate its signals from the starlight." "You can see that the calcareous imprints on the spectrum are moving rapidly with the planets.

Astronomers continue to delve deeper into understanding exoplanets. "Our work, and the work of other researchers, is paving the way for exploring the atmosphere of the terrestrial world beyond the solar system," the astronomer said. ”