Extreme exoplanet even more exotic than originally thought

Considered an ultra-hot Jupiter – a place where iron vaporizes, condenses on the night side and then falls from the sky like rain – the fiery, hellish exoplanet WASP-76b may be even more sizzling than scientists can imagine. had imagined.

An international team, led by scientists from Cornell University, the University of Toronto and Queen’s University in Belfast, reports the discovery of ionized calcium on the planet, suggesting an atmospheric temperature higher than expected thought, or strong winds in the upper atmosphere.

The discovery was made in high resolution spectra obtained with Gemini North near the summit of Mauna Kea in Hawaii.

Hot Jupiters are named for their high temperatures, due to the proximity of their stars. WASP-76b, discovered in 2016, is about 640 light years from Earth, but so close to its F-type star, which is slightly hotter than the sun, that the giant planet orbits every 1, 8 earth days.

The research results are the first of a multi-year project led by Cornell, Exoplanets with Gemini Spectroscopy survey, or ExoGemS, which explores the diversity of planetary atmospheres.

“As we remotely sense dozens of exoplanets, spanning a range of masses and temperatures, we will develop a more complete picture of the true diversity of alien worlds – from those warm enough to harbor iron rains to others. with more moderate climates, from those heavier than Jupiter to others not much bigger than Earth, ”said co-author Ray Jayawardhana, Harold Tanner Dean of the College of Arts and Sciences at Cornell University and professor of astronomy.

“It is remarkable that with today’s telescopes and instruments, we can already learn a lot about atmospheres – their constituents, their physical properties, the presence of clouds and even large-scale winds – from planets orbiting stars hundreds of light years away, ”Jayawardhana said.

The group spotted a rare trio of spectral lines in highly sensitive observations of the atmosphere of exoplanet WASP-76b, published in the Letters from astrophysical journals on September 28 and presented on October 5 at the annual meeting of the Division of Planetary Sciences of the American Astronomical Society.

“We see so much calcium; it’s a really strong characteristic,” said first author Emily Deibert, a doctoral student at the University of Toronto, whose advisor is Jayawardhana.

“This spectral signature of the ionized calcium could indicate that the exoplanet has very strong winds in the upper atmosphere,” Deibert said. “Or the atmospheric temperature on the exoplanet is much higher than we thought.”