Free Astronomy Magazine September-October 2023

22 SEPTEMBER-OCTOBER 2023 ASTRO PUBLISHING in the atmosphere of WASP-76b. The presence and relative amounts of these elements can provide key insights into exactly how giant gas planets form — something that re- mains uncertain even in our own Solar System. The results are pub- lished in the journal Nature . Since its discovery in 2013 during the Wide Angle Search for Planets (WASP) program, many astronomers have studied the enigmatic WASP- 76b. These studies have led to the identification of various elements present in the hot exoplanet’s at- mosphere. Notably, in a study pub- lished in March 2020, a team concluded that there could be iron rain on the planet. Aware of these existing studies, Ste- fan Pelletier, a PhD student with the Trottier Institute for Research on Ex- oplanets at the Université de Mon- tréal and lead author on the paper, was inspired to explore the myster- ies of this strange exoplanet and the chemistry of its searing atmosphere. In 2020 and 2021, using Gemini North’s MAROON-X (a new instru- ment specially designed to detect and study exoplanets), Pelletier and his team observed the planet as it passed in front of its host star on three separate occasions. These new observations uncovered a number of rock-forming elements in the at- mosphere of WASP-76b, including sodium, potassium, lithium, nickel, manganese, chromium, magnesium, vanadium, barium, calcium, and, as previously detected, iron. Due to the extreme temperatures of WASP-76b’s atmosphere, the ele- ments detected by the researchers, which would normally form rocks here on Earth, are instead vaporized and thus present in the atmosphere in their gaseous forms. While these Different rock constituents detected in a hot exoatmosphere by NOIRLab − Charles Blue W ASP-76b is a strange world. Located 634 light- years from Earth in the di- rection of the constellation of Pisces, the Jupiter-like exoplanet or- bits its host star at an exceptionally close distance — approximately 12 times closer than Mercury is to the Sun — which heats its atmosphere to a searing 2000°C. Such extreme temperatures have “puffed up” the planet, increasing its volume to nearly six times that of Jupiter. At such extreme temperatures, min- eral- and rock-forming elements, which would otherwise remain hid- den in the atmosphere of a colder gas-giant planet, can reveal them- selves. Using the Gemini North tele- scope, one half of the International Gemini Observatory operated by NSF’s NOIRLab, an international team of astronomers has detected 11 of these rock-forming elements