Free Astronomy Magazine September-October 2023

23 SEPTEMBER-OCTOBER 2023 ASTRO PUBLISHING elements contribute to the compo- sition of gas giants in our Solar Sys- tem, those planets are too cold for the elements to vaporize into the atmosphere making them virtually undetectable. “Truly rare are the times when an exoplanet hundreds of light-years away can teach us something that would otherwise likely be impossi- ble to know about our own Solar System,” said Pelletier. “That is the case with this study.” The abundance of many of these el- ements closely match the abun- dances found in both our Sun and the exoplanet’s host star. This may be no coincidence and provides ad- ditional evidence that gas-giant planets, like Jupiter and Saturn, form in a manner more akin to star formation — coalescing out of the gas and dust of a protoplanetary disk — rather than the gradual ac- cretion and collision of dust, rocks, and planetesimals, which go on to form rocky planets, like Mercury, Venus, and Earth. Another notable result of the study is the first-ever unambiguous detec- tion of vanadium oxide on an exo- planet. “This molecule is of high interest to astronomers because it can have a great impact on the at- mospheric structure of hot giant planets,” says Pelletier. “This mole- cule plays a similar role to ozone being extremely efficient at heating Earth’s upper atmosphere.” Pelletier and his team are motivated to learn more about WASP-76b and other ultra-hot planets. They also hope other researchers will leverage what they learned from this giant exoplanet and apply it to better our understanding of our own Solar System planets and how they came to be. “Available to astronomers across the globe, the International Gemini Observatory continues to deliver new insights that push our understanding of the physical and chemical structure of other worlds. Through such observational pro- grams we are developing a clearer picture of the wider universe and our own place in it,” said NSF Gem- ini Observatory program director Martin Still. “Generations of researchers have used Jupiter, Saturn, Uranus, and Neptune measured abundances for hydrogen and helium to benchmark formation theories of gaseous plan- ets,” says Université de Montréal professor Björn Benneke, a co-au- thor on the study. “Likewise, the measurements of heavier elements such as calcium or magnesium on WASP-76b will help further under- standing the formation of gaseous planets.” ! W ASP-76b, a so-called “hot Jupiter”, is perilously close to its host star, which is heating the planet’s atmosphere to astounding temperatures and vapor- ized rock-forming elements such as magnesium, calcium and iron, providing in- sight into how our own Solar System formed. [International Gemini Observatory/ NOIRLab/NSF/AURA/J. da Silva/Spaceengine/M. Zamani]