Astronomers have discovered that a giant planet, WASP-189b, echoes the composition of its host star, providing the first direct evidence of a foundational concept in astrobiology. This discovery was achieved through the first-ever simultaneous measurement of gaseous magnesium and silicon in a planet’s atmosphere. The team used the Gemini South telescope, one half of the International Gemini Observatory. The findings are published in the journal Nature Communications.
Almost 320 light-years away in the Libra constellation lies WASP-189b, an exoplanet known as an ultra-hot Jupiter (UHJ). UHJs have temperatures high enough to vaporize rock-forming elements like magnesium (Mg), silicon (Si), and iron (Fe), offering a rare opportunity to see these elements using spectroscopy—the technique of breaking up light into its component wavelengths to identify the presence of chemicals.
An international team of astronomers led by Jorge Antonio Sanchez, a graduate student at Arizona State University (ASU), observed WASP-189b using the high-resolution Immersion GRating INfrared Spectrograph (IGRINS) when it was mounted on the Gemini South telescope in Chile. This powerful instrument allowed them to simultaneously measure the magnesium and silicon content of the exoplanet’s atmosphere.
