By detecting heavy winds on HD209458b, a huge exoplanet located 150 light years away that is slightly more than half the mass of Jupiter, the researchers could then measure the movement of the planet as it orbited its host star — also another first for exoplanetary research.
The researchers detected a heavy wind that is blowing carbon monoxide in the planet’s atmosphere up to 10,000 kilometers per hour (hypersonic winds are the fastest winds ever detected on another planet in our solar system were blowing at up to 2,000 kilometers per hour [supersonic] on Neptune, according to previous research). By tracking the movement of the carbon monoxide, the astronomers could then measure the movement of the planet as it orbited its host star.
Instead of using a space-based instrument like NASA’s Spitzer Space Telescope to study the faraway planet, the researchers used a ground-based, high-resolution spectrograph at the European Southern Observatory in Chile that can detect subtle changes in the wavelength of light when a planet transits its star. As HD209458b transited last August, its parent star left what lead author Ignas Snellen from the Leiden Observatory in the Netherlands described as “a fingerprint” of light that filtered through the planet’s atmosphere. The researchers then used the spectrograph to analyze that imprint of light to detect carbon monoxide molecules in the atmosphere. “It seems that H209458b is actually as carbon-rich as Jupiter and Saturn, and this could indicate that it was formed in the same way,” Snellen said.