According to Warwick astrophysicist and lead researcher Tom Louden, winds on exoplanets are nothing new or surprising, but this marks the first time researchers have been able to “directly measure and map a weather system” on these planets. The exoplanet in question is called HD 189733b, a hot planet not unlike Jupiter that is located in the constellation Vulpecula, some 63 light years away in Earth.
A few factors made it possible for the Warwick researchers to measure wind speed in the exoplanet, including spectroscopy knowledge and their understanding of the Doppler Effect. The researchers used the High Accuracy Radial Velocity Planet Searcher telescope in La Silla, Chile to gain insights on the exoplanet’s atmosphere, tracking how sodium atoms absorb radiation on the host star. That covered the spectroscopy aspect, and as the scientists analyzed these insights, they were able to get signatures of the Doppler Effect and come up with a figure for the wind velocity on both sides of HD 189733b.
“As parts of HD 189733b’s atmosphere move towards or away from the Earth the Doppler effect changes the wavelength of this feature, which allows the velocity to be measured,” Louden’s statement continued. “The surface of the star is brighter at the center than it is at the edge, so as the planet moves in front of the star the relative amount of light blocked by different parts of the atmosphere changes.” Louden also noted that this marks the first time such information was used to measure velocities on opposite ends of a planet independent from each other, thus allowing his team to come up with a velocity map.
Results of the study were published this week in the Astrophysical Journal.