The discovery of an exoplanet, especially with unique atmospheric properties, always catches the eye. Astronomers at the Harvard-Smithsonian Center for Astrophysics, a Cambridge-based astrophysics research institute, have now detected an exoplanet, almost Jupiter-like, but without clouds or haze in its observable atmosphere.
This gas giant, named WASP-62b, was first detected in 2012 through the Wide Angle Search for Planets (WASP) South survey. But its atmosphere had never been closely studied until now. Gas giants are planets that are composed mostly of gases -- the likes of Uranus, Neptune, Saturn and Jupiter, which are in our solar system.
An official news release from the Centre for Astrophysics explains how WASP-62b, which is 575 light years away and about half the mass of Jupiter, is known as a “hot Jupiter”. Unlike its namesake planet, which takes nearly 12 years to orbit the sun, WASP-62b completes a rotation around its star in just four-and-a-half days. This proximity to the star makes it extremely hot, hence the name "hot Jupiter," the release adds.
Munazza Alam, a graduate student at the Center for Astrophysics who led the study, used the Hubble Space Telescope to record data and observations of the planet using spectroscopy, the study of electromagnetic radiation to help detect chemical elements. Alam monitored WASP-62b as it swept in front of its host star three times, making visible light observations, which can help detect the presence of sodium and potassium in a planet's atmosphere, the release explains. And, while there was no evidence of potassium, sodium's presence was clear. The team behind the study was able to view the full sodium absorption lines in their data, or its complete fingerprint, the release adds. Clouds or haze in the atmosphere of the planet would have obscured the sodium signature, Alam says in the release. Usually, astronomers can only make out small hints of its presence. The findings around this discovery were published in the Astrophysical Journal Letters this month.
Cloud-free planets are quite rare -- astronomers estimate that less than 7 percent of exoplanets have clear atmospheres, based on recent research. The first and only other known exoplanet with a clear atmosphere was discovered three years ago. Named WASP-96b, it is classified as a hot Saturn. This makes the discovery of WASP-62b all the more special.
One of the benefits of studying exoplanets with cloudless or clear atmospheres is that it makes it easy for scientists to analyze the composition of planets, which can help identify what they are made of. Now, researchers at the Center for Astrophysics are hoping to learn more about WASP-62b with the James Webb Space Telescope, which is due to be launched later this year and will offer far more improved technologies than its predecessors.