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Astronomers Detect Water Vapor On Small Exoplanet In “Landmark Discovery”

Astronomers have utilized the Hubble Space Telescope to make a “landmark discovery” of water molecules on a small exoplanet located 97 light-years away from Earth, according to reports from CNN

The planet is scientifically named GJ 9827d, and is about twice Earth’s diameter, and according to a new report published last week in The Astrophysical Journal Letters, is the smallest exoplanet that has been found to have water vapor in its atmosphere. 

While the presence of water on any planet could be a sign of life, the astronomers involved in this research said it was unlikely that this planet has life on it due to its hot temperature that likely turns the water in the atmosphere to steam. 

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“Water on a planet this small is a landmark discovery. It pushes closer than ever to characterizing truly Earth-like worlds,”  said study coauthor Laura Kreidberg, managing director of the atmospheric physics of exoplanets department at the Max Planck Institute for Astronomy in Heidelberg, Germany, in a statement.

The planet itself is reported to reach temperatures of 800 degrees Fahrenheit (427 degrees Celsius), hence the conclusion that it’s inhospitable. 

“This would be the first time that we can directly show through an atmospheric detection, that these planets with water-rich atmospheres can actually exist around other stars. This is an important step toward determining the prevalence and diversity of atmospheres on rocky planets,” said study coauthor Björn Benneke, professor at the University of Montreal’s Trottier Institute for Research on Exoplanets, in a statement

“Our observing program, led by principal investigator Ian Crossfield of (the University of Kansas) in Lawrence, Kansas, was designed specifically with the goal to not only detect the molecules in the planet’s atmosphere, but to actually look specifically for water vapor. Either result would be exciting, whether water vapor is dominant or just a tiny species in a hydrogen-dominant atmosphere,” said lead study author Pierre-Alexis Roy, a doctoral student at the University of Montreal’s Trottier Institute, in a statement

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According to the study, astronomers have observed GJ 9827d during 11 transits within the past three years. 

“Until now, we had not been able to directly detect the atmosphere of such a small planet. And we’re slowly getting into this regime now. At some point, as we study smaller planets, there must be a transition where there’s no more hydrogen on these small worlds, and they have atmospheres more like Venus (which is dominated by carbon dioxide),” Benneke said. 

“Observing water is a gateway to finding other things. This Hubble discovery opens the door to future study of these types of planets by the James Webb Space Telescope. JWST can see much more with additional infrared observations, including carbon-bearing molecules like carbon monoxide, carbon dioxide, and methane. Once we get a total inventory of a planet’s elements, we can compare those to the star it orbits and understand how it was formed,” said study coauthor Thomas Greene, astrophysicist at NASA’s Ames Research Center in California’s Silicon Valley. 

“We can hardly wait to see what those data reveal. Hopefully, we can now settle the question of water worlds once and for all,” Kreidberg stated.