Hubble Spots Water Vapor in Small Exoplanet's Atmosphere

'Astronomers using NASA's Hubble Space Telescope observed the smallest exoplanet where water vapor has been detected in the atmosphere,' writes SciTechDaily.

'At only approximately twice Earth's diameter, the planet GJ 9827d could be an example of potential planets with water-rich atmospheres elsewhere in our galaxy.'

'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,' said team member Björn Benneke of the Trottier Institute for Research on Exoplanets at Université de Montréal. 'This is an important step toward determining the prevalence and diversity of atmospheres on rocky planets.'

'Water on a planet this small is a landmark discovery,' added co-principal investigator Laura Kreidberg of Max Planck Institute for Astronomy in Heidelberg, Germany. 'It pushes closer than ever to characterizing truly Earth-like worlds.'

However, it remains too early to tell whether Hubble spectroscopically measured a small amount of water vapor in a puffy hydrogen-rich atmosphere, or if the planet's atmosphere is mostly made of water, left behind after a primeval hydrogen/helium atmosphere evaporated under stellar radiation... Because the planet is as hot as Venus, at 800 degrees Fahrenheit, it definitely would be an inhospitable, steamy world if the atmosphere were predominantly water vapor...

'Observing water is a gateway to finding other things,' said Thomas Greene, astrophysicist at NASA's Ames Research Center in California's Silicon Valley. 'This Hubble discovery opens the door to future study of these types of planets by the James Webb Space Telescope.

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