They capture water vapor in the atmosphere of planet GJ 9827d

2024-01-27 04:15:35

Using the Hubble Space Telescope, astronomers have observed the smallest exoplanet in whose atmosphere water vapor has been detected. At only about twice the diameter of Earth, planet GJ 9827d could be an example of the possible abundant existence of rocky, Earth-like planets with water-rich atmospheres elsewhere in our galaxy.

The discovery was made by a team led by Pierre-Alexis Roy, from the Trottier Institute for Exoplanet Research at the University of Montreal, Canada.

GJ 9827d is 97 light-years away from Earth. It was discovered by NASA’s Kepler space telescope in 2017. It completes one orbit around its star, GJ 9827, every 6.2 days. The star is reddish and smaller than the Sun.

Given that the planet, due to its proximity to the star, is as hot as Venus, at about 450 degrees Celsius, it is definitely an inhospitable world.

The abundance of water vapor detected remains to be clarified. There are several possibilities.

One of them is that the planet still has a primitive atmosphere, rich in hydrogen, as well as provided with water, which would make it a kind of mini-Neptune.

Another possibility is that it is a hotter version of Europa, a moon of Jupiter on which life could exist. The crust of that moon contains twice as much water as Earth.

Or perhaps the planet formed close to the star, and in that case the amount of water in its atmosphere must be modest.

Artist’s recreation of exoplanet GJ 9827d, the smallest of all exoplanets in whose atmospheres water vapor has been detected. This planet could be an example of the existence of numerous planets with water-rich atmospheres elsewhere in our galaxy. GJ 9827d is orbiting the star GJ 9827. (Illustration: NASA / ESA / Leah Hustak (STScI) / Ralf Crawford (STScI))

If GJ 9827d has a water-rich atmosphere, then the star must have formed at a much greater distance from its host star than the distance that separates it from it today. In the orbital strip that was its former location and where it formed, the temperature is cold and water is available in the form of ice. In this scenario, the planet would have then migrated closer to the star and received more radiation. The hydrogen heated up and escaped into space, or is still in the process of escaping. (Source: NCYT from Amazings)