Astronomers using NASA’s Hubble Space Telescope have observed the smallest exoplanet to have water vapor in its atmosphere. Planet GJ 9827d, which is only about twice the diameter of Earth, could be an example of potential planets with water-rich atmospheres in other parts of our galaxy. GJ 9827d was discovered by NASA’s Kepler space telescope in 2017. It orbits the red dwarf every 6.2 days. The star GJ 9827 is located 97 light years from Earth in the constellation Pisces.
However, it is too early to tell whether Hubble spectroscopically measured small amounts of water vapor in the hydrogen-rich atmosphere, or whether the planet’s atmosphere is mostly made up of water left over after the primordial hydrogen-helium atmosphere was evaporated by stellar radiation. If the planet is as hot as Venus (800 degrees Fahrenheit, 425 degrees Celsius), then it would definitely be an inhospitable and steamy world, with carbon dioxide dominating the atmosphere.
“Our observing program, led by principal investigator Ian Crossfield of the University of Kansas in Lawrence, Kansas, was designed specifically to not only detect molecules in the planet’s atmosphere, but also specifically look for water vapor. Any result would be exciting, regardless of whether water vapor is dominant or just a tiny species in a hydrogen-dominated atmosphere,” said lead author Pierre-Alexis Roy of the Trottier Institute for Exoplanet Research at the University of Montreal.
The Hubble program observed the planet during 11 transits (events in which the planet crossed its star) that lasted three years. During transits, starlight is filtered through the planet’s atmosphere and receives the spectral fingerprint of water molecules. If a planet has clouds, they are low enough in the atmosphere to not completely obscure Hubble’s view of the atmosphere, and the telescope is able to study water vapor above the clouds.
In total, scientists have discovered 85 new planets outside the solar system, the temperature on which makes them suitable for life, reports the Daily Mail. It is noted that all of them are larger than the Earth, the diameter of some is 1.4 times greater than that of the Earth, others – more than 40 times. According to the head of the study, each of the planets is in a separate system, some of them may consist of gas, and some may have a solid shell.
“Scientists at the University of Warwick have discovered an additional 85 exoplanets, planets outside our solar system… Like Earth, they are potentially at just the right distance from their stars to have a temperature that could support life, known as the habitable zone,” the paper states publication message.
What is known about the discovered celestial bodies is that they rotate around their stars more slowly than most exoplanets. According to preliminary data, one revolution takes from 20 to 700 days, compared to the standard 3–10 days. This suggests they are farther away from the star, which means cooler temperatures, the newspaper reports. Of the 85 exoplanets discovered, 60 are completely new discoveries, while the remaining 25 were discovered by independent teams that were already in NASA telescope data.