NASA’s James Webb Space Telescope has helped astronomers discover a strange rocky planet in the distance that shows hints of an atmosphere rich in water vapor despite its proximity to its star.
Researchers, including those from NASA’s Goddard space center, say the exoplanet known as GJ 486 b is too close to its star to be within the habitable zone, with a surface temperature of about 800 degrees Fahrenheit.
The planet, located about 26 light-years away in the constellation Virgo, is about 30 percent larger than Earth and nearly three times as massive, meaning it is a rocky world with stronger gravity than Earth.
Orbits GJ 486 b a red dwarf star, which completes a revolution in just under 1.5 Earth days, and is probably tidally locked, with a permanent day side and a permanent night side.
However, signs of water vapor associated with the planet could indicate that it has an atmosphere despite its scorching temperature and proximity to its star, the study, published in The Astrophysical Journal Letters, noted.
Previous studies have shown that red dwarf stars are cool enough that planets near them have tight orbits to stay warm enough to host liquid water to create a habitable zone for life.
Although water vapor has been seen on gaseous exoplanets orbiting these stars before, no atmosphere has definitely been found around a rocky exoplanet.
However, researchers warn after the new discovery that the water vapor could be on the star itself, and not from the planet at all.
“Water vapor in the atmosphere of a hot rocky planet could be a major breakthrough for exoplanet science. But we have to be careful and make sure the star is not the culprit,” said study author Kevin Stevenson from Johns Hopkins University in the US.
“We see a sign, and it’s definitely water. But we still can’t tell if that water is part of the planet’s atmosphere, meaning the planet yes atmosphere, or if we’re just seeing a watermark coming from the star,” explained study lead author Sarah Moran from the University of Arizona in Tucson.
Scientists saw the star crossing its star, crossing in front of the red dwarf from Earth’s point of view.
If the planet has an atmosphere, then when it transits, the starlight would filter through those gases, printing a fingerprint in the light that allows astronomers to decode its composition.
Decoding the planet’s chemical composition during its transit, astronomers concluded that water vapor was the most likely source of the planet’s signal.
While the water vapor could indicate the presence of an atmosphere, researchers say the signals likely come from the star.
There are also similar reports of water vapor in our own Sun that sometimes occurs in sunspots.
Since GJ 486 bi’s host star is much cooler than the Sun, scientists suspect that more water vapor could concentrate within its star spots.
This may have created a signal mimicking a planetary atmosphere, they say.
Because an atmosphere of water vapor could gradually erode due to heating from the star, even if an atmosphere were present, the researchers say it would have to be constantly replenished by volcanoes from inside the planet.
They say further observations are needed to narrow down the amount of water present if there is conclusive evidence.
Researchers hope to study data from Webb’s multiple instruments to definitively determine the presence of water vapor.
“It is connecting multiple tools together that will really pin down whether or not the planet has an atmosphere,” said Dr. Stevenson.