A "mini-Neptune," the most frequent sort of planet outside of our solar
system, was examined closely for the first time by the James Webb Space
Telescope, which discovered evidence of water.
The exoplanet GJ 1214b, a mini-Neptune planet orbiting a star around 40
light-years from Earth, has now been seen through the clouds. Mini-Neptunes
are a frequent sort of planet in our galaxy, resembling a scaled-down
counterpart of the known gas giant; but, since there isn't one in our solar
system, these worlds have mostly remained a source of scientific
fascination.
Thick cloud cover prevented scientists from making previous views of the
faraway planet, but the powerful James Webb Space Telescope's (JWST)
infrared thermal vision allowed them to discover a fresh perspective through
the mist. GJ 1214b possesses a steamy atmosphere, suggesting that it
formerly existed as a potential "water world," according to the findings,
which were reported on May 10 in the journal Nature(opens in new tab).
Rob Zellem, an exoplanet researcher at NASA's Jet Propulsion Lab, said in a
statement
that for over ten years, the only thing we actually knew about this planet
was that its atmosphere was clouded or hazy. As the planet went through its
orbit, the researchers utilized JWST's Mid-Infrared Instrument (MIRI) to map
the planet's temperature. By collecting data on the planet's day and night
sides, they were able to determine its composition.
On GJ 1214b, the temperature changed significantly from day to night,
reaching a maximum of 535 degrees Fahrenheit (280 degrees Celsius) during
the day and then dropping by more than 100 degrees F at night. A temperature
differential of 100 degrees would be equivalent to a day on Earth with
scorching heat during the day and a snowstorm overnight. This large
temperature change on GJ 1214b suggests that the atmosphere of the planet
must include more than simply light hydrogen molecules, such as water or
methane. Given that the atmosphere differs from what the star is comprised
of, scientists believe that this discovery offers an intriguing hint about
the planet's past.
GJ 1214b "either lost a lot of hydrogen, if it started with a hydrogen-rich
atmosphere, or it was formed from heavier elements to begin with — more icy,
water-rich material," lead research author
Eliza Kempton, an astronomer at the University of Maryland, said in a statement. "The
simplest explanation, if you find a very water-rich planet, is that it
formed farther away from the host star," she continued.
Although there is still plenty that astronomers don't know about GJ 1214b,
they anticipate seeing additional mini-Neptunes with JWST soon. They want to
determine a "consistent story" for how mini-Neptunes are made and how this
specific one arrived there with so much water, according to Kempton.
