Astronomers have discovered a world that they believe has ideal conditions for a thick atmosphere and an ocean half the size of the Atlantic Ocean.
The Exoplanet — a world that orbits a star other than the sun — is LHS 1140 b, and is located about 48 light-years from Earth, in the constellation Cetus. The planet is slightly less than twice the size of Earth.
A team of scientists pointed out that James Webb Space Telescope at LHS 1140 b twice in December 2023. Using a special instrument called a spectrograph on the powerful telescope, which is a collaboration between NASA and its European and Canadian room counterparts they looked for signs of an atmosphere.
“LHS 1140 b is one of the best small exoplanets in the habitable zone that can support a thick atmosphere,” said Ryan MacDonald, co-author of the exoplanet study at the University of Michigan, in a rack“and we may have found evidence of air on this world.”
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The James Webb Space Telescope has observed exoplanet LHS 1140 b. It could be an icy world similar to Jupiter’s moon Europa (left), but it could also have a large ocean pointed toward its star.
Credit: B. Gougeon / University of Montreal illustration
Exoplanet hunters have come up with names for different types of planets. Many of the known worlds orbit their host stars in tight circles. Smaller planets are usually divided into two groups, known as super-Earths and mini NeptunesWhile both types are larger than Earth and smaller than Neptune, super-Earths can be up to 1.75 times the size of our home planet, while mini-Neptunes are two to four times the size of Earth.
The team’s goal was to determine whether LHS 1140 b was a hydrogen-rich mini-Neptune or a scaled-up version of Earth. covered with water and iceTheir research immediately ruled out mini-Neptune, because LHS 1140 b lacked the signature of a large, bulging atmosphere. That means the exoplanet could be rocky and have other similarities to our planet.
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“But can we say anything about the atmospheric composition of this super-Earth?” MacDonald said on X, formerly Twitter. “That’s where it gets really exciting.”
The researchers’ analysis provided possible evidence that the planet has a thick, nitrogen-rich atmosphere like Earth’s, which 78 percent nitrogenThe result of the study, accepted for publication in The letters of the astrophysical journalcomes from a technique called transmission spectroscopy.
This method studies starlight filtered through the planet’s atmosphere. Molecules in the atmosphere absorb certain wavelengths of light, or colors. By splitting the light into its basic parts like a prism — a rainbow — astronomers can detect which segments of light are missing and figure out the composition of an atmosphere.
LHS 1140 b orbits a red dwarf star — a much smaller, colder star than the sun — at a distance that would likely cause the planet’s surface to be frozen. But if LHS 1140 b had an atmosphere, the world could experience a greenhouse effect, making a liquid ocean possible. The team also found that the exoplanet has less mass than expected, suggesting that 10 to 20 percent of it could be water weight.
“We may have found evidence of air on this world.”
Most astronomers agree that it is important to know what is happening in space. the atmosphere of another planet is crucial in the search for habitable worlds. NASA has playfully called Earth’s atmosphere its “security blanket”: without it, the type of life that thrives here wouldn’t exist. This cocoon traps oxygen in the air and filters out harmful ultraviolet radiation from the sun, keeping our world warm. It also creates pressure that allows liquid water to exist on the surface.
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Scientists have found traces of atmospheres around many exoplanets over the past 20 years, but they are all gas giant planetslike it Jupiterwith an envelope composed mostly of hydrogen. The hunt for an Earth-like world wrapped in a protective atmosphere has eluded astronomers until now, but Webb has recently helped scientists find candidates, such as 55 Cancer and or GJ486banother exoplanet study co-authored by MacDonald.
The LHS 1140 b team’s analysis suggests that this exoplanet is an icy world with a bull’s-eye ocean about 2,500 miles wide on the side that always faces its star. The surface temperature at the center of the ocean could even be close to a refreshing 68 degrees Fahrenheit.
“We will likely need years of additional observations to guarantee a concrete detection of an atmosphere on LHS 1140b,” MacDonald said at X, “but it is promising that the initial exploration is paying off!”