Skip to main content

James Webb detects water vapor in rocky planet’s atmosphere — maybe

The hunt for habitable exoplanets is on, and with the James Webb Space Telescope, we finally have a tool that can not only detect the presence of a planet in another star system, but can also look at the composition of its atmosphere. That ability will eventually allow us to find Earth-like planets wthat are good candidates for searching for life, but measuring the atmosphere of something so far away isn’t an easy matter.

Webb recently saw exciting signs in the form of water vapor detected in the vicinity of the exoplanet GJ 486 b. That could indicate the presence of water in its atmosphere, but it could also be from another source: the outer layer of the planet’s host star. Researchers are working through the data and hope to use another of Webb’s instruments to make the final call.

This artist concept represents the rocky exoplanet GJ 486 b, which orbits a red dwarf star that is only 26 light-years away in the constellation Virgo. By observing GJ 486 b transit in front of its star, astronomers sought signs of an atmosphere. They detected hints of water vapor. However, they caution that while this might be a sign of a planetary atmosphere, the water could be on the star itself – specifically, in cool starspots – and not from the planet at all.
This artist’s concept represents the rocky exoplanet GJ 486 b, which orbits a red dwarf star that is only 26 light-years away in the constellation Virgo. By observing GJ 486 b transit in front of its star, astronomers sought signs of an atmosphere. They detected hints of water vapor. However, they caution that while this might be a sign of a planetary atmosphere, the water could be on the star itself and not from the planet at all. ILLUSTRATION: NASA, ESA, CSA, Joseph Olmsted (STScI), Leah Hustak (STScI)

The planet GJ 486 b is rocky, a bit larger than Earth, and more massive, so it would have heavier gravity than we experience. And the star it orbits is quite different from our sun, as it is a type called a red dwarf, which is a dim, cool star that is approaching the end of its life. The planet is close enough to the star, orbiting in just 1.5 days, that its surface temperature would be around 800 degrees Fahrenheit, so it isn’t in the habitable zone where liquid water can exist on the surface.

However, Webb’s NIRSpec instrument detected water vapor, which could mean that the planet does have an atmosphere even though it’s so close to its star.

“We see a signal and it’s almost certainly due to water. But we can’t tell yet if that water is part of the planet’s atmosphere, meaning the planet has an atmosphere, or if we’re just seeing a water signature coming from the star,” explained Sarah Moran of the University of Arizona, lead author of the research, in a statement.

The reason that the star could be the source of the water vapor is that there are cool spots on the star’s surface, similar to the sunspots seen on our sun. The cool areas around these regions are more likely to collect water vapor compared to the hot regions around them, so there could be enough water vapor to give a signal to Webb’s instrument.

Finding water in the atmosphere of this rocky planet would be exciting since astronomers haven’t seen this before, and it could help to find habitable exoplanets in the future. But to be sure of the source of the water vapor, the researchers need to make more measurements using Webb’s NIRISS and MIRI instruments.

“Water vapor in an atmosphere on a hot rocky planet would represent a major breakthrough for exoplanet science,” said fellow researcher Kevin Stevenson of the Johns Hopkins University Applied Physics Laboratory. “But we must be careful and make sure that the star is not the culprit.”

The research will be published in The Astrophysical Journal Letters.

Editors' Recommendations

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
James Webb observes merging stars creating heavy elements
This image from Webb’s NIRCam (Near-Infrared Camera) instrument highlights GRB 230307A’s kilonova and its former home galaxy among their local environment of other galaxies and foreground stars. The neutron stars were kicked out of their home galaxy and travelled the distance of about 120,000 light-years, approximately the diameter of the Milky Way galaxy, before finally merging several hundred million years later.

In its earliest stages, the universe was composed mostly of hydrogen and helium. All of the other, heavier elements that make up the universe around us today were created over time, and it is thought that they were created primarily within stars. Stars create heavy elements within them in the process of fusion, and when these stars reach the ends of their lives they may explode in supernovas, spreading these elements in the environment around them.

That's how heavier elements like those up to iron are created. But for the heaviest elements, the process is thought to be different. These are created not within stellar cores, but in extreme environments such as the merging of stars, when massive forces create exceedingly dense environments that forge new elements.

Read more
Researchers discover a 320-mph jet stream around Jupiter’s equator
This image of Jupiter from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) shows stunning details of the majestic planet in infrared light. In this image, brightness indicates high altitude. The numerous bright white "spots" and "streaks" are likely very high-altitude cloud tops of condensed convective storms. Auroras, appearing in red in this image, extend to higher altitudes above both the northern and southern poles of the planet. By contrast, dark ribbons north of the equatorial region have little cloud cover. In Webb’s images of Jupiter from July 2022, researchers recently discovered a narrow jet stream traveling 320 miles per hour (515 kilometers per hour) sitting over Jupiter’s equator above the main cloud decks.

The James Webb Space Telescope might be best known for its study of extremely distant galaxies, but it is also used for research on targets closer to home, like planets within our solar system. Last year, the telescope captured a stunning image of Jupiter as seen in the infrared wavelength, and now scientists who have been working on this data have published some of their findings about the planet -- including a brand-new feature that they identified in its atmosphere.

This image of Jupiter from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) shows stunning details of the majestic planet in infrared light. In Webb’s images of Jupiter from July 2022, researchers recently discovered a narrow jet stream traveling 320 miles per hour (515 kilometers per hour) sitting over Jupiter’s equator above the main cloud decks. NASA, ESA, CSA, STScI, Ricardo Hueso (UPV), Imke de Pater (UC Berkeley), Thierry Fouchet (Observatory of Paris), Leigh Fletcher (University of Leicester), Michael H. Wong (UC Berkeley), Joseph DePasquale (STScI)

Read more
James Webb captures a gorgeous stellar nursery in nearby dwarf galaxy
This new infrared image of NGC 346 from NASA’s James Webb Space Telescope’s Mid-Infrared Instrument (MIRI) traces emission from cool gas and dust. In this image blue represents silicates and sooty chemical molecules known as polycyclic aromatic hydrocarbons, or PAHs. More diffuse red emission shines from warm dust heated by the brightest and most massive stars in the heart of the region. Bright patches and filaments mark areas with abundant numbers of protostars. This image includes 7.7-micron light shown in blue, 10 microns in cyan, 11.3 microns in green, 15 microns in yellow, and 21 microns in red (770W, 1000W, 1130W, 1500W, and 2100W filters, respectively).

A gorgeous new image from the James Webb Space Telescope shows a stunning sight from one of our galactic neighbors. The image shows a region of star formation called NGC 346, where new stars are being born. It's located in the Small Magellanic Cloud, a dwarf galaxy that is a satellite galaxy to the Milky Way.

The star-forming region of the Small Magellanic Cloud (SMC) was previously imaged by the Hubble Space Telescope in 2005, but this new image gives a different view as it is taken in the infrared wavelength by Webb instead of the optical light wavelength used by Hubble.

Read more