Skip to main content

James Webb discovers a new type of exoplanet: an exotic ‘steam world’

An artist’s conception of the “steam world” GJ 9827 d, shown in the foreground in blue.
An artist’s conception of the “steam world” GJ 9827 d, shown in the foreground in blue. NASA, ESA, Leah Hustak (STScI), Ralf Crawford (STScI)

Our solar system has a wide variety of planet types, from tiny rocky Mercury to huge puffy gas giant Jupiter to distant ice giant Uranus. But beyond our own system, there are even more types of exoplanet out there, including water worlds covered in ocean and where life could potentially thrive. Now, researchers using the James Webb Space Telescope have identified a new and exotic type of planet called a steam world, which has an atmosphere almost entirely composed of water vapor.

The planet, called GJ 9827 d, was examined by the Hubble Space Telescope earlier this year and had researchers so intrigued that they wanted to go back for a closer look using Webb. They found that the planet, which is around twice the size of Earth, had a very different atmosphere from the typical hydrogen and helium that is usually seen. Instead, it was full of hot steam.

Recommended Videos

“This is the first time we’re ever seeing something like this,” said researcher Eshan Raul of the University of Michigan in a statement. “To be clear, this planet isn’t hospitable to at least the types of life that we’re familiar with on Earth. The planet appears to be made mostly of hot water vapor, making it something we’re calling a ‘steam world.'”

To look at the planet’s atmosphere, the researchers used Webb’s Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument that can split light into different wavelengths to see what something is composed of in a technique called transmission spectroscopy. This is easier to do with lighter elements like hydrogen and helium, so being able to use this technique for a heavier element like water means scientists can now start to investigate more diverse planetary atmospheres.

“Now we’re finally pushing down into what these mysterious worlds with sizes between Earth and Neptune, for which we don’t have an example in our own solar system, are actually made of,” said fellow researcher Ryan MacDonald. “This is a crucial proving step towards detecting atmospheres on habitable exoplanets in the years to come.”

As this is such a new area of research, the discovery required new software written by the team so Raul, who is an undergraduate student, was the first person to see direct evidence that steam worlds existed.

“It was a very surreal moment,” said Raul, now a doctoral candidate at the University of Wisconsin-Madison. “We were searching specifically for water worlds because it was hypothesized that they could exist. If these are real, it really makes you wonder what else could be out there.”

The research is published in The Astrophysical Journal Letters.

Georgina Torbet
Georgina has been the space writer at Digital Trends space writer for six years, covering human space exploration, planetary…
James Webb captures gorgeous image of a Cosmic Tornado
The NASA/ESA/CSA James Webb Space Telescope observed Herbig-Haro 49/50, an outflow from a nearby still-forming star, in high-resolution near- and mid-infrared light with the NIRCam and MIRI instruments. The intricate features of the outflow, represented in reddish-orange color, provide detailed clues about how young stars form and how their jet activity affects the environment around them. A chance alignment in this direction of the sky provides a beautiful juxtaposition of this nearby Herbig-Haro object (located within our Milky Way) with a more distant, face-on spiral galaxy in the background.

The James Webb Space Telescope has captured another stunning image of space, this time showing the dramatic scenes around a baby star. Very young stars can throw off powerful jets of hot gas as they form, and when these jets collide with nearby dust and gas they form striking structures called Herbig-Haro objects.

This new image shows Herbig-Haro 49/50, located nearby to Earth at just 630 light-years away in the constellation Chamaeleon. Scientists have observed this object before, using the Spitzer Space Telescope, and they named the object the "Cosmic Tornado" because of its cone-like shape. To show the impressive powers of James Webb to capture objects like this one in exquisite detail, you can compare the Spitzer image from 2006 and the new James Webb image.

Read more
NASA’s Webb telescope peers straight at Saturn-like planets 130 light-years away
Saturn captured by the James Webb Space Telescope.

The James Webb Space Telescope is NASA's most precise and technically proficient equipment for observing the wonders of the universe. Astronomers rely on it to unravel the deepest secrets by peaking at distant solar systems and capturing planets like those in ours.

Much recently, the Webb Telescope was able to capture its first direct image of exoplanets nearly 130 light-years away from the Earth. The observatory seized images of four "giant" planets in the solar system of a distant star called HR 8799. This is a fairly young system formed roughly 30 million years ago, a timeline that dwarfs in comparison to our solar system's 4.6 billion years of age.

Read more
James Webb captures a stunning view of the dreamy Flame Nebula
Webb's image of the Flame Nebula

Our universe is host to many beautiful and fascinating objects, and we're lucky enough to be able to view many of them using high tech instruments like the James Webb Space Telescope. A new Webb image shows a new view of the gorgeous Flame Nebula, an emission nebula located in the constellation of Orion.

This nebula is a busy stellar nursery, with many new stars being formed there. But it isn't stars which researchers were interested in when they looked to the nebula -- in this case, they were studying objects called brown dwarfs. Bigger than most planets but smaller than a star, brown dwarfs are too small to sustain fusion in their cores, so they are often referred to as failed stars.

Read more