Plate Nº 95 · recorded October 10, 2026
Space & AstronomyReported finding
Webb Telescope Detects Atmosphere on Scorching Lava World HD 3167 b
The James Webb Space Telescope has detected strong evidence of an atmosphere on the rocky lava world HD 3167 b — 154 light-years away and the coolest yet found with such signs.
By Elena Vasquez3 min read654 words
In brief
- HD 3167 b is a rocky super-Earth 154 light-years away that orbits its star every 24 hours.
- The findings appeared October 7, 2026 in The Astrophysical Journal Letters, led by Brandon Park Coy of the University of Chicago.
- The team used mid-infrared secondary eclipse observations to estimate the planet's dayside temperature.
- HD 3167 b is the coolest of five lava worlds found so far with evidence of an atmosphere.
- The result is the first from a 10-planet survey led by Megan Weiner Mansfield of the University of Maryland.
The James Webb Space Telescope has detected strong evidence of an atmosphere around HD 3167 b, a rocky super-Earth 154 light-years from Earth that circles its star every 24 hours, according to a study published October 7, 2026 in The Astrophysical Journal Letters.
The detection puts HD 3167 b on a short roster of rocky worlds with measured atmospheres. It is the coolest lava world yet found with such evidence.
Why is the detection surprising?
Intuition says a rocky planet hugging its star should be stripped bare. Stellar winds batter it. High-energy photons pummel its surface.
"What's so surprising is that the closer a rocky planet orbits its star, the harder it should be to have an atmosphere, because it's bombarded by stellar wind and gets more high-energy photons from the star," said Edwin Kite, an associate professor of geophysical sciences at the University of Chicago and a co-author of the study.
Kite added that such planets are not candidates for life, "but by studying them, we can say something about the processes that matter for other rocky worlds."
How do you spot an atmosphere on a planet you cannot resolve?
The team used a technique called secondary eclipse spectroscopy. When HD 3167 b slipped behind its star, they measured how much mid-infrared light vanished. That drop reveals how much heat radiates from the dayside.
A bare rock should glow at the maximum temperature predicted by its distance from the star and its reflectivity. HD 3167 b came in noticeably cooler than that ceiling — a sign that something is moving warmth to the nightside or reflecting it away. Both jobs belong to atmospheres.
Lead author Brandon Park Coy, a graduate student in Kite's lab, explained the reasoning. On Venus, the day and night sides share nearly identical temperatures. If a faraway planet shows the same flattened temperature profile, gas or clouds are likely responsible.
What might the atmosphere contain?
The team has not pinned down the chemistry. They suspect a silicate-rich mixture, similar in composition to Earth's mantle, since the surface is molten rock. Earlier work predicted only vaporized rock in the gas. Newer hints suggest heavier molecules may dominate.
Possible ingredients include:
- Carbon dioxide
- Water vapor
- Carbon monoxide
- Vaporized silicates
Coy called the composition "still up in the air" and said new Webb observations are planned.
Why study a world that cannot host life?
Two motivations drive the research. First, HD 3167 b helps locate a thermal boundary. Five lava worlds have now shown evidence of atmospheres, and HD 3167 b is the coolest of the group. The team's survey targets the critical temperature at which rocky planets either retain or lose their atmospheres.
Second, the planet may serve as a stand-in for baby Earth. Researchers believe the young Earth was itself a magma ocean — a fully liquid surface that cooled over the first few million years after formation. Studying lava worlds lets scientists test which conditions held then.
"We're interested in studying these kinds of planets because we think early Earth might have looked a lot like a lava world," Coy said.
What comes next?
The result is the first from a survey of 10 ultra-hot lava worlds led by Megan Weiner Mansfield, now at the University of Maryland. The program aims to find the temperature threshold at which atmospheres appear and disappear.
If a clean threshold emerges, scientists can predict which rocky planets elsewhere are likely to hold their gas — and therefore liquid water. HD 3167 b sits squarely inside that search. Additional Webb time is planned to pin down the chemistry and test whether silicate clouds really cap the dayside.
Among more than 6,300 cataloged exoplanets, only a handful of rocky worlds have shown atmospheres. HD 3167 b is now one of them, and the coolest lava world yet found with evidence of one.
via news.uchicago.edu (Original)
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