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Cold Lava Exoplanet Found With Atmosphere
Confirmed
In Short: The exoplanet orbits its star in less than one Earth day, challenging previous assumptions about lava worlds and their atmospheres.
Researchers from the United States, United Kingdom, China, and Spain have found evidence suggesting that HD 3167 b, an Earth-sized lava world, might have an atmosphere despite its cooler temperature.
The discovery of HD 3167 b's potential atmosphere adds to the growing number of similar lava worlds with substantial atmospheres.
Scientists have been working to understand the conditions under which planets can retain atmospheres, a key factor in planetary habitability.
The cosmic shoreline describes the boundary between rocky worlds that can retain atmospheres and those that cannot.
Some lava worlds, however, lie much closer to their stars than the boundary predicts and still have atmospheres.
Researchers developed a model showing how lava-covered planets close to their stars can hold onto their atmospheres, which could help guide the search for life beyond our solar system.
By slowing the release of atmospheric gases, lava can allow atmospheric replenishment to keep pace with losses caused by stellar radiation, preserving an atmosphere for billions of years.
What this adds
The discovery of HD 3167 b's potential atmosphere challenges previous assumptions about the conditions necessary for a planet to retain an atmosphere.
The research suggests that the traditional cosmic shoreline boundary may need to be reevaluated to account for the atmospheric retention capabilities of cooler lava worlds.
What's confirmed
- Researchers from the United States, United Kingdom, China, and Spain have found evidence suggesting that HD 3167 b, an Earth-sized lava world, might have an atmosphere despite its cooler temperature.
- The discovery of HD 3167 b's potential atmosphere adds to the growing number of similar lava worlds with substantial atmospheres.
- Scientists have been working to understand the conditions under which planets can retain atmospheres, a key factor in planetary habitability.
- The cosmic shoreline describes the boundary between rocky worlds that can retain atmospheres and those that cannot.
- Some lava worlds, however, lie much closer to their stars than the boundary predicts and still have atmospheres.
- Researchers developed a model showing how lava-covered planets close to their stars can hold onto their atmospheres, which could help guide the search for life beyond our solar system.
- By slowing the release of atmospheric gases, lava can allow atmospheric replenishment to keep pace with losses caused by stellar radiation, preserving an atmosphere for billions of years.
What's still developing
- But while it has been long known that lava worlds on with higher temperatures have atmospheres, “colder” lava worlds have been found to lack atmospheres.
- They made this discovery through observing the exoplanet’s secondary eclipse, which is when it is observed as it passes behind its star.
- When JWST observed HD 3167 b’s secondary eclipse, the exoplanet’s surface was found to be much cooler than previously hypothesized, with the researchers noting this could mean its heat from the dayside is redistributed to the night side.
- “Despite how inhospitable they are for life, we’re also interested in studying these kinds of planets because we think early Earth might have looked a lot like a lava world,” said Brandon Park Coy, who is a PhD student in the Department of the Geophysical Sciences at the University of Chicago and lead author of the study.
- Exoplanets continue to challenge our understanding of planetary formation, evolution, and whether they might be able to support life as we know it.
- Scientists often use planets in our solar system as analogs for exoplanets, studying exoplanets with extremely short orbital periods forces scientists to constantly rethink our understanding of what planets can withstand during their lifetimes.
- One such type of exoplanet that has entered the foray in recent years are “lava world” exoplanets, and especially lava exoplanets that orbit dangerously close to their stars.
- Now, an internation team of researchers might have inched our way to solving that conundrum, as they examine an Earth-sized lava world orbiting its star in less than one Earth day.
- “These lava worlds have pointed to something being wrong with the cosmic shoreline boundary, but we’ve found a way for them to preserve their atmospheres by proposing a new regime beyond it,” said lead study author Barron Nguyen, a graduate student in the lab of Laura Schaefer at the Stanford Doerr School of Sustainability.
- “Where the shoreline boundary is between airless worlds and those capable of sustaining an atmosphere has been a major open question in planetary science,” said Schaefer, the study’s senior author and an assistant professor of Earth and planetary sciences in the Doerr School of Sustainability.
- Despite that extreme location, observations from the James Webb Space Telescope in 2024 showed that 55 Cancri e has a remarkably thick atmosphere.
- Between the traditional shoreline and this sandbar lies what they call the “airless valley.” Planets there orbit close enough to lose their atmospheres, yet cool and solidify too quickly after formation to replace the escaping gas.