Astronomers have discovered an Earth-sized exoplanet that is unlike any planet found before – one hemisphere is covered in molten lava, while the other may potentially be habitable. This extreme hot-and-cold dichotomy on such a small planet challenges current models of planetary formation and evolution, and raises intriguing questions about whether life could develop under such conditions.
Key Details About the Lava Exoplanet
The new exoplanet, dubbed TOI-1452 b, was spotted in data from NASA’s Transiting Exoplanet Survey Satellite (TESS) mission by a team of astronomers led by Charles Cadieux, a PhD student at the University of Montreal. Follow-up observations confirmed the discovery:
- LOCATION: Orbiting a Sun-like star (spectral type G) in the Ursa Major constellation, about 100 light years from Earth
- SIZE: Approximately 1.1 times the diameter of Earth
- ORBIT: Extremely tight orbit that completes every 11 hours, located incredibly close to its star
- HEMISPHERES: Permanently tidally locked, with one hemisphere perpetually facing the star and the other facing away into space
- Dayside hemisphere: Estimated >2000°C surface temp, completely covered by a lava ocean due to extreme heating
- Nightside hemisphere: Estimated -200°C surface temp, could potentially have more Earth-like conditions
“It’s a burnt, black landscape on one side and quite possibly a habitable, water landscape on the other side,” said Cadieux.
Why the Discovery Is Significant
Planets this small and close to their host stars are usually tidally locked, with one hot side and one cold side. But TOI-1452 b takes this to an extreme – the night and day sides are vastly different, making it effectively half lava world and half potentially-habitable.
“This planet is one of the coolest rocky planets that we have found that is this close to its star. All planets at these short orbital periods around Sun-like stars are basically lava planets but this one stuck out,” said lead researcher Charles Cadieux.
The reasons behind this strange dichotomy are unclear. Some possibilities that researchers will investigate further include:
- The planet could have a molten mantle that efficiently transfers heat to the dayside
- It may have exotic volcanic activity that resurfaces the dayside
- There could be exotic high-temperature materials like silicates in the lava
- The nightside could have a thick atmosphere that helps distribute heat
“There are still big open questions about the nature and origin of lava planets,” said Cadieux. Understanding TOI-1452 b will help answer these questions about these extreme exoplanet types.
Follow-Up Observations and Future Research
Now that the exoplanet has been identified, astronomers plan additional observations to better characterize its environment:
- Further spectroscopic study to analyze the lava composition and look for signatures of an atmosphere.
- Using the upcoming James Webb Space Telescope to potentially identify molecular signatures related to habitability on the nightside.
- Exploring whether the planet has an electromagnetic field that could shield the nightside.
- Modeling the planet’s formation, evolution, and complex atmosphere/interior heat transfer.
“The hemisphere we don’t see is an exciting mystery,” said researcher Kamen Todorov. “Is the hidden side still molten, or did it manage to lose more of its primordial heat and somehow end up with a solid surface?”
This discovery also bolsters the science case for a proposed NASA mission called the Extreme-Precision Radial Velocity (EPRV) planet hunter, which would enable more detailed study of rocky planets around nearby stars.
“Weird, wild planets like TOI-1452 b stretch our imagination. Environmental extremes in exoplanet science are helping us better understand how planetary systems form and evolve over time,” said Todorov.
Next Steps in the Search for Habitable Worlds
While TOI-1452 b itself is likely far too hot on its dayside to host life, some researchers speculate that a planet slightly farther out from its star could potentially have a strip of habitability between the extremes.
“Maybe some middling planet between the hot and cold could potentially sustain life,” suggests Cadieux.
Table 1 summarizes the potential habitability of different zones on TOI-1452 b if it was located at different distances from its host star:
| Planet Location | Dayside Surface Temp | Dayside Habitability | Nightside Surface Temp | Nightside Habitability |
|---|---|---|---|---|
| Current orbit | >2000°C | Uninhabitable | -200°C | Possibly habitable |
| 10% farther out | ~1000°C | Uninhabitable | 0°C | Potentially habitable |
| 20% farther out | ~500°C | Uninhabitable | > 0°C | Potentially habitable |
| 30% farther out | < 100°C | Potentially habitable | > 0°C | Potentially habitable |
While so far no planets have been found with conditions right for this hypothetical “ribbon of habitation,” astronomers are continuing the search. In particular, the developing field of exoplanet geoscience will be key for evaluating habitability.
“As rocky exoplanet datasets grow, we will be able to identify more exoplanets like TOI-1452 b whose extreme environments can teach us about the diversity and equilibria between planetary interior, surface and atmospheric processes,” said Todorov.
In the coming years, additional observations from missions like TESS and JWST, as well as next-generation extremely large telescopes, will likely reveal even more diverse exoplanet worlds – some perhaps even stranger than lava world TOI-1452 b.
“This hot, rocky world gives us a glimpse into the variety of exoplanets out there and insight into extreme planetary physics and formation,” summarized Cadieux. “Worlds like this motivate us toward the next discoveries.”
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