Uncovering the Secrets of LP 890-9c: Could This Rocky Exoplanet Support Life?
Key Highlights :
The discovery of exoplanet LP 890-9c, located 98 light-years away, has sparked the curiosity of scientists around the world. This rocky exoplanet, orbiting a red dwarf star, is located near the inner edge of its star's habitable zone, suggesting that it could potentially support liquid water and life. But could this exoplanet be the key to unlocking the secrets of how planets like Earth can transform into inhospitable worlds like Venus?
New research led by Lisa Kaltenegger of the Carl Sagan Institute at Cornell University has modeled the possible climatic and atmospheric states that LP 890-9c could be in, and how the James Webb Space Telescope (JWST) could be used to distinguish between them. The team produced five different models describing what LP 890-9c might be like, ranging from an Earth-like planet but hotter, to a hellish Venus-like atmosphere with a suffocating carbon dioxide layer.
The planet's position in its planetary system is analogous to Venus' location in our solar system, which is also at the inner edge of the habitable zone. In principle, a planet at Venus' location can remain habitable, but at some point in its 4.5-billion-year history, Venus got trapped within the feedback loop of a runaway greenhouse effect. Any water Venus once had on its surface boiled away, and the planet was left with a thick carbon-dioxide atmosphere.
LP 890-9c could be different, though. For one, Venus does not have its own magnetic field to ward off the solar wind, the stream of charged particles flowing from the sun. This made it easier for the solar wind to carry away hydrogen atoms that were split from water molecules by ultraviolet light from the sun, thus depleting the planet of water. If LP 890-9c has a strong magnetic field, it may be able to ward off its star's stellar wind and hold onto the water vapor in its atmosphere.
A separate study led by Jonathan Gomez Barrientos of the California Institute of Technology shows that JWST would only need to observe three transits of LP 890-9c across the face of its host star to confirm a steamy, water-rich atmosphere; eight transits to gather enough data to determine whether LP 890-9c is more like Venus; and 20 transits to find evidence of the still-habitable hot Earth scenario. Since the planet transits its star every 8.5 Earth days, the measurements could in principle take just six months to make.
The findings of this research could teach us something fundamental about how rocky planets evolve with increasing starlight, and about what will one day happen to Earth. Studying a planet other than Venus that has already gone through this phase, or perhaps even resisted it for now, will help inform us about Earth's own future.
The scientists reported their results in two papers published June 21 in the Monthly Notices of the Royal Astronomical Society. With the help of the James Webb Space Telescope, astronomers may soon have the answer to the question of whether LP 890-9c could potentially support life, and in the process, uncover the secrets of how planets like Earth can transform into inhospitable worlds like Venus.
