Hot Earth or young Venus? A nearby transiting rocky planet mystery
Venus and Earth offer a startlingly different view of the evolution of a rocky planet, raising the question of why these two rocky worlds evolved so differently.
The recently discovered transiting rocky planet LP 890-9c (TOI-4306c, SPECULOOS-2c) is the key to this question. SPECULOOS-2c (1.367 + 0.055 -0.039 R_Earth) circles a nearby M6V star of relatively low activity (32 pc) in 8.46 days. SPECULOOS-2c receives 0.906 +/- 0.026 of the flux from modern Earth, putting it very close to the inner edge of the conservative habitable zone, where models differ sharply in their prediction of how long Earth-like planets can conserve their water.
Our atmosphere models show that the transmission spectra of observable species can tell the difference between a hot and humid Young Earth, a scorching rocky planet caught in a runaway greenhouse on the brink of total water loss, and an analogue of Venus. Distinguishing these scenarios from the planet’s spectra will provide key new insights into when a hot terrestrial planet loses its water and becomes a Venus.
SPECULOOS-2c is a prime target for observations with JWST. Observing it will also provide key information for predicting Earth’s long-term future.
L. Kaltenegger, RC Payne, Z. Lin, J. Kasting, L. Delrez
Comments: submitted ApJL
Subjects: Terrestrial and planetary astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2209.03105 [astro-ph.EP] (or arXiv:2209.03105v1 [astro-ph.EP] for this release)
By: Lisa Kaltenegger
[v1] Wed Sep 07 2022 12:40:01 AM UTC (902 KB)
Full article: https://arxiv.org/abs/2209.03105