| Autor: |
Yo Kawamura, Tatsuya Yoshida, Naoki Terada, Yuki Nakamura, Shungo Koyama, Hiroki Karyu, Kaori Terada, Shotaro Sakai |
| Jazyk: |
angličtina |
| Rok vydání: |
2024 |
| Předmět: |
|
| Zdroj: |
The Astrophysical Journal, Vol 967, Iss 2, p 95 (2024) |
| Druh dokumentu: |
article |
| ISSN: |
1538-4357 |
| DOI: |
10.3847/1538-4357/ad3e7e |
| Popis: |
Terrestrial planets currently in the habitable zone around M dwarfs are estimated to have been in runaway greenhouse conditions for up to ∼1 Gyr due to the long-term pre-main-sequence phase of M dwarfs. These planets likely lose a significant portion of water during the pre-main-sequence phase owing to H _2 O photolysis followed by hydrogen and oxygen loss to space. However, the effects of H _2 O reproduction reactions and UV shielding by chemical products that reduce photolysis-induced water loss have yet to be estimated. Here, we apply a 1D photochemical model to a H _2 O-dominated atmosphere of an Earth-like planet around a pre-main-sequence M dwarf to estimate these effects. We find that water loss is suppressed by efficient H _2 O reproduction reactions and by UV shielding due to O _2 . The water loss rate decreases by several to several hundred times compared to that in previous studies, with the assumption that the water loss rate is limited by stellar X-ray and extreme-ultraviolet flux or hydrogen diffusion through the atmosphere. Our results imply that terrestrial planets currently in the habitable zone around M dwarfs are more likely to retain surface water than previously estimated. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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