2024/08/12 by Ana H. Lobo, Aomawa L. Shields, Lobo, Ana H +1 · 2 citations
Engineering · Physics and Astronomy · #Astro and Planetary Science #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Space Exploration and Technology #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2408.05951
openalex publication_date 2024/08/12 · openalex created_date 2024/09/10 · openalex updated_date 2026/07/28
M- and K-dwarf stars make up 86% of the stellar population and host many promising astronomical targets for detecting habitable climates in the near future. Of the two, M dwarfs currently offer greater observational advantages and are home to many of the most exciting observational discoveries in the last decade. But K dwarfs could offer even better prospects for detecting habitability by combining the advantage of a relatively dim stellar flux with a more stable stellar environment. Here we explore the climate regimes that are possible on Earth-like synchronous planets in M- and K-dwarf systems, and how they vary across the habitable zone. We focus on surface temperature patterns, water availability, and implications for habitability. We find that the risk of nightside cold-trapping decreases with increased orbital radius and is overall lower for K-dwarf planets. With reduced atmospheric shortwave absorption, K-dwarf planets have higher dayside precipitation rates and less day-to-night moisture transport, resulting in lower nightside snow rates. These results imply a higher likelihood of detecting a planet with a moist dayside climate in a habitable "eyeball" climate regime orbiting a K-dwarf star. We also show that "terminator habitability" can occur for both M- and K-dwarf land planets, but would likely be more prevalent in M-dwarf systems. Planets in a terminator habitability regime tend to have slightly lower fractional habitability, but offer alternative advantages including instellation rates more comparable to Earth in regions that have temperatures amenable to life.