2020/08/01 by Zahra Essack, Sara Seager, Mihkel Pajusalu
Physics and Astronomy · #Achondrite #Albedo (alchemy) #Asteroid #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Basalt #Exoplanet #Geometric albedo #Lava #Planet #Reflection (computer programming) #Regolith #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.3847/1538-4357/ab9cba
published as ApJ 898, 2 (2020) · 18 pages, 14 figures, 4 tables, published in ApJ
openalex publication_date 2020/08/01 · arxiv created 2020/08/06 · arxiv updated 2020/08/07 · openalex created_date 2020/08/10 · openalex updated_date 2026/08/05
Abstract Hot super-Earths are exoplanets with short orbital periods (<10 days), heated by their host stars to temperatures high enough for their rocky surfaces to become molten. A few hot super-Earths exhibit high geometric albedos (>0.4) in the Kepler band (420–900 nm). We are motivated to determine whether reflection from molten lava and quenched glasses (a product of rapidly cooled lava) on the surfaces of hot super-Earths contribute to the observationally inferred high geometric albedos. We experimentally measure reflection from rough- and smooth-textured quenched glasses of both basalt and feldspar melts. For lava reflectance values, we use specular reflectance values of molten silicates from non-crystalline solids literature. Integrating the empirical glass reflectance function and non-crystalline solids reflectance values over the dayside surface of the exoplanet at secondary eclipse yields an upper limit for the albedo of a lava-quenched glass planet surface of ∼0.1. We conclude that lava planets with solid (quenched glass) or liquid (lava) surfaces have low albedos. The high albedos of some hot super-Earths are most likely explained by atmospheres with reflective clouds (or, for a narrow range of parameter space, possibly Ca/Al oxide melt surfaces). Lava planet candidates in TESS data can be identified for follow-up observations and future characterization.