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New Martian valley network volume estimate consistent with ancient ocean and warm and wet climate
Howard, Alan D.; Luo, Wei; Cang, Xuezhi
The volume of Martian valley network (VN) cavity and the amount of water needed to create the cavity by erosion are of significant importance for understanding the early Martian climate, the style and rate of hydrologic cycling, and the possibility of an ancient ocean. However, previous attempts at estimating these two quantities were based on sel…
A Solar cycle correlation of coronal element abundances in Sun-as-a-star observations
Warren, Harry P.; Brooks, David H.; Baker, Deborah +1 more
The elemental composition in the coronae of low-activity solar-like stars appears to be related to fundamental stellar properties such as rotation, surface gravity, and spectral type. Here we use full-Sun observations from the Solar Dynamics Observatory, to show that when the Sun is observed as a star, the variation of coronal composition is highl…
Dynamic molecular oxygen production in cometary comae
Yao, Yunxi; Giapis, Konstantinos P.
Abundant molecular oxygen was discovered in the coma of comet 67P/Churyumov-Gerasimenko. Its origin was ascribed to primordial gaseous O2 incorporated into the nucleus during the comet's formation. This thesis was put forward after discounting several O2 production mechanisms in comets, including photolysis and radiolysis of …