2010/07/19 by Robert A. Marcus, Robert Marcus, Dimitar Sasselov +2 · 86 citations
Physics and Astronomy · #Astro and Planetary Science #Astrobiology #Astrophysics #Environmental science #Exoplanet #Geochemistry #Geology #Geomorphology #Mantle (geology) #Physics #Planet #Scientific Research and Discoveries #Snow #Snow line #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.1088/2041-8205/719/1/l45
published in The Astrophysical Journal Letters 719(1), L45-L49 (IOP Publishing) · 9 pages, 4 figures, Accepted for publication in ApJ Letters
arxiv created 2010/07/19 · openalex publication_date 2010/07/21 · arxiv updated 2015/05/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Water-rich super-Earth exoplanets are expected to be common. We explore the effect of late giant impacts on the final bulk abundance of water in such planets. We present the results from smoothed particle hydrodynamics simulations of impacts between differentiated water(ice)-rock planets with masses between 0.5 and 5 M ⊕ and projectile to target mass ratios from 1:1 to 1:4. We find that giant impacts between bodies of similar composition never decrease the bulk density of the target planet. If the commonly assumed maximum water fraction of 75 wt% for bodies forming beyond the snow line is correct, giant impacts between similar composition bodies cannot serve as a mechanism for increasing the water fraction. Target planets either accrete materials in the same proportion, leaving the water fraction unchanged, or lose material from the water mantle, decreasing the water fraction. The criteria for catastrophic disruption of water-rock planets are similar to those found in previous work on super-Earths of terrestrial composition. Changes in bulk composition for giant impacts onto differentiated bodies of any composition (water rock or rock iron) are described by the same equations. These general laws can be incorporated into future N -body calculations of planet formation to track changes in composition from giant impacts.