2020/02/18 by Christopher Spalding, Spalding, Christopher, Fred C. Adams +1
Earth and Planetary Sciences · Physics and Astronomy · #Astro and Planetary Science #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Geology and Paleoclimatology Research #Planetary Science and Exploration #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2002.07847
openalex publication_date 2020/02/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The planet Mercury possesses an anomalously large iron core, and a\ncorrespondingly high bulk density. Numerous hypotheses have been proposed in\norder to explain such a large iron content. A long-standing idea holds that\nMercury once possessed a larger silicate mantle which was removed by a giant\nimpact early in the the Solar system's history. A central problem with this\nidea has been that material ejected from Mercury is typically re-accreted onto\nthe planet after a short (~Myr) timescale. Here, we show that the primordial\nSolar wind would have provided sufficient drag upon ejected debris to remove\nthem from Mercury-crossing trajectories before re-impacting the planet's\nsurface. Specifically, the young Sun likely possessed a stronger wind, fast\nrotation and strong magnetic field. Depending upon the time of the giant\nimpact, the ram pressure associated with this wind would push particles outward\ninto the Solar system, or inward toward the Sun, on sub-Myr timescales,\ndepending upon the size of ejected debris. Accordingly, the giant impact\nhypothesis remains a viable pathway toward the removal of planetary mantles,\nboth on Mercury and extrasolar planets, particularly those close to young stars\nwith strong winds.\n