LINK<\/strong><\/a><\/p>\n\n\n\n“All asteroid spins evolve due to collisions. Geophysical analysis (Mao and McKinnon 2018b) implies Ceres might have been modestly despun (by ~6.5%) by impacts. Vesta\u2019s postaccretion rotation rate, before the formation of the Veneneia and Rheasilvia basins, has also been proposed to have been higher (by ~6%) than today (Fu et al. 2014). We have designed Monte Carlo simulations to investigate Ceres\u2019 and Vesta\u2019s plausible spin evolution by impacts. We use the main belt asteroid size\u2013frequency distribution, Ceres\u2019 and Vesta\u2019s cratering records, and their present\u2010day impact velocity probability distributions to quantify possible spin histories. We consider dynamical effects from escaping ejecta, adopt mass\u2010velocity scaling laws for two endmember surface materials (porous and nonporous), and track potential catastrophic disruptions. Results show that Ceres\u2019 spin period likely changed by a fraction of an hour (up or down) compared with its \u201cinitial,\u201d accretional spin, mostly due to large impacts. Different surface materials do not yield statistically distinguishable final spin distributions, but imply opposite crustal evolutions where Ceres loses\/accretes mass, depending on surface porosity; as much as several 100 m worth of exogenous material, globally averaged, can be accreted if the surface remains porous. Vesta\u2019s final Monte Carlo spin distribution is more concentrated around its \u201cinitial\u201d value, possibly implying a more relict spin state than Ceres. However, explicitly modeling the angular momentum changes wrought by Vesta\u2019s two existing planetary\u2010scale impact basins shows that their formation alone can account for Vesta\u2019s proposed spindown, although spinup is a much more likely outcome because of the scale and location of the impacts.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Xiaochen Mao, William B. McKinnon Meteoritics & Planetary ScienceVersion of Record online: 05 December 2020 LINK “All asteroid spins evolve due to collisions. Geophysical analysis (Mao and McKinnon 2018b) implies Ceres might have been modestly…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[167,1700,186],"tags":[1868,1501,2747,1872],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25438"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=25438"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25438\/revisions"}],"predecessor-version":[{"id":25439,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25438\/revisions\/25439"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=25438"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=25438"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=25438"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}