{"id":40451,"date":"2026-03-11T21:11:37","date_gmt":"2026-03-11T20:11:37","guid":{"rendered":"https:\/\/karmaka.de\/?p=40451"},"modified":"2026-03-11T21:11:38","modified_gmt":"2026-03-11T20:11:38","slug":"shaken-not-stirred-inefficient-mixing-of-cm-and-ci-like-materials","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=40451","title":{"rendered":"Shaken, not stirred: inefficient mixing of CM- and CI-like materials<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Sarah E. Anderson, Pierre Vernazza, Miroslav Broz<\/p>\n\n\n\n<p>Astronomy &amp; Astrophysics manuscript no. aa57394-25, March 11, 2026<\/p>\n\n\n\n<p><a href=\"https:\/\/arxiv.org\/pdf\/2603.09749\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;A recent study suggests that CM chondrite-like planetesimals formed in the vicinity of Saturn, in a pressure bump outside the gap carved by proto-Jupiter. While a fraction of these objects was implanted into the asteroid belt as a consequence of Saturn&#8217;s growth, it remains unclear whether the scattered remainder could reach the ice-giant region and mix with more distant carbonaceous reservoirs. We test whether outward scattering during Saturn&#8217;s growth and migration can implant CM-like bodies onto long-lived orbits in the Uranus-Neptune region, where they could contaminate the CI reservoir. We performed N-body integrations of 100 km planetesimals launched from the outer edge of Jupiter&#8217;s gap, including gas drag and the gravitational perturbations of growing Jupiter and Saturn, with optional inclusion of a nearby ice-giant embryo. We explored a range of gas surface-density profiles and growth timescales. While Saturn&#8217;s growth efficiently scatters CM-like planetesimals, fewer than about 2 percent are implanted beyond 15 au, even under gas-rich conditions, because gas drag damps their eccentricities and drives them back toward their perihelia rather than allowing them to circularize at larger distances. Adding an ice-giant core modestly increases the outward reach (up to about 4 percent in the most gas-rich case), but Type-I migration further lowers perihelia, making long-term retention at large distances difficult. For a CM mass budget MCM,tot \u223c 1 M\u2295, this implies at most MCM \u2272 0.02\u20130.04 M\u2295 reaches 15-25 au, corresponding to a diluted mass fraction \u2272 (1\u20132) \u00d7 10\u22123 in the outer ring, hence negligible contamination of the CI reservoir. Combined with the distinct radial distributions of CM- and CI-like asteroids in the belt, these results imply limited mixing of carbonaceous reservoirs and isolation of the CI reservoir.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Sarah E. Anderson, Pierre Vernazza, Miroslav Broz Astronomy &amp; Astrophysics manuscript no. aa57394-25, March 11, 2026 PDF (OPEN ACCESS) &#8220;A recent study suggests that CM chondrite-like planetesimals formed in the vicinity of Saturn, in a&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,10,73],"tags":[3273,1809,4006,5007,105,3646,4370,3019,6415],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/40451"}],"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=40451"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/40451\/revisions"}],"predecessor-version":[{"id":40452,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/40451\/revisions\/40452"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=40451"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=40451"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=40451"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}