{"id":25735,"date":"2021-01-18T10:37:29","date_gmt":"2021-01-18T09:37:29","guid":{"rendered":"http:\/\/karmaka.de\/?p=25735"},"modified":"2021-01-18T10:37:30","modified_gmt":"2021-01-18T09:37:30","slug":"presolar-stardust-in-highly-pristine-cm-chondrites-asuka-12169-and-asuka-12236-2","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=25735","title":{"rendered":"Presolar stardust in highly pristine CM chondrites Asuka 12169 and Asuka 12236<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Larry R. Nittler, Conel M. O\u2019D. Alexander, Andrea Patzer, Maximilien J. Verdier\u2010Paoletti<\/p>\n\n\n\n<p>Meteoritics &amp; Planetary Science<br>Version of Record online: 18 January 2021<\/p>\n\n\n\n<p><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/full\/10.1111\/maps.13618\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/epdf\/10.1111\/maps.13618\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;We report a NanoSIMS search for presolar grains in the CM chondrites Asuka (A) 12169 and A12236. We found 90 presolar O\u2010rich grains and 25 SiC grains in A12169, giving matrix\u2010normalized abundances of 275 (+55\/\u221250, 1\u03c3) ppm or, excluding an unusually large grain, 236 (+37\/\u221234) ppm for O\u2010rich grains and 62 (+15\/\u221212) ppm for SiC grains. For A12236, 18 presolar silicates and 6 SiCs indicate abundances of 58 (+18\/\u221212) and 20 (+12\/\u22128) ppm, respectively. The SiC abundances are in the typical range of primitive chondrites. The abundance of presolar O\u2010rich grains in A12169 is essentially identical to that in CO3.0 Dominion Range 08006, higher than in any other chondrites, while in A12236, it is higher than found in other CMs. These abundances provide further strong support that A12169 and A12236 are the least\u2010altered CMs as indicated by petrographic investigations. The similar abundances, isotopic distributions, silicate\/oxide ratios, and grain sizes of the presolar O\u2010rich grains found here to those of presolar grains in highly primitive CO, CR, and ungrouped carbonaceous chondrites (CCs) indicate that the CM parent body(ies) accreted a similar population of presolar oxides and silicates in their matrices to those accreted by the parent bodies of the other CC groups. The lower abundances and larger grain sizes seen in some other CMs are thus most likely a result of parent\u2010body alteration and not heterogeneity in nebular precursors. Presolar silicates are unlikely to be present in high abundances in returned samples from asteroids Ryugu and Bennu since remote\u2010sensing data indicate that they have experienced substantial aqueous alteration.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Larry R. Nittler, Conel M. O\u2019D. Alexander, Andrea Patzer, Maximilien J. Verdier\u2010Paoletti Meteoritics &amp; Planetary ScienceVersion of Record online: 18 January 2021 LINK (OPEN ACCESS)PDF (OPEN ACCESS) &#8220;We report a NanoSIMS search for presolar grains&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,18,76],"tags":[5421,5420,3273,105,3646,1853,539],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25735"}],"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=25735"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25735\/revisions"}],"predecessor-version":[{"id":25736,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25735\/revisions\/25736"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=25735"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=25735"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=25735"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}