{"id":30025,"date":"2022-01-31T19:15:52","date_gmt":"2022-01-31T18:15:52","guid":{"rendered":"https:\/\/karmaka.de\/?p=30025"},"modified":"2022-01-31T19:15:54","modified_gmt":"2022-01-31T18:15:54","slug":"microstructural-and-chemical-investigations-of-presolar-silicates-from-diverse-stellar-environments","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=30025","title":{"rendered":"Microstructural and Chemical Investigations of Presolar Silicates from Diverse Stellar Environments<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Manish N. Sanghani, Luc Lajaunie, Kuljeet Kaur Marhas, William D. A. Rickard, Silver Sung-Yun Hsiao, Zan Peeters, Hsien Shang, Der-Chuen Lee, Jos\u00e9. J. Calvino, and Martin Bizzarro<\/p>\n\n\n\n<p>The Astrophysical Journal, Volume 925, Number 2<\/p>\n\n\n\n<p><a href=\"https:\/\/iopscience.iop.org\/article\/10.3847\/1538-4357\/ac3332\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br><a href=\"https:\/\/iopscience.iop.org\/article\/10.3847\/1538-4357\/ac3332\/pdf\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;We report the structural and chemical investigation of nine presolar silicate grains from the CH3\/CBb3 chondrite Isheyevo and CR2 chondrite Northwest Africa (NWA) 801. Five of these grains belong to group 1, likely condensed in low- to intermediate-mass asymptotic giant branch (AGB) stars, super-AGB stars, or core-collapse supernovae, while the remaining four grains belong to group 4 and have a supernova origin. The advanced transmission electron microscopy and associated electron spectroscopy analyses show a diverse range of chemical and structural compositions for presolar silicates. Two GEMS (glass with embedded metal and sulfide)-like silicates, each from different groups, condensed under nonequilibrium conditions in stellar outflows. Two nonstoichiometric silicates from group 1 have dissimilar formation and alteration histories. An amorphous silicate from group 1 with olivine-like [(Mg,Fe)2SiO4] composition likely formed as a crystalline olivine that subsequently amorphized in the interstellar medium. An oldhamite (CaS) grain within a stoichiometric enstatite (MgSiO3) from group 1 probably formed by heterogeneous condensation in circumstellar outflows. Of the two crystalline grains from group 4, one is an antigorite [(Mg,Fe)3Si2O5(OH)4], while the other is a nontronite [Na,Fe2(Si,Al)4O10(OH)2.nH2O], both formed as a crystalline forsterite and later altered to have hydrated silicate composition. A group-4 silicate has a chemical composition similar to a low Ca-pyroxene [(Ca,Mg)(Si,Al)2O6]. Our data imply that presolar grains from different groups can have a similar range of grain-formation conditions.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Manish N. Sanghani, Luc Lajaunie, Kuljeet Kaur Marhas, William D. A. Rickard, Silver Sung-Yun Hsiao, Zan Peeters, Hsien Shang, Der-Chuen Lee, Jos\u00e9. J. Calvino, and Martin Bizzarro The Astrophysical Journal, Volume 925, Number 2 LINK&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,584,583,12,76],"tags":[1810,233,1853,538],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/30025"}],"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=30025"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/30025\/revisions"}],"predecessor-version":[{"id":30026,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/30025\/revisions\/30026"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=30025"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=30025"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=30025"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}