J/ApJ/831/197ivo://CDS.VizieR/J/ApJ/831/197doi:10.26093/cds/vizier.18310197CDSRudraswami N.G.Shyam Prasad M.Dey S.Fernandes D.Plane J.M.C.,Feng W.Taylor S.Carrillo-Sanchez J.D.2017-04-24T07:47:10Z2017-03-14T07:18:39ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frasteroidsAntarctica micrometeorites (~1200) and cosmic spherules (~5000) from deep sea sediments are studied using electron microscopy to identify Mg-rich olivine grains in order to determine the nature of the particle precursors. Mg-rich olivine (FeO<5wt%) in micrometeorites suffers insignificant chemical modification during its history and is a well-preserved phase. We examine 420 forsterite grains enclosed in 162 micrometeorites of different types-unmelted, scoriaceous, and porphyritic-in this study. Forsterites in micrometeorites of different types are crystallized during their formation in solar nebula; their closest analogues are chondrule components of CV-type chondrites or volatile rich CM chondrites. The forsteritic olivines are suggested to have originated from a cluster of closely related carbonaceous asteroids that have Mg-rich olivines in the narrow range of CaO (0.1-0.3wt%), Al_2_O_3_ (0.0-0.3wt%), MnO (0.0-0.3wt%), and Cr_2_O_3_ (0.1-0.7wt%). Numerical simulations carried out with the Chemical Ablation Model (CABMOD; Vondrak+ 2008ACP.....8.7015V) enable us to define the physical conditions of atmospheric entry that preserve the original compositions of the Mg-rich olivines in these particles. The chemical compositions of relict olivines affirm the role of heating at peak temperatures and the cooling rates of the micrometeorites. This modeling approach provides a foundation for understanding the ablation of the particles and the circumstances in which the relict grains tend to survive.2016ApJ...831..197Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/831/197CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/MNRAS/406/460 : IR absorbance spectra of olivine (Pitman+, 2010)J/A+A/449/583 : Temperature effects on spectra ofhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/831/197https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/831/197http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/831/197https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/831/197https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/831/197http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/831/197GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/ApJ/831/197/table1Relict olivine grain in Antartica micrometeorites and Deep sea cosmic spherulesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTypeMicrometeorite type (AMM = Antarctica micrometeorite (182 instances) or DSS = deep sea sediments (238 instances))src.classcharIDMicrometeorite identifiermeta.id;meta.maincharDiam[41/426] Micrometeorite diameter (1)umphys.size.diameterintLen[5/227] Length of relict grainumsrc.morph.scLengthintBre[4/170] Breadth of relict grainumsrc.morph.scLengthintPoint[1/40] Point / 1%stat.fit.paramintNa2O[0/0.6] Percent Na_2_O in micrometeorite composition%phys.abundfloatMgO[45/60] Percent MgO in micrometeorite composition%phys.abundfloatAl2O3[0/1.2] Percent Al_2_O_3_ in micrometeorite composition%phys.abundfloatSiO2[33.7/46] Percent SiO_2_ in micrometeorite composition%phys.abundfloatP2O5[0/0.3] Percent P_2_O_5_ in micrometeorite composition%phys.abundfloatSO2[0/0.5] Percent SO_2_ in micrometeorite composition%phys.abundfloatK2O[0/0.05] Percent K_2_O in micrometeorite composition%phys.abundfloatCaO[0.02/3.1] Percent CaO in micrometeorite composition%phys.abundfloatTiO2[0/0.3] Percent TiO_2_ in micrometeorite composition%phys.abundfloatCr2O3[0.04/0.8] Percent Cr_2_O_3_ in micrometeorite composition%phys.abundfloatMnO[0/0.9] Percent MnO in micrometeorite composition%phys.abundfloatFeO[0.4/5.1] Percent FeO in micrometeorite composition%phys.abundfloatCoO[0/0.2] Percent CoO in micrometeorite composition%phys.abundfloatNiO[0/0.6] Percent NiO in micrometeorite composition%phys.abundfloatTotal[97/102] Previous columns in total composition%phys.abundfloatMg2SiO4[94.8/99.6] Percent Mg_2_SiO_4_ in micrometeorite composition%phys.abundfloatFe2Si4[0.4/5.2] Percent Fe_2_Si_4_ in micrometeorite composition%phys.abundfloat