41Ca in Presolar Graphite of Supernova Origin
41Ca in Presolar Graphite of Supernova Origin
复制标题
超新星起源的太阳系前石墨中的 41Ca
DOI：
10.1086/310306
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
R. Lewis
中科院分区：
文献类型：
--
作者：
S. Amari;E. Zinner;R. Lewis
来自Murchison陨石的五个低密度石墨颗粒有大量的41K过量，这可以归因于41Ca的衰变。推断出的41Ca/40Ca比值高达1.7 × 10-2，以及其他同位素特征，15N、18O和28Si过量以及26Al/27Al高比值，表明这些颗粒起源于II型超新星，是超新星喷射物非均质混合的证据。41Ca似乎主要来源于富c和富o超新星带的中子捕获，只有少量的贡献来自o燃烧带。从富氧带到外层富c层的混合物质需要解释稳定的Ca同位素的丰度模式。相反，钛同位素组成反映了富c带的同位素组成，不需要大量来自富o带的物质。
Five low-density graphite grains from the Murchison meteorite have large 41K excesses that can be attributed to the decay of 41Ca. The inferred 41Ca/40Ca ratios, which range up to 1.7 × 10-2, and other isotopic signatures,15N,18O, and 28Si excesses and high 26Al/27Al ratios, indicate a Type II supernova origin for these grains and are evidence for heterogeneous mixing of supernova ejecta.41Ca seems to mainly originate from neutron capture in the C-rich and O-rich supernova zones, with only minor contributions from the O-burning zone. Admixture of material from the O-rich zone to outer C-rich layers is required to explain the abundance patterns of the stable Ca isotopes. In contrast, the Ti isotopic compositions reflect that of the C-rich zone and do not require substantial amounts of material from the O-rich zone.