Brown L E, Clayton D D
Science. 1992 Nov 6;258(5084):970-2. doi: 10.1126/science.258.5084.970.
Large silicon carbide (SiC) particles extracted from acid-insoluble residues of carbonaceous chondrites are isotopically anomalous in both silicon and carbon and contain isotopically extreme noble gases. These particles are thought to have originated in mass outflows from red giant stars and to have existed in the interstellar medium at the time the solar system formed from an interstellar cloud. Calculations show that the silicon isotope correlations in those large SiC particles can be generated only in the most massive carbon stars. Consequently, the almost pure neon-22 ((22)Ne) in those particles must be interpreted as the condensation of radioactive sodium-22 ((22)Na) in the particles as they flowed away from the stars. The (22)Na is produced through proton capture by (21)Ne at the base of the surface convection zone. Neon-22 does not exist abundantly in helium shells hot enough to burn magnesium, which is necessary to establish the measured silicon isotopic composition.
从碳质球粒陨石的酸不溶残渣中提取的大颗粒碳化硅（SiC）在硅和碳方面都存在同位素异常，并且含有同位素极端的惰性气体。这些颗粒被认为起源于红巨星的质量外流，并且在太阳系由星际云形成时就已存在于星际介质中。计算表明，那些大的SiC颗粒中的硅同位素相关性只能在质量最大的碳星中产生。因此，那些颗粒中几乎纯的氖 - 22（²²Ne）必须被解释为当颗粒从恒星流出时，放射性钠 - 22（²²Na）在颗粒中的凝聚。²²Na是通过表面对流区底部的²¹Ne质子俘获产生的。在足够热以燃烧镁的氦壳层中，氖 - 22并不大量存在，而燃烧镁对于确定所测量的硅同位素组成是必要的。
