...
首页> 外文期刊>The Astrophysical journal >STELLAR ORIGINS OF EXTREMELY 13C- AND 15N-ENRICHED PRESOLAR SIC GRAINS: NOVAE OR SUPERNOVAE?
【24h】

STELLAR ORIGINS OF EXTREMELY 13C- AND 15N-ENRICHED PRESOLAR SIC GRAINS: NOVAE OR SUPERNOVAE?

机译:富含13C和15N的前SIC颗粒的星状起源:是新星还是超新星?

获取原文
   

获取外文期刊封面封底 >>

       

摘要

Extreme excesses of 13C (12C/13C 10) and 15N (14N/15N 20) in rare presolar SiC grains have been considered diagnostic of an origin in classical novae, though an origin in core collapse supernovae (CCSNe) has also been proposed. We report C, N, and Si isotope data for 14 submicron- to micron-sized 13C- and 15N-enriched presolar SiC grains (12C/13C 16 and 14N/15N ~100) from Murchison, and their correlated Mg–Al, S, and Ca–Ti isotope data when available. These grains are enriched in 13C and 15N, but with quite diverse Si isotopic signatures. Four grains with 29,30Si excesses similar to those of type C SiC grains likely came from CCSNe, which experienced explosive H burning occurred during explosions. The independent coexistence of proton- and neutron-capture isotopic signatures in these grains strongly supports heterogeneous H ingestion into the He shell in pre-supernovae. Two of the seven putative nova grains with 30Si excesses and 29Si depletions show lower-than-solar 34S/32S ratios that cannot be explained by classical nova nucleosynthetic models. We discuss these signatures within the CCSN scenario. For the remaining five putative nova grains, both nova and supernova origins are viable because explosive H burning in the two stellar sites could result in quite similar proton-capture isotopic signatures. Three of the grains are sub-type AB grains that are also 13C enriched, but have a range of higher 14N/15N. We found that 15N-enriched AB grains (~50 14N/15N ~100) have distinctive isotopic signatures compared to putative nova grains, such as higher 14N/15N, lower 26Al/27Al, and lack of 30Si excess, indicating weaker proton-capture nucleosynthetic environments.
机译:尽管已经提出了核心塌陷超新星(CCSNe)的起源,但稀有的前太阳系SiC晶粒中极端过量的13C(12C / 13C <10)和15N(14N / 15N <20)被认为可以诊断经典新星。 。我们报告了来自默奇森的14个亚微米至微米尺寸的富含13C和15N的前太阳能SiC晶粒(12C / 13C <16和14N / 15N <〜100)的C,N和Si同位素数据,以及它们相关的Mg-Al ,S和Ca-Ti同位素数据(如果有)。这些晶粒富含13 C和15 N,但具有相当多样的Si同位素特征。四种C型SiC晶粒中的过量29,30Si晶粒可能来自CCSNe,它们在爆炸过程中经历了爆炸性H燃烧。这些颗粒中质子和中子俘获同位素特征的独立共存,有力地支持了超新星前氦壳中的异质H摄入。推测的30Si过量和29Si耗尽的新星晶粒中的两个显示出比太阳低的34S / 32S比,这无法用经典的新星核合成模型解释。我们在CCSN场景中讨论这些签名。对于其余的五个推定的新星颗粒,新星和超新星起源都是可行的,因为在两个恒星部位的爆炸性H燃烧会产生非常相似的质子捕获同位素特征。其中三个晶粒是亚型AB晶粒,也富集13C,但具有更高的14N / 15N范围。我们发现,与假定的新星相比,富含15N的AB晶粒(〜50 <14N / 15N <〜100)具有独特的同位素特征,例如较高的14N / 15N,较低的26Al / 27Al和缺少30Si的过量,表明质子较弱捕获核合成环境。

著录项

获取原文

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号