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arXiv 1801.09568astro-ph.SR
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CO经典新星的前太阳星尘颗粒

On Presolar Stardust Grains from CO Classical Novae

Christian Iliadis, Lori Downen, Jordi Jose, Larry Nittler, Sumner Starrfield

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摘要：

大约30%到40%的经典新星在爆发后20-100天产生尘埃，但还没有经典新星的前太阳星尘颗粒被明确确定。虽然有几项研究声称某些颗粒是新星的父亲，但测量和模拟的同位素比率只能假设这些颗粒是在新星喷出物与大量接近太阳的物质混合后凝结的。然而，这种潜在的爆炸后喷出物稀释的来源和机制仍然是一个谜。以前的研究的一个主要问题是少量的模拟和隐含的大新星参数空间探索差。我们报告的结果不同的策略，基于蒙特卡洛技术，涉及随机抽样的最重要的新星模型参数：白矮星组成;混合的外部白矮星层与吸积材料爆炸前;峰值温度和密度;爆炸的时间尺度;和可能的稀释后的喷出物爆发。我们讨论并考虑到系统的不确定性的前太阳颗粒测量和模拟结果。只有那些与给定颗粒的所有测量同位素比率一致的模拟才能被接受用于进一步分析。给出了模型参数的数值计算结果。我们确定了18个前太阳粒与测量的同位素签名一致的CO新星起源，而不假设任何稀释的喷出物。其中，G270 2、M11-334-2、G278、M11-347-4、M11-151-4和Ag 2 6具有最高的CO nova父系可能性。

英文摘要：

About 30% to 40% of classical novae produce dust 20-100 days after the outburst, but no presolar stardust grains from classical novae have been unambiguously identified yet. Although several studies claimed a nova paternity for certain grains, the measured and simulated isotopic ratios could only be reconciled assuming that the grains condensed after the nova ejecta mixed with a much larger amount of close-to-solar matter. However, the source and mechanism of this potential post-explosion dilution of the ejecta remains a mystery. A major problem with previous studies is the small number of simulations performed and the implied poor exploration of the large nova parameter space. We report the results of a different strategy, based on a Monte Carlo technique, that involves the random sampling over the most important nova model parameters: the white dwarf composition; the mixing of the outer white dwarf layers with the accreted material before the explosion; the peak temperature and density; the explosion time scales; and the possible dilution of the ejecta after the outburst. We discuss and take into account the systematic uncertainties for both the presolar grain measurements and the simulation results. Only those simulations that are consistent with all measured isotopic ratios of a given grain are accepted for further analysis. We also present the numerical results of the model parameters. We identify 18 presolar grains with measured isotopic signatures consistent with a CO nova origin, without assuming any dilution of the ejecta. Among these, the grains G270 2, M11-334-2, G278, M11-347-4, M11-151-4, and Ag2 6 have the highest probability of a CO nova paternity.

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