利用Ia型超新星光谱中钠吸收特征研究其前身星环境

发布时间：2018-04-01 12:04

本文选题：钠双线　切入点：Ia型超新星　出处：《清华大学》2013年硕士论文

【摘要】：由于Ia超新星具有光亮度且相对均匀，它们被长期用作研究宇宙的“标准烛光”测量河外距离，，并在揭示宇宙加速膨胀这一重大发现上起了至关重要的作用。然而其爆发前身星性质的不确定性却不利于使用Ia超新星进行更加精确的宇宙学研究。现在人们普遍相信Ia超新星起源于碳氧白矮星的热核爆炸。然而，对于具体是两个C+O白矮星的并合引发的爆炸（所谓的“双简并”图景），还是双星系统中中心白矮星对其富H/He的伴星物质的持续吸积引发的（“单简并”模型），却无定论。在单简并模型中，从星体被吹出的物质会聚集形成可探测的星周物质；而在双简并模型中此种现象则不明显。因此探测星周物质/尘埃是区分两类模型的关键。静止波长在5890和5896的钠双线（Na I D）是很好的尘埃气体指示器。在这篇文章中，我们测量了来自哈佛大学天体物理中心的2603条Ia超新星光谱中Na I D线吸收强度及其随时间的演化。发现了如下三个事实：1）部分超新星主星系钠强度呈现形状类似“根号”的演化规律，这与我们建立的星周物质被超新星辐射电离的模型非常吻合；2）这些具有变化钠特征的超新星倾向于具有很高的抛射物速度（“高速”超新星）；3）高速超新星比正常抛射物速度的超新星（“正常速度”超新星）系统性地颜色偏红且Na吸收更强。以上事实证明了部分Ia超新星周围致密星周尘埃的存在，且对“高速”（HV）和“正常速度”（NV）超新星可能具有的两种不同前身星演化模型给予极强的暗示。大量星周尘埃更容易聚集在“高速”超新星周围使我们相信，这类Ia超新星倾向于起源于“单简并”系统的爆炸。而其比“正常速度”超新星系统偏红也与除星际尘埃影响外，“高速”超新星还遭遇额外的星周尘埃消光这一事实不谋而合。
[Abstract]:Because Ia supernovae are luminous and relatively uniform, they have long been used for "standard candlelight" measurements of extragalactic distances in the study of the universe. It plays an important role in revealing the great discovery of the accelerating expansion of the universe. However, the uncertainty of the character of its predecessor star is not conducive to a more accurate cosmological study using Ia supernova. It is now widely believed that the Ia supernova originated from a thermonuclear explosion of carbon dioxide white dwarfs. For the explosion caused by the combination of the two C-O white dwarfs (the so-called "double degenerate" picture, or the continuous accretion of the central white dwarf to its H/He rich companion star material in the binary system, the "single degenerate" model, however, Indeterminate. In a single degenerate model, The matter blown out from the stars gathers to form detectable circumstellar matter, but this phenomenon is not obvious in the double degenerate model. Therefore, detecting the circumstellar matter / dust is the key to distinguish the two models. Sodium I D at rest wavelengths of 5890 and 5896 is a good indicator of dust and gas. In this article, We have measured the absorption intensity of Na D lines and their evolution over time in 2603 Ia supernova spectra from the Harvard Astrophysical Center. The law of evolution like "root sign", This is very consistent with our model of supernova radiation ionization of perisatellite matter. (2) these supernovae with varying sodium characteristics tend to have very high projectile velocity ("high speed" supernova) supernova than normal supernova. Projective velocity supernovae ("normal velocity" supernovae) are systematically reddish and Na absorbers are stronger. The above facts prove the existence of the dense circumstellar dust around some Ia supernovae. And gives a very strong indication of two different models of evolution of precursors that supernova "high speed" (HVV) and "normal speed" (NVN) may have. Large amounts of circumstellar dust tend to gather around "high speed" supernovae to convince us. This type of Ia supernova tends to originate from an explosion in a "single degenerate" system, and its redder than "normal velocity" supernova system coincides with the fact that, in addition to interstellar dust, the "high-speed" supernova suffers from additional circumstellar dust extinction.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P145.3

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