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arXiv 1301.7470astro-ph.EP
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Wild 2彗星颗粒和超碳星际尘埃颗粒中3.4微米特征的起源

The origin of the 3.4 micron feature in Wild 2 cometary particles and in ultracarbonaceous interplanetary dust particles

Graciela Matrajt, George Flynn, Don Brownlee, Dave Joswiak, Sasa Bajt

摘要:

用红外光谱法分析了2个超碳质行星际尘埃粒子和2个彗星Wild 2粒子。我们的特点是在这些样品中的载体的3.4微米带,并比较其配置文件和CH 2/CH 3比的3.4微米带中的扩散星际介质(DISM),在不溶性有机物(IOM)从3个原始陨石,在小行星24 Themis和彗星103 P/哈特利2的昏迷。我们发现Wild 2和IDP中的3.4微米波段是相似的,但与我们比较的所有其他天体物理环境不同。IDPs和Wild 2粒子中的3.4微米带主要由CH 2基团组成,峰比陨石,小行星Themis和DISM中的峰更窄,更强。此外,羰基C=O在1700 cm-1(5.8微米)在我们的样品的光谱中的大部分的存在下,表明这些脂肪链有O键合到他们,这是非常不同的天文光谱的DISM。根据这些观测结果,我们认为IDPs和Wild 2样品中3.4 μ m波段的载流子不是来自星际,而是来自太阳星云的最外层。

英文摘要:

We analyzed 2 ultra-carbonaceous interplanetary dust particles and 2 cometary Wild 2 particles with infrared spectroscopy. We characterized the carrier of the 3.4 micron band in these samples and compared its profile and the CH2/CH3 ratios to the 3.4 micron band in the diffuse interstellar medium (DISM), in the insoluble organic matter (IOM) from 3 primitive meteorites, in asteroid 24 Themis and in the coma of comet 103P/Hartley 2. We found that the 3.4 micron band in both Wild 2 and IDPs is similar, but different from all the other astrophysical environments that we compared to. The 3.4 micron band in IDPs and Wild 2 particles is dominated by CH2 groups, the peaks are narrower and stronger than in the meteorites, asteroid Themis, and the DISM. Also, the presence of the carbonyl group C=O at 1700 cm-1 (5.8 micron) in most of the spectra of our samples, indicates that these aliphatic chains have O bonded to them, which is quite different from astronomical spectra of the DISM. Based on all these observations we conclude that the origin of the carrier of the 3.4 micron band in IDPs and Wild 2 samples is not interstellar, instead, we suggest that the origin lies in the outermost parts of the solar nebula.

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