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arXiv 1107.4541astro-ph.GAastro-ph.COastro-ph.SR
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银河系尘埃的形成与演化。I.冷凝效应

Formation and Evolution of the Dust in Galaxies. I. The Condensation Efficiencies

L. Piovan, C. Chiosi, E. Merlin, T. Grassi, R. Tantalo, U. Buonomo, L. P. Cassarà

摘要:

对高z宇宙的兴趣日益增长,其中存在强烈遮蔽的物体,已经决定努力改善星系中尘埃形成和演化的模拟。三个主要的基本成分进入的问题,影响总的尘埃预算和尘埃颗粒的混合物:类型和数量的尘埃注入AGB星和SNae和吸积/销毁过程中的ISM尘埃。它们控制着ISM中气体和尘埃的相对丰度。在这项研究中,我们专注于星尘,并提出了一个数据库的冷凝效率的难熔元素C,O,Mg,Si,S,Ca和Fe的AGB星和SNae,可以很容易地应用于气态喷出物,以确定的数量和种类的难熔元素本地嵌入尘埃和注入ISM。最好的理论配方,目前在文献中估计的尘埃产生的SNAE和AGB星的数量进行了讨论,并为SNAE相比,观察到的问题,以获得线索。凝聚效率已被分析的背景下,在太阳附近和银河系盘的尘埃形成和演化的经典化学模型。表的系数(i)AGB星在不同的金属丰度和(ii)SNae在不同的密度n_H的ISM的SNa爆炸发生。特别是,我们展示了如何有争议的CNT近似广泛采用形成尘埃在SNAE,仍然给出了很好的结果,并同意来自观测的一些线索。然而,需要新一代的尘埃形成模型在SNAE解决最近出现的一些矛盾。一个简单的数据库的冷凝效率被设置为用于化学模型,包括灰尘的影响,并意味着模拟星系从原始的原星系到目前在本地宇宙中看到的。

英文摘要:

The growing interest in the high-z universe, where strongly obscured objects are present, has determined an effort to improve the simulations of dust formation and evolution in galaxies. Three main basic ingredients enter the problem influencing the total dust budget and the mixture of the dust grains: the types and amounts of dust injected by AGB stars and SNae and the accretion/destruction processes of dust in the ISM. They govern the relative abundances of the gas and dust in the ISM. In this study, we focus on star-dust and present a database of condensation efficiencies for the refractory elements C, O, Mg, Si, S, Ca and Fe in AGB stars and SNae that can be easily applied to the gaseous ejecta, in order to determine the amount and kind of refractory elements locally embedded into dust and injected into the ISM. The best theoretical recipes available nowadays in literature to estimate the amount of dust produced by SNae and AGB stars have been discussed and for SNae compared to the observations to get clues on the problem. The condensation efficiencies have been analyzed in the context of a classical chemical model of dust formation and evolution in the Solar Neighbourhood and Galactic Disk. Tables of coefficients are presented for (i) AGB stars at varying the metallicity and (ii) SNae at varying the density n_H of the ISM where the SNa explosions took place. In particular, we show how the controversial CNT approximation widely adopted to form dust in SNae, still gives good results and agrees with some clues coming from the observations. A new generation of dust formation models in SNae is however required to solve some contradictions recently emerged. A simple database of condensation efficiencies is set up to be used in chemical models including the effect of dust and meant to simulate galaxies going from primordial proto-galaxies to those currently seen in the local universe.

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