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arXiv 0901.2066astro-ph.GA
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Milky Way中的气体动力学:核棒和3-kpc臂

Gas dynamics in the Milky Way: the nuclear bar and the 3-kpc arms

N. J. Rodriguez-Fernandez

摘要:

我们讨论了在银河系中存在两个酒吧的气体动力学的第一个模型的结果:大规模的主酒吧或boxy隆起和次级酒吧在银河系中心区域。我们已经得到了一个准确的潜力,通过模拟2 MASS星计数,我们已经使用这个潜力来模拟气体动力学。作为一级近似,我们采用了一个单一的模式速度Ω_p。Ω_p=30-40 \kmskpc和主棒取向为20-35 °的模型成功地再现了观测到的速度-速度图的许多特征,如终极速度曲线或旋臂切点。银河系分子环并不是一个真正的环,而是旋臂的内部,在共转中。该模型定量地再现了“3千秒差距臂”和最近发现的远侧对应物,这是横向臂,轮廓酒吧。在银河系中心区域,该模型再现了1 kpc的HI环和中央分子区(CMZ),这是气体对次级棒的响应。为了再现观测到的CMZ CO经度速度图的“X”形,次级棒应相对于太阳-GC线定向60-70度。次级棒的质量为(2-5.5)10^9 Msun,是初级棒质量的10- 25%。

英文摘要:

We discuss the results of the first model of the gas dynamics in the Milky Way in the presence of two bars: the large scale primary bar or boxy bulge and a secondary bar in the Galactic center region. We have obtained an accurate potential by modeling 2MASS star counts and we have used this potential to simulate the gas dynamics. As a first approximation we have used one single pattern speed Ω_p. The models with Omega_p=30-40 \kmskpc and a primary bar orientation of 20-35 deg reproduce successfully many characteristics of the observed longitude-velocity diagrams as the terminal velocity curve or the spiral arm tangent points. The Galactic Molecular Ring is not an actual ring but the inner part of the spiral arms, within corotation. The model reproduces quantitatively the "3-kpc arm" and the recently found far-side counterpart, which are the lateral arms that contour the bar. In the Galactic center region, the model reproduces the 1-kpc HI ring and the Central Molecular Zone (CMZ), which is the gas response to the secondary bar. In order to reproduce the observed parallelogram shape of the CO longitude velocity diagram of the CMZ, the secondary bar should be oriented by and angle of 60-70 deg with respect to the Sun-GC line. The mass of the secondary bar amounts to (2-5.5)10^9 Msun, which is 10-25 % of the mass of the primary bar.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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