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arXiv 2106.07076astro-ph.GA
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用Gaia DR2动力学模拟太阳邻域的非平衡

Non-equilibrium in the Solar Neighbourhood using dynamical modelling with Gaia DR2

Rain Kipper, Peeter Tenjes, Elmo Tempel, Roberto de Propris

摘要:

银河系的物质分布模型通常是静止的,尽管在总密度的$\sim10\%$水平上已知盘中存在波动扰动。通过允许非平衡来模拟整个加速度场是一项复杂的任务。我们必须学会根据密度增强的性质来区分它们是否是持久的。在本文中,我们阐述了我们的轨道弧方法,包括无质量扰动和非平稳性的影响建模。通过对仿真数据的建模,验证了该方法的有效性。我们应用该方法的盖亚DR 2数据的$\sim 0.5$ kpc的区域内,从太阳和确认,在太阳邻域的加速度场具有扰动的性质-沿恒星轨道的相空间密度增长的顺序$h\lesssim 5\%$每百万年由于非平稳性。这个结果是一个时间上的局部值,只能在几个百万年的时间范围内使用。对扰动源的定位表明,具有较大绝对角动量的恒星是局部扰动的主要载体。由于它们的速度比一般的薄盘星快,它们要么起源于更远的地方,靠近近心点,要么受到快速共同运动的扰动的局部扰动,例如气体盘不均匀性。

英文摘要:

Matter distribution models of the Milky Way galaxy are usually stationary, although there are known to be wave-like perturbations in the disc at $\sim10\%$ level of the total density. Modelling of the overall acceleration field by allowing non-equilibrium is a complicated task. We must learn to distinguish whether density enhancements are persistent or not by their nature. In the present paper, we elaborate our orbital arc method to include the effects of massless perturbations and non-stationarities in the modelling. The method is tested by modelling of simulation data and shown to be valid. We apply the method to the Gaia DR 2 data within a region of $\sim 0.5$ kpc from the Sun and confirm that acceleration field in the Solar Neighbourhood has a perturbed nature -- the phase space density along the orbits of stars grow in the order of $h\lesssim 5\%$ per Myr due to non-stationarity. This result is a temporally local value and can be used only within the timeframe of a few Myrs. An attempt to pinpoint the origin of the perturbation shows that the stars having larger absolute angular momentum are the main carriers of the local perturbation. As they are faster than the average thin disc star, they are either originating further away and are close in their pericentre or they are perturbed locally by a fast co-moving perturber, such as gas disc inhomogenities.

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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