Chemical enrichment and star formation in the Milky Way disk - III. Chemodynamical constraints
Chemical enrichment and star formation in the Milky Way disk - III. Chemodynamical constraints
复制标题
银河系盘中的化学富集和恒星形成 - III。
DOI：
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发表时间：
2004
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通讯作者：
G. Hensler
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文献类型：
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作者：
H. Rocha;H. Rocha;C. Flynn;J. Scalo;J. Hanninen;W. J. Maciel;G. Hensler
在本文中，我们利用由 424 个晚期矮星组成的样本研究了银河系盘的一些化学运动学特性。我们证明，根据与 t 0.26 成正比的定律，恒星群的速度色散与该恒星群的年龄相关，其中 t 是恒星群的年龄。详细考虑了顶点偏差的时间演化。结果表明，顶点偏差似乎并不强烈依赖于恒星群的年龄。之前的文献研究似乎没有发现这一点，因为使用的是恒星群体的统计年龄，而不是个体年龄。研究了使用恒星的轨道参数来获取有关其诞生地的信息的可能性，并且我们表明平均银河中心半径可能是最可靠的恒星诞生地指标。然而，由于从附近恒星构建的所有样本中都存在内在偏差，该信息目前不能用于推导径向演化约束。对常用于解释年龄-速度色散关系的长期和随机加热机制进行了广泛的讨论。我们认为年龄-速度色散关系可以反映盘状恒星形成的湍流速度色散的逐渐减少，这一建议最初由 Tinsley & Larson (1978, ApJ, 221, 554) 提出，并得到了一些最近的盘演化计算的支持。提出了一种使用高红移星系来区分两种类型模型的测试。
In this paper, we investigate some chemokinematical properties of the Milky Way disk, by using a sample composed by 424 late-type dwarfs. We show that the velocity dispersion of a stellar group correlates with the age of this group, according to a law proportional to t 0.26 ,w heret is the age of the stellar group. The temporal evolution of the vertex deviation is considered in detail. It is shown that the vertex deviation does not seem to depend strongly on the age of the stellar group. Previous studies in the literature seem to not have found it due to the use of statistical ages for stellar groups, rather than individual ages. The possibility to use the orbital parameters of a star to derive information about its birthplace is investigated, and we show that the mean galactocentric radius is likely to be the most reliable stellar birthplace indicator. However, this information cannot be presently used to derive radial evolutionary constraints, due to an intrinsic bias present in all samples constructed from nearby stars. An extensive discussion of the secular and stochastic heating mechanisms commonly invoked to explain the age-velocity dispersion relation is presented. We suggest that the age-velocity dispersion relation could reflect the gradual decrease in the turbulent velocity dispersion from which disk stars form, a suggestion originally made by Tinsley & Larson (1978, ApJ, 221, 554) and supported by several more recent disk evolution calculations. A test to distinguish between the two types of models using high-redshift galaxies is proposed.