arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2007.01297astro-ph.SRastro-ph.EPastro-ph.GA
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太阳丰度问题与星团中的eMSTOs

The solar abundance problem and eMSTOs in clusters

R. Hoppe, M. Bergemann, B. Bitsch, A. Serenelli

摘要:

研究了原行星盘吸积对AFG型恒星恒星演化的影响。我们使用一个简化的光盘模型计算使用两个流行的Py代码,包含的尘埃颗粒的生长和漂移的原行星盘。它被用来模拟原行星盘的一系列物理条件下的吸积情景。两个极限情况下结合使用的Garstec恒星演化代码计算恒星对流信封的演变。我们发现贫金属(气体)或富金属(尘埃)物质的吸积对恒星对流包层的化学成分有显着的影响。因此,恒星的演化轨迹偏离了经典恒星演化模型预测的标准场景,这些模型假设恒星组装完成后化学成分恒定且均匀。在太阳的情况下,我们发现对太阳化学成分的影响不大。贫金属物质的吸积确实降低了太阳大气的整体金属丰度,并且在不确定性范围内与Caffau等人(2011)报告的太阳Z一致,但我们的模型与Asplund等人(2009)的测量不一致。另一个影响是恒星在色星等图中的位置变化。我们比较我们的预测一组疏散星团从盖亚DR 2和表明,它是可能的,以产生一个分散接近关闭的年轻的集群,可以有助于解释所观察到的分散在CMD。对附近疏散星团金属丰度和丰度的详细测量将为我们提出的设想提供一个严格的观测测试。

英文摘要:

We study the impact of accretion from protoplanetary discs on stellar evolution of AFG-type stars. We use a simplified disc model computed using the Two-Pop-Py code that contains the growth and drift of dust particles in the protoplanetary disc. It is used to model the accretion scenarios for a range of physical conditions of protoplanetary discs. Two limiting cases are combined with the evolution of stellar convective envelopes computed using the Garstec stellar evolution code. We find that the accretion of metal-poor (gas) or metal-rich (dust) material has a significant impact on the chemical composition of the stellar convective envelope. As a consequence, the evolutionary track of the star diverts from the standard scenario predicted by canonical stellar evolution models, which assume a constant and homogeneous chemical composition after the assembly of the star has finished. In the case of the Sun, we find a modest impact on the solar chemical composition. Accretion of metal-poor material indeed reduces the overall metallicity of the solar atmosphere, and it is consistent, within the uncertainty, with the solar Z reported by Caffau et al. (2011), but our model is not consistent with the measurement by Asplund et al. (2009). Another effect is the change of the position of the star in the colour-magnitude diagram. We compare our predictions to a set of open clusters from the Gaia DR2 and show that it is possible to produce a scatter close to the turn-off of young clusters that could contribute to explain the observed scatter in CMDs. Detailed measurements of metallicities and abundances in the nearby open clusters will provide a stringent observational test of our proposed scenario.

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