{"title":"仙后座亚科的进化状况及内部结构","authors":"K. Bach","doi":"10.5303/JKAS.2015.48.3.165","DOIUrl":null,"url":null,"abstract":"We investigate physical properties of the nearby (∼ 7.5 pc) astrometric binary μ Cas in the context of standard evolutionary theory. Based on the spectroscopically determined relative abundances ([α/Fe] ? +0.4 dex, [Fe/H] ∼ ?0.7 dex), all physical inputs such as opacities and equation of state are consistently generated. By combining recent spectroscopic analyses with the astrometric observations from the HIPPARCOS parallaxes and the CHARA array, the evolutionary model grids have been constructed. Through the statistical evaluation of the χ²-minimization among alternative models, we find a reliable evolutionary solution (M A , M B , t age ) = (0.74 M ⊙ , 0.19 M ⊙ , 11 Gyr) which excellently satisfies observational constraints. In particular, we find that the helium abundance of μ Cas is comparable with the primordial helium contents (Y p ∼ 0.245). On the basis of the well-defined stellar parameters of the primary star, the internal structure and the p-mode frequencies have been estimated. From our seismic computation, μ Cas is expected to have a first order spacing ?ν ∼ 169 μHz. The ultimate goal of this study is to describe physical processes inside a low-mass star through a complete modelling from the spectroscopic observation to the evolutionary computation.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":null,"pages":null},"PeriodicalIF":1.1000,"publicationDate":"2015-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":"{\"title\":\"EVOLUTIONARY STATUS AND INTERNAL STRUCTURE OF μ CASSIOPEIAE\",\"authors\":\"K. Bach\",\"doi\":\"10.5303/JKAS.2015.48.3.165\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"We investigate physical properties of the nearby (∼ 7.5 pc) astrometric binary μ Cas in the context of standard evolutionary theory. Based on the spectroscopically determined relative abundances ([α/Fe] ? +0.4 dex, [Fe/H] ∼ ?0.7 dex), all physical inputs such as opacities and equation of state are consistently generated. By combining recent spectroscopic analyses with the astrometric observations from the HIPPARCOS parallaxes and the CHARA array, the evolutionary model grids have been constructed. Through the statistical evaluation of the χ²-minimization among alternative models, we find a reliable evolutionary solution (M A , M B , t age ) = (0.74 M ⊙ , 0.19 M ⊙ , 11 Gyr) which excellently satisfies observational constraints. In particular, we find that the helium abundance of μ Cas is comparable with the primordial helium contents (Y p ∼ 0.245). On the basis of the well-defined stellar parameters of the primary star, the internal structure and the p-mode frequencies have been estimated. From our seismic computation, μ Cas is expected to have a first order spacing ?ν ∼ 169 μHz. The ultimate goal of this study is to describe physical processes inside a low-mass star through a complete modelling from the spectroscopic observation to the evolutionary computation.\",\"PeriodicalId\":49994,\"journal\":{\"name\":\"Journal of the Korean Astronomical Society\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.1000,\"publicationDate\":\"2015-06-30\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"1\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of the Korean Astronomical Society\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://doi.org/10.5303/JKAS.2015.48.3.165\",\"RegionNum\":4,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the Korean Astronomical Society","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.5303/JKAS.2015.48.3.165","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 1
摘要
我们在标准进化理论的背景下研究了附近(~ 7.5 pc)天体测量双星μ Cas的物理性质。根据光谱测定的相对丰度([α/Fe] ?+0.4指数,[Fe/H] ~ - 0.7指数),所有的物理输入,如不透明度和状态方程一致地产生。通过结合最近的光谱分析和HIPPARCOS视差和CHARA阵列的天文观测,构建了演化模型网格。通过对备选模型之间的χ 2最小化的统计评价,我们找到了一个可靠的进化解(M a, M B, t age) = (0.74 M⊙,0.19 M⊙,11 Gyr),它很好地满足观测约束。特别是,我们发现μ Cas的氦丰度与原始氦含量相当(Y p ~ 0.245)。在确定主星参数的基础上,对其内部结构和p模频率进行了估计。从我们的地震计算中,μ Cas预计具有一阶间距?ν ~ 169 μ hz。本研究的最终目标是通过从光谱观测到演化计算的完整建模来描述低质量恒星内部的物理过程。
EVOLUTIONARY STATUS AND INTERNAL STRUCTURE OF μ CASSIOPEIAE
We investigate physical properties of the nearby (∼ 7.5 pc) astrometric binary μ Cas in the context of standard evolutionary theory. Based on the spectroscopically determined relative abundances ([α/Fe] ? +0.4 dex, [Fe/H] ∼ ?0.7 dex), all physical inputs such as opacities and equation of state are consistently generated. By combining recent spectroscopic analyses with the astrometric observations from the HIPPARCOS parallaxes and the CHARA array, the evolutionary model grids have been constructed. Through the statistical evaluation of the χ²-minimization among alternative models, we find a reliable evolutionary solution (M A , M B , t age ) = (0.74 M ⊙ , 0.19 M ⊙ , 11 Gyr) which excellently satisfies observational constraints. In particular, we find that the helium abundance of μ Cas is comparable with the primordial helium contents (Y p ∼ 0.245). On the basis of the well-defined stellar parameters of the primary star, the internal structure and the p-mode frequencies have been estimated. From our seismic computation, μ Cas is expected to have a first order spacing ?ν ∼ 169 μHz. The ultimate goal of this study is to describe physical processes inside a low-mass star through a complete modelling from the spectroscopic observation to the evolutionary computation.
期刊介绍:
JKAS is an international scientific journal publishing papers in all fields of astronomy and astrophysics. All manuscripts are subject to the scrutiny of referees. Manuscripts submitted to JKAS must comply with the ethics policy of JKAS. Six regular issues are published each year on February 28, April 30, June 30, August 31, October 31, and December 31. One year''s issues compose one volume.