QQ客服 官方微博 反馈留言

题名	恒星自转速度的测定
作者	潘开科
学位类别	硕士
答辩日期	1990-06-30
授予单位	中国科学院云南天文台
授予地点	昆明
导师	谭徽松
中文摘要	不少人认为，现在仍被广泛用作恒星自转速度定标基准的Slettedak老系统的结果不够准确，本文以改善、甚至建立一个新的恒星自转速度定标系统为目的，对我们所能收集到的所有自转速度测定方法作了综合分析。介绍了各自的测量原理以及实测效果。分析了它们的适用范围，优、缺点等主要特性、重点讨论了现在的定标系统：Slettebak老系统，则量精度较高但计算过于昂贵的Slettebak新系统以及一种新的自转速度测定方法：卷积法。通过统计研究，我们对Slettebak新、老系统之间的差别作出了定量的估算：对VeSini ≤ 50KM/Sec.的星，两系统的结果基本一致，而对VeSini≥150KM/Sec的A、B、F星，老系统的值平均比新系统的结果大15%。更进一步地，我们从理论上分析了这种不一致的原因，并且得出结论：Slettebak老系统可能存在两个妥当之处：（1）临边昏暗系数取得不适当，致使结果偏大了6%左右（对较大速度星）。（2）没有考虑标准星轮廓中已经包含临边昏暗效应的影响这一因素，使结果偏大了约11%（对较大速度星）。而引力昏暗等效应的综合作用使老系统的值偏小了2-3%。在本文的§4，我们卷积法测出了五十多颗星的自转速度。用这些实测结果，我们得到下述结论：（1）在我们所用仪器条件下，当VeSini < 50KM/Sec时，临边昏暗效应对自转速度测定结果的影响很小，可忽略。但当VeSini ≥ 100KM/Sec时，该效应的影响比传统观点认为的要大得多，更进一步地，我们从理论上作了分析，得到了与实测一致的结论。理论上，对晚A、F星，临边昏暗效应的影响可达13%，（2）卷积法的测量结果与Slettebak新系统的值很好地符合：当VeSini ≤ 150KM/Sec时，两结果之间不存在明显差别；对VeSini > 200KM /Sec的星，卷积法的值平均比新系统的结果小2-3%。（3）尽管引力昏暗等效应的综合作用对谱线等值宽度的影响可达10%，但由于卷积法使用了整个谱线轮廓去求VeSini,它们对测量结果的综合影响的平均值仅为2-3%，即使对单个星，其影响也在5%以内。在文章的第五部份，我们探讨了建立新恒星自转速度定标系统的可能性。我们认为：卷积法适用范围广，资料处理快，观测对象多，内部符合好，精度较高等特征保证了它可以作为建立新定标系统的基本方法。并讨论了高速度星的椭球效应对测量结果的影响。在本文的最后部分，我们从进一步提高卷积法的测量精度，完善处理程序并使之能同时得到被测星的视向速度、元素丰度等方面进行了讨论，并提出了最终建立一个新的恒星自转速度定标系统，进而对原有的自转速度星表进行修订、扩充的工作计划。
英文摘要	A good few people think that the accuracy of Slettebak old system, which is used widely as the standard calibration system of stellar rotational velocities, is not ideal. This thesis is aimed at improving, go so far as to set up a new standard calibration system of stellar rotational velocities, and have analysed, discussed all determination method for stellar rotational velocities that we can collect. Also, we introduced their measurement principles and pratical effects, analysed their suit ranges, the main advantages and shortages. As the focal points, we have discussed mainly Slettebak old system, Slettebak new system which have good measurement accuracy but its calculation is very very costly, and the Convolving method, a new determination way of stellar rotational velocities, By statistics study, we have estimated out the difference between the old system and the new system quantitively: While the results of two systems do not show large difference for stars with V sin in smaller than 50KM/sec., The average V sinivalue in the new system is 15% lower than in the old system for B-, A-, F-stars with V sini larger than 150KM/sec.. Advancely, we have discussed the difference on the theory, and drawn following conculsiones: there are two weaks in Slettebak old system. (1) the limb-darkening cofficients chosen are not accurate, on the whole, the factor had made the measurement value of the system increase mistakenly 6% for stars with large V sii (2) Because the profile of standard (non-rotating) stars were obtained by observation. It did indeed contain the effect of limb-darkening, but th－calculation of the old system did not consider this factor. This would have made the V sini inciease about 11% averagely for stars with large V sini. On the other hand, the synthetical effect of grivaty darkening et al. effects will reduce the measurement value of rotational velocities about 2-3% averagely. In fourth part of the thesis, we have determined the rotational velocities of more 50 stay by the Convolving method. We also have analyse the date, and obtained conculsions: (1) on our instrument condition, the effect of limb-darkering on determination of stellar rotational vereities is very weak, may be ingored for stars with V sini smaller than 50KM/sec. However, for stars with V sini larger 100KM/sec. the effects much larger than one of traditional opinion thinks. On the theory, we also obtained same concultion. Our pure theory anaysis showed the effect may up to 13% for late A- and F-stars. (2) our results are very good agreement with the values of the new system for stars with V sini smaller 150KM/sec., While results of the new system is averagely larger 2-3% tham our measurement results for stars with V sini larger 200Km/sec. (3) Although the comprehensive effect of gravity darkening et al. may up to 10% on the equivalent width of lines the average effect of these fator on measurement is only 2-3%, even for singly star, the effect also is lower 5% as the Convolving method determinated V sini by the whole profile but the half width of line. In the fifth part of this thesis, We have discussed the probability of setting up a new standard calbrication system of stellar rotational velocities. We think that it is possible to set up a new system by the Convolving method as this method has many advantages. E.g. wide suit range, small internal error, good accuracy, fast calculation. we discussed the effect of ellipsoidal shape of large rotational velocity stars on the measurement Vsini. In the final part of the thesis, werdiscussed the convolving method from enhancing accuracy, improving the calculation program. We hope the improving program can find out rotational velocities, radial velocities, element abundance of measuremented stars simutaneously. We also gave a plan on further work.
语种	中文
学科主题	天文学
公开日期	2016-05-03
页码	158
内容类型	学位论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/4347]
专题	云南天文台_其他
推荐引用方式 GB/T 7714	潘开科. 恒星自转速度的测定[D]. 昆明. 中国科学院云南天文台. 1990.

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。