| 类太阳G型密近双星的观测与研究 |
| 其他题名 | Observation and Investigation on G-type Solar-like Close Binaries
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| 王晶晶
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| 学位类型 | 博士
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| 导师 | 钱声帮
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| 2015-07-01
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| 学位授予单位 | 中国科学院研究生院
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| 学位授予地点 | 北京
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| 学位专业 | 天体物理
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| 关键词 | 类太阳
密近双星
磁场活动
轨道周期
第三天体
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| 摘要 | 类太阳G型密近双星中两子星均为晚型星,表现出许多比太阳强烈的磁场活动,如X射线发射、大面积黑子和耀斑活动等。对这些系统进行长期监测与研究,有助于我们更好地认识极端物理条件(快速自转、公共包层等)下类太阳磁场活动和类太阳恒星的演化特征。本文首先介绍了类太阳G型密近双星的研究背景、意义及方法;然后阐述了几颗类太阳G型相接、半接系统的观测与研究;最后对Kepler食双星中类太阳G型双星进行统计分析,并给出部分类太阳G型Kepler双星的初步结果。具体研究成果如下:1、对比不同几何结构双星的光变曲线,发现部分系统曲线短时间内存在变化,其畸变幅度的可能关系为:分离>半接>相接。根据现有一些理论分析,这些畸变可能源于子星表面的黑子、耀斑等磁场活动,它们可能引起子星半径、温度的变化,进而影响公共包层演化。为更好地认识磁场活动与子星演化特征,先后利用Fortran语言在Wilson-Devinney程序基础上编写质量比搜寻和自动求解程序,有助于我们提高测光解轨的运算速度和计算精度。2、对类太阳G型相接双星CW Cas、GN Boo以及V2284 Cyg的光变曲线进行分析,结果表明CW Cas曲线的O’Connell效应在2004年出现,2011年几乎消失;而在2010到2013年监测中,GN Boo的O’Connell效应出现同样的变化,并且主次极小深度差在逐年增长;V2284 Cyg数据来源于Kepler太空望远镜,光变曲线畸变可能是由于耀斑活动,但也不排除是望远镜观测误差引起的。光变曲线的畸变(短时间变化)可能是子星表面磁场活动的证据。利用WD程序,对它们的光变曲线进行测光解轨,发现2011年CW Cas子星表面黑子较2004年位置不变,面积变小;GN Boo主星表面黑子是变化的;V2284 Cyg不存在黑子活动。通过对比三颗相接双星基本参数,推测公共包层可能与磁场活动相互影响:公共包层抑制磁场活动,而磁场活动会使得子星外半径发生变化,进而影响公共包层变厚或变薄。另外,分别对三颗系统进行轨道周期分析,发现它们的轨道周期都存在周期性震荡,其可能由于第三天体的光时轨道效应。3、2010年对类太阳G型半接双星BU Vul进行连续四个月的观测,发现该系统的光度畸变程度较大,特别是O’Connell效应变化明显。考虑BU Vul首次进行测光研究,利用2010年9月多波段完整的光变曲线进行质量比搜寻,认为BU Vul的质量比q在0.40附近,因此该系统是一颗小质量星充满的半接双星。依据测光解轨中黑子参数,发现子星表面可能存在耀斑和黑子。结合CCD测光极小时刻,发现系统轨道周期为周期性变化和长期增长。轨道周期的长期增长可能是由于质量以dM2/dt=-3.10×10-8M⊙year-1的速率从小质量星转移到大质量星,而周期性震荡可能是第三天体的光时轨道效应引起。另在2009年11月4日对其主极小进行观测时,发现光变曲线在0.05相位出现畸变,畸变星等与次星星等接近,其可能源于第三天体以外的其他天体,因此BU Vul可能是多星系统。另外给出类太阳G型Algol系统1RXS J201607.0+251645详细的调研分析,发现该系统光变曲线在短时间内变化非常明显且可能存在周期性。1RXS J201607.0+251645是研究G型Algol双星类太阳活动的优秀样本。4、对近2500颗Kepler食双星进行统计分析,发现大部分双星表面温度为5000 K～6000 K;其中类太阳G型Kepler双星中分离系统占近70%,轨道周期小于10天的双星占67%。而轨道周期小于1天的双星中,大多数双星轨道周期分布在0.3天～0.4天。同时在一些类太阳G型Kepler双星,发现了耀斑以及O’Connell效应,特别是30天内KIC 8481574光变曲线存在与GN Boo类似的主次极小星等差渐变过程。利用最小二乘法计算主次极小、极大与O-C值,发现轨道周期的变化与光度畸变不存在相关性。 |
| 其他摘要 | The components of G-type solar-like close binaries are late-type stars, which exhibit stronger magnetic activities than that sun does, e.g., X-ray mission, stellar spots, and flares. The long-term monitoring on these systems are helpful for understanding the magnetic activities and evolutions of solar-like stars in extreme physical conditions(fast rotation, common convective envelop). In this paper, the background, significance, and methods of G-type close binaries are introduced in the first section. Later, we carried out the photometric investigations on some contact and semi-detached binaries. At last, the statistical studies and simple analysis of Kepler G-type close binaries are presented. All results are obtained as follows: 1、There are short-time variations of light curves for different geometrical binary systems. Compared with these curves, it was found the range of variations have the following relations, detached > semi-detached > contact. Based on some present theories, the curve variations are possibly due to magnetic activities, which have effect on the radius of the components or the common convective envelop. In order to analyze these curves by using Wilson-Devinney code efficiently, we compiled some programs to derive photometric solutions. 2、According to the photometric analysis on G-type contact binaries, CW Cas, GN Boo, and V2284 Cyg, O’Connell effect of CWCas in 2004 disappeared in 2011; for GN Boo, O’Connell effect occurred on 5th , May 2011, and the difference between the primary and secondary minimum increased gradually from 2010 to 2013. The flare-like events are found for V2284 Cyg, but it need to shortexposure observations to confirm these. By using the W-D code, we derive their photometric solutions. The dark spot of CW Cas in 2011 are smaller than that in 2004; spots on the surface of the primary component for GN Boo are variable. These investigations suggested the common envelop inhibits magnetic activities; the magnetic activities may influence the outer radius of the components, and further lead to the common envelop to vary. Meanwhile, the variations of their orbital periods show the periodical oscillation, which is explained as the presence of the third body. 3、The multi-color CCD photometric observations of the Algol-type binary BU Vul were carried out in 2010, June, July, August, and September, respectively. It was found that the obvious variations and asymmetry of light curves on the timescale of month, indicating high-level stellar spot activities on the surface of at least one component. The photometric solutions suggest that BU Vul is a semidetached binary with the cool, less massive component filling with the critical Roche-lobe. Meanwhile, all CCD times of light minimum were analyzed the orbital period variations. From the O–C curves, its orbital period shows a cyclic oscillation (T3=24.5 yr, A3=0.0131 days) superposed on the secular increase. The continuous increasing is possibly as a result of mass transfer from the less massive component to the more massive one at a rate of dM/dt = ?2.16×10?7M⊙ year?1. A probable eclipse-like event was observed on November 4th, 2009, what hints that BU Vul has the possibility to be in a quadruple system. From the surveys on 1RXS J201607.0+251645, its light curves are variable, especially for the maximum light. This phenomenon is possible for magnetic activity on the surface of the components. 4、Based on more than 2500 binaries from Kepler space telescope, we obtained some results, 1) most of temperatures of close binaries range from 5000 K to 6000 K; 2) G-type solar-like detached binaries cover nearly to 70%, number of period less than 10 days up to 67%; 3) the most period of G-type close binaries are between 0.3 days and 0.4 days. The third body was found from the continuous curves or O ? C diagram, we also desire to find magnetic activities. Some G-type close binaries show flares O’Connell effect. Especially, the difference of minimum light for KIC 8481574 are similar with that of GN Boo. By the least square method, we calculated the magnitudes of extreme light and the variations of the orbital period, which were found to be uncorrelated. |
| 学科领域 | 天文学
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| 语种 | 中文
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| 文献类型 | 学位论文
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| 条目标识符 | http://ir.ynao.ac.cn/handle/114a53/9455
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| 专题 | 双星与变星研究组
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| 作者单位 | 中国科学院云南天文台
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推荐引用方式
GB/T 7714 |
王晶晶. 类太阳G型密近双星的观测与研究[D]. 北京. 中国科学院研究生院,2015.
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