KMS of Xinjiang Astronomical Observatory, CAS
| 疏散星团NGC 2355及其附近天区的变星搜寻与研究 | |
| Alternative Title | Searching Variables Stars in the Open Cluster NGC 2355 and Its Surrounding Region |
王红
| |
| Subtype | 硕士 |
| Thesis Advisor | 张余 |
| 2022-05-25 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Name | 理学硕士 |
| Degree Discipline | 天体物理 |
| Keyword | 疏散星团，NGC 2355，南山一米大视场光学望远镜，变星，星 团参数 |
| Abstract | 恒星内部结构与演化的研究是奠定现代天体物理研究的基石，也是最基础的天文研究之一。对变星的研究可以提供大量的恒星参数等信息，如质量、半径、亮度、温度、内部和外部结构等，这些参数与恒星理论模型紧密结合，从而帮助我们开展更深入的研究。这些恒星的参数信息在除了变星以外的恒星中是很难甚至不可能获得的。而疏散星团是了解和研究基本天体物理过程的理想实验室，也是银河系的重要组成部分之一，其中包含了种类丰富的变星且大多数成员星都处于主序阶段。疏散星团内的变星与疏散星团有着同源性，它们都诞生于同一分子云，具有大致相同的化学丰度、年龄、空间分布和运动学特征。因此，疏散星团及其变星的广泛研究对于推断银河系的恒星形成历史和探测银河系的结构是至关重要的。 疏散星团NGC 2355作为银河系中位于反银心方向且遥远的疏散星团，本研究工作使用中国科学院新疆天文台南山一米大视场光学望远镜对其进行了历时两年、长达13天的测光观测，累计获得了超过3000张V波段的CCD图像数据。利用这些时序巡天测光观测图像数据，对疏散星团NGC 2355及其附近天区的变星进行了搜寻与研究。本工作详细介绍了研究目标的背景、观测设备与数据处理、变星的搜寻与判定，以及疏散星团参数信息的获取。通过利用基于IRAF和SExtractor软件包编写的XAO时域巡天数据处理pipeline对图像数据进行处理，得到视场中所有星的测光数据，再通过星等改正以及大视场时域巡天变星搜寻等方法将这些测光数据进行整合分析，最终在疏散星团NGC 2355及其附近天区探测到了88颗变星。这88颗变星中有72颗是我们新发现的变星，剩余16颗是已知变星。根据它们周期、振幅、有效温度等相关信息，再结合它们各自的光变曲线形态，将它们分为各种不同类型的变星，其中包含26颗食双星（9颗EA型食双星，6颗EB型食双星以及11颗EW型食双星），52 颗脉动变星（38颗𝛿 Scuti变星，3颗𝛾 Dor变星，9颗天琴座RR变星以及2颗造父I型变星），4颗旋转变星和6颗未知类型的变星。 本工作还参考了Cantat-Gaudin 等 (2018)利用Gaia DR2高精度测光及运动学数据结合Unsupervised Photometric Membership Assignment in Stellar Clusters（UPMASK）聚类算法给出的疏散星团NGC 2355的328颗成员星，并对疏散星团的变星成员星性进行了研究。在与Cantat-Gaudin 等 (2018)给出的328颗成员星交叉匹配后，得到在这88颗变星中有11颗变星为成员星。除此之外，为了找到星团外围可能被遗漏的变星成员星，本研究工作还对疏散星团NGC 2355的成员星以及探测到的88颗变星的空间分布、自行空间分布、视差以及运动学方面进行了分析，发现在本工作找到的非成员星变星中，有4颗可能是疏散星团NGC 2355被漏掉的成员星变星候选体。最后，我们结合对疏散星团NGC 2355的多色测光数据，给出了该星团的红化值，再结合相关研究给出的金属丰度值，利用等年龄线拟合的方法，给出了星团参数：log(Age/yr) = 8.9，E(B - V) = 0.24，[Fe/H] = - 0.07 dex。 |
| Other Abstract | The study of the structure and evolution of stars is one of the most fundamental astronomical studies that laid the cornerstone of modern astrophysical research. The study of variable stars can provide a great deal of extra information that allows us to tighten the screws on theoretical models attempting to predict stellar properties, such as mass, radius, brightness, temperature, internal and external structure, some of which are difficult or impossible to obtain in stars other than variable stars. Open clusters are exceptional laboratories for us to understand the fundamental astrophysical processes and one of the principal components of the Galaxy. Most of the open clusters are in the main sequence stage and contain a rich variety of variable stars. Therefore, extensive studies of open clusters and their variable stars are essential to infer the star formation history of the Milky Way and to probe the structure of the Galaxy. The open cluster NGC 2355 is situated in the anti-center direction of the Galaxy, in the constellation of Gemini. We have obtained more than 3000 V band CCD images from 13 days of photometric observations using the Nanshan One-meter Wide-field Telescope of the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences in two years. These time-series photometric observations are used to search and study the variable stars in the open cluster NGC 2355 and its surrounding sky region. This work presents in detail the background of the study target, the observation equipment and data processing, the search and determination of variable stars, and the acquisition of information on the parameters of the open cluster. The image data are processed by the XAO time-domain survey data processing pipeline based on the IRAF and SExtractor software packages to get all of the stars in the field of view. Then the photometric data are integrated and analyzed by magnitude correction and large field time-domain survey variable star search, as a result, 88 variable stars were detected in the open cluster NGC 2355 and its surrounding. Of these 88 variable stars, 72 are new discoveries and the remaining 16 are known variable stars. Based on their periods, amplitudes, effective temperatures, and other relevant information, combined with their respective light curve patterns, they are classified into various types of variable stars, including 26 eclipsing binaries (9 EA-type, 6 EB-type, and 11 EW-type eclipsing binaries), 52 pulsating variable stars (38 𝛿 Scuti variables, 3 𝛾 Dor variables, 9 Lyrae RR variables, and 2 Type I Cepheid variables), 4 rotating variable stars, and 6 unclear type variable stars. Cantat-Gaudin et al. (2018) used Gaia DR2 high precision photometric and kinematic data combined with the Unsupervised Photometric Membership Assignment in Stellar Clusters (UPMASK) clustering algorithm to give the 328 member stars of open cluster NGC 2355. Employing Gaia DR2 parallax, kinematics, and photometry, the cluster membership of these variable stars were also analyzed for NGC 2355. After cross-matching with the 328 member stars given by Cantat-Gaudin et al. (2018), 11 variable stars are obtained as member stars among the 88 variable stars. In addition to the 11 variable members reported by Cantat-Gaudin et al. (2018), we identify 4 more variable member candidates located at the outer region of NGC 2355 and showed homogeneity in space positions and kinematic properties with the cluster members. Finally, we combine the multi-color photometry data of the open cluster NGC 2355 to give the reddening values of the open cluster, and then combine the metal abundance values given by related studies to give the cluster parameters using isochrones fitting: log(Age/yr) = 8.9, E(B - V ) = 0.24, [Fe/H] = - 0.07 dex. |
| Pages | 64 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xao.ac.cn/handle/45760611-7/5167 |
| Collection | 研究生学位论文 光学天文与技术应用研究室_星团与星系研究团组 |
| Affiliation | 中国科学院新疆天文台 |
| First Author Affilication | Xinjiang Astronomical Observatory, Chinese Academy of Sciences |
| Recommended Citation GB/T 7714 | 王红. 疏散星团NGC 2355及其附近天区的变星搜寻与研究[D]. 北京. 中国科学院大学,2022. |
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| 疏散星团NGC 2355及其附近天区的变（11687KB） | 学位论文 | 暂不开放 | CC BY-NC-SA | Application Full Text | ||
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