A review talk at the international conference "Binaries - Key to Comprehension of the Universe" Brno, Czech Rep. 8-12 June 2009. To appear in Dec.2010 as ASP-CS435, eds. A. Prsa and M. Zejda. This version as submitted to the editors
The survey of radial velocity orbits for short period (P < 1 day), bright (V < 10, with a few fainter stars) conducted at the David Dunlap Observatory in the last 9 years before its closure in 2008 included 162 binaries and resulted in 150 SB2 orbits and 5 SB1 spectroscopic orbits thus becoming one of the main legacies of DDO. The paper summarizes the main results from the survey.
Spectroscopic characterization of a sample of metal-poor solar-type stars from the HARPS planet search program. Precise spectroscopic parameters and mass estimation
Very metal-poor halo stars are the best candidates for being among the oldest objects in our Galaxy. Samples of halo stars with age determination and detailed chemical composition measurements provide key information for constraining the nature of the first stellar generations and the nucleosynthesis in the metal-poor regime.} Age estimates are very uncertain and are available for only a small number of metal-poor stars. Here we present the first results of a pilot program aimed at deriving precise masses, ages and chemical abundances for metal-poor halo giants using asteroseismology, and high…
The magnetic field of the hot spectroscopic binary HD5550
HD 5550是一颗光谱联星，由两颗A星组成，在BinaMIcS（各类恒星中的二元性和磁相互作用）大型计划的框架内与TBL的Narval一起观测。该系统的一个组成部分被发现是一个Ap星，具有令人惊讶的弱偶极场~65 G。伴星是一颗没有探测到磁场的Am星，偶极磁场的探测阈值约为40 G。该系统是潮汐锁定的，主要部件与轨道同步，但系统可能还没有完全圆化。这项工作只是第二次详细研究的磁场在一个热的短周期光谱双星。目前，在BinaMIcS项目中，TBL的Narval和CFHT的ESPaDOnS正在观察更多的系统，目的是了解磁性如何影响双星演化，反之亦然。
We performed photometric and spectroscopic investigations of NSVS 5029961 for the first time. The new BV(RI)$_c$-band light curves were obtained with the 1.0-m telescope at Weihai Observatory of Shandong University. Applying the Wilson-Devinney program, we found that NSVS 5029961 is an A-subtype shallow contact binary with extremely low mass ratio (q = 0.1515, f = 19.1\%). Six spectra have been obtained by LAMOST, and many chromospheric activity emission line indicators were detected in the spectra, revealing that the target exhibits strong chromospheric activity. We calculated the absolute pa…
The photometric analysis and spectroscopic study of the long period low mass ratio deep contact binary KN Per were executed. The light curves of BV(RI)$_c$-band were from the Ningbo Bureau of Education and Xinjiang Observatory Telescope (NEXT) at the Xingming Observatory. Through the analysis of Wilson-Devinney (W-D) program, KN Per was found as an A-type low mass ratio deep contact binary (q=0.236, f=53.4\%). A cool spot applied on the primary component was introduced to explain the unequal maxima of the light curve. Based on the O-C analysis, we found that the rate of the increasing orbital …
Elemental abundances of extrinsic carbon stars provide insight into the poorly understood origin and evolution of elements in the early Galaxy. In this work, we present the results of a detailed spectroscopic analysis of four potential carbon star candidates from the Hamburg/ESO Survey (HES) HE~0457$-$1805, HE~0920$-$0506, HE~1241$-$0337, and HE~1327$-$2116. This analysis is based on the high-resolution spectra obtained with Mercator/HERMES (R$\sim$86,000) and SUBARU/HDS (R$\sim$50,000). Although the abundances of a few elements, such as, Fe, C, and O are available from medium-resolution spect…
We started a program to search for companions around hybrid $δ$ Sct/$γ$ Dor stars with the frequency modulation method using Kepler data. Our best candidate was KIC 5709664, where we could identify Fourier peaks with sidelobes, suggesting binary orbital motion. We determined the orbital parameters with the phase modulation method and took spectroscopic measurements to confirm unambiguously the binary nature with radial velocities. The spectra show that the object is a double-lined spectroscopic binary, and we determined the orbital solutions from the radial velocity curve fit. The parameters f…
The STARK-B database as a resource for \textquotedblleft STARK" widths and shifts data: State of advancement and program of development
\textquotedblleft Stark "展宽理论和计算已经广泛发展了大约50年，现在可以应用于许多需求，特别是用于精确的光谱诊断和建模。这需要了解许多碰撞线轮廓。如今，通过在线数据库获取此类数据变得至关重要。STARK-B是贝尔格莱德天文台和天体物理学研究所（LERMA）之间的一个合作项目。它是一个数据库，计算了由于电子和离子碰撞（碰撞）而产生的原子和离子孤立线的宽度和位移。它致力于恒星大气和包层、实验室等离子体、激光设备和技术等离子体的建模和光谱诊断。因此，表中涵盖的温度和密度范围很广，取决于所考虑离子的电离度。STARK-B自2008年9月起全面开放，免费使用。第一阶段的开发工作于2012年秋季结束，因为所有使用碰撞半经典微扰方法和Sahal-Bréchot、Dimitrijević及其同事的代码计算的现有数据现已得到实施。我们现在开始了STARK-B的第二阶段开发。这里介绍了该数据库的发展状况和我们的开发计划，以及它在VAMDC中的背景。VAMDC（虚拟原子和分子数据中心）是一个国际联盟，它建立了一个安全，有文件记录，灵活的互操作平台电子科学，允许原子和分子数据的自动交换。
Accurate radial velocity determinations of optical emission lines (i.e. [NII]$λλ$6548,6584, H$α$, and [SII]$λλ$6717,6731) are very important for investigating the kinematics and dynamics properties of nebulae. The second stage survey program of Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) has started a sub-survey of nebulae (MRS-N) which will spectroscopically observe the optical emission lines of a large sample of nebulae near the Galactic plane. Until now, 15 MRS-N plates have been observed from 2017 September to 2019 June. Based on fitting the sky emission lines in the…
