标题： Wendelstein Calar Alto像素透镜项目（WeCAPP）：M31变星目录 显示英文标题

标题： The Wendelstein Calar Alto Pixellensing Project (WeCAPP): The M31 Variable Star Catalogue

摘要： 本文介绍了WeCAPP变星目录，该目录面向M31的核球。 WeCAPP微引力透镜巡天（光学R和I波段）三年（2000-2003年）的观测结果构成了一套前所未有的河外变星研究数据库。 我们在以M31核为中心的16.1'×16.6'区域内检测到23781个变源。 变星目录包含了位置、周期以及R和I波段的变化。 我们根据它们在R波段周期-振幅平面上的位置对变星进行了分类。 可以区分出三组；虽然前两组主要与造父型变星相关（第一组中的I型造父变星，第二组中的II型造父变星和RV天琴座星），第三组由长周期变星（LPVs）组成。 我们检测到了37颗RV天琴座星和11颗候选RV天琴座星，这是迄今为止此类恒星的最大集合之一。 分类方案得到了光变曲线傅里叶分解的支持。 我们的数据表明经典造父变星、II型造父变星和RV天琴座星的低阶傅里叶系数Φ_21与Φ_31之间存在相关性。 将我们的变星样本与Kaaret（2002年）和Kong等人（2002年）基于X射线的目录进行比对，得到23个和31个重合，其中8个是M31的球状星团。 探测到的变星数密度显然不对称，这必须纳入对M31方向预期微引力透镜事件率的计算中。 这种不对称性是由于M31旋臂中增强的消光叠加在核球上造成的，如果与亮度相当但无增强消光的区域相比，这会使源的数量减少约60%。 显示英文摘要

摘要： In this paper we present the WeCAPP variable star catalogue towards the bulge of M31. The observations of the WeCAPP microlensing survey (optical R and I bands) during three years (2000-2003) result in a database with unprecedented time coverage for an extragalactic variable star study. We detect 23781 variable sources in a 16.1' x 16.6' field centered on the nucleus of M31. The catalogue of variable stars contains the positions, the periods and the variations in the R and I bands. We classify the variables according to their position in the R-band period-amplitude plane. Three groups can be distinguished; while the first two groups can be mainly associated with Cepheid-like variables (population I Cepheids in group I, type II Cepheids and RV Tauri stars in group II), the third one consists of Long Period Variables (LPVs). We detect 37 RV Tauri stars and 11 RV Tauri candidates which is one of the largest collections of this class of stars to date. The classification scheme is supported by Fourier decomposition of the light curves. Our data shows a correlation of the low-order Fourier coefficients Phi_21 with Phi_31 for classical Cepheids, as well for type II Cepheids and RV Tauri stars. Correlating our sample of variable stars with the X-ray based catalogues of Kaaret (2002) and Kong et al. (2002) results in 23 and 31 coincidences, 8 of which are M31 globular clusters. The number density of detected variables is clearly not symmetric, which has to be included in the calculations of the expected microlensing event rate towards M31. This asymmetry is due to the enhanced extinction in the spiral arms superimposed on the bulge of M31 which reduces the number of sources to about 60%, if compared to areas of equivalent bulge brightness (without enhanced extinction being present).