探索ONC的前主序列变量：新变量
Exploring pre-main sequence variables of ONC: The new variables
摘要：
自2004年以来，我们一直在从事一项长期观测计划，以监测猎户座星云团中的年轻恒星。我们已经收集了大约2000帧的V，R和I宽带过滤器在200多个夜晚分布在连续五个观测季节。高质量和时间延长的光度数据使我们有机会解决与年轻恒星相关的各种现象。该项目的主要动机是：i）探索非常年轻的低质量恒星中恒星磁活动的各种表现; ii）寻找新的主序前食双星; iii）寻找与YSO相关的任何EXor和FUor类似的瞬态活动。由于这是关于该计划的第一篇论文，我们对科学驱动因素，观察和数据简化策略进行了详细的描述。除了这些，我们还提出了大量的新的周期变量检测到我们的第一个五年的时间序列光度数据。我们的研究表明，我们的FoV中约72%的CTTS是周期性的，而周期性WTTS的百分比仅为32%。这表明ONC星CTTS表面的不均匀性图案比WTTS稳定得多。通过多年的监测发现，单季测光无法识别所有的周期变量。任何基于单季观测的角动量演化研究都必须谨慎进行。
英文摘要：
Since 2004, we have been engaged in a long-term observing program to monitor young stellar objects in the Orion Nebula Cluster. We have collected about two thousands frames in V, R, and I broad-band filters on more than two hundred nights distributed over five consecutive observing seasons. The high-quality and time-extended photometric data give us an opportunity to address various phenomena associated with young stars. The prime motivations of this project are i) to explore various manifestations of stellar magnetic activity in very young low-mass stars; ii) to search for new pre-main sequence eclipsing binaries; and iii) to look for any EXor and FUor like transient activities associated with YSOs. Since this is the first paper on this program, we give a detailed description of the science drivers, the observation and the data reduction strategies as well. In addition to these, we also present a large number of new periodic variables detected from our first five years of time-series photometric data. Our study reveals that about 72% of CTTS in our FoV are periodic, whereas, the percentage of periodic WTTS is just 32%. This indicates that inhomogeneities patterns on the surface of CTTS of the ONC stars are much more stable than on WTTS. From our multi-year monitoring campaign we found that the photometric surveys based on single-season are incapable of identifying all periodic variables. And any study on evolution of angular momentum based on single-season surveys must be carried out with caution.
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