An HST search for planets in the lower main sequence of the globular cluster NGC 6397
An HST search for planets in the lower main sequence of the globular cluster NGC 6397
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DOI：
10.1051/0004-6361/201118655
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发表时间：
2012-02
影响因子：
6.5
通讯作者：
V. Nascimbeni;V. Nascimbeni;L. Bedin;L. Bedin;G. Piotto;F. Marchi;R. Rich
中科院分区：
文献类型：
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作者：
V. Nascimbeni;V. Nascimbeni;L. Bedin;L. Bedin;G. Piotto;F. Marchi;R. Rich
迄今为止，在疏散星团和球状星团中进行的行星凌日研究只产生了少数几个微弱的、未经证实的候选者。这些结果被解释为要么是微不足道的，要么是集群化学或动力学环境抑制行星形成或生存的证据。大多数活动都受到小样本统计或地面测光系统的限制。我们在NGC 6397的126个轨道上进行了一次凌日行星和变星的搜索。我们分析了5078条光变曲线，包括精心挑选的2215个M0-M9矮星。针对系统趋势对光变曲线进行了校正，并使用多种工具进行了检查。没有发现高重要性的行星候选者。我们将这个零检测与开普勒的最新结果进行了比较，表明没有确凿的证据表明行星的入射率较低。然而，对于早期M集群成员测量到非常小的光度抖动（其中98%为2 mmag），这可能值得在不久的将来进行更优化的活动。12颗变星是首次报道。
Searches for planetary transits carried out in open and globular clusters have to date yielded only a handful of weak, unconfirmed candidates. These results have been interpreted as either being insignificant, or evidence that the cluster chemical or dynamical environment inhibits planetary formation or survival. Most campaigns have been limited by small sample statistics or systematics from ground-based photometry. We performed a search for transiting planets and variables in a deep stellar field of NGC 6397 imaged by HST-ACS over 126 orbits. We analyzed 5078 light curves, including a careful selection of 2215 cluster-member M0–M9 dwarfs. The light curves were corrected for systematic trends and inspected using several tools. No high-significance planetary candidate is detected. We compared this null detection with the most recent results from Kepler, showing that no conclusive evidence of lower planet incidence can be drawn. However, a very small photometric jitter is measured for early-M cluster members (2 mmag on 98% of them), which may be worth targeting in the near future with more optimized campaigns. Twelve variable stars are reported for the first time.