Hot Subdwarf All Southern Sky Fast Transit Survey with the Evryscope
Hot Subdwarf All Southern Sky Fast Transit Survey with the Evryscope
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DOI：
10.3847/1538-4357/ab64f3
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发表时间：
2019-12
期刊：
影响因子：
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通讯作者：
J. Ratzloff;B. Barlow;P. Németh;H. Corbett;Stephen Walser;N. Galliher;A. Glazier;W. Howard
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文献类型：
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作者：
J. Ratzloff;B. Barlow;P. Németh;H. Corbett;Stephen Walser;N. Galliher;A. Glazier;W. Howard
我们对南部天空中的候选热亚矮星（HSD）进行了调查，寻找快速凌日、日食和 Evryscope 光变曲线的正弦变化。该调查的目的是探测从海王星大小的行星到气态巨行星的凌日信号，以及来自 M 矮星和褐矮星的日食信号。其他变异性信号主要预计来自致密双星和反射效应双星。由于 HSD 尺寸较小（R ≈ 0.2 R⊙），凌日和食信号预计仅持续约 20 分钟，但信号深度很大（如果方向为边缘，则可达完全食）。凭借 2 分钟的节奏和连续观测，Evryscope 能够很好地恢复这些快速的凌日和日食。尽管 HSD 目标很稀有，但超大视场 (8150 deg2) 对于获得足够的 HSD 目标至关重要。我们从 9.3 M Evryscope 光变曲线中识别出约 11,000 个潜在 HSD，这些光源亮度高于 mg = 15。通过我们的机器学习光谱分类器，我们标记了高置信度目标，并估计调查中的 HSD 总数为约 1400 个。光曲线搜索发现了三颗凌日候选行星，后续分析表明它们有恒星伴星。我们发现了几个新的致密双星（包括两个具有看不见的简并伴星）、两个具有M矮星伴星的食双星，以及新的反射效应双星和其他具有类似正弦变化的双星。其中四项发现正在单独的后续论文中发表，我们讨论了其他发现的后续潜力。
We have conducted a survey of candidate hot subdwarf (HSD) stars in the southern sky searching for fast transits, eclipses, and sinusoidal-like variability in the Evryscope light curves. The survey aims to detect transit signals from Neptune-size planets to gas giants, and eclipses from M-dwarfs and brown dwarfs. The other variability signals are primarily expected to be from compact binaries and reflection effect binaries. Due to the small size of HSDs (R ≈ 0.2 R⊙), transit and eclipse signals are expected to last only ≈20 minutes, but with large signal depths (up to completely eclipsing if the orientation is edge on). With its 2 minute cadence and continuous observation, the Evryscope is well placed to recover these fast transits and eclipses. The very large field of view (8150 deg2) is critical to obtain enough HSD targets, despite their rarity. We identified ≈11,000 potential HSDs from the 9.3 M Evryscope light curves for sources brighter than mg = 15. With our machine-learning spectral classifier, we flagged high confidence targets and estimate the total HSDs in the survey to be ≈1400. The light-curve search detected three planet transit candidates, shown to have stellar companions from follow-up analysis. We discovered several new compact binaries (including two with unseen degenerate companions), two eclipsing binaries with M-dwarf companions, as well as new reflection effect binaries and others with sinusoidal-like variability. Four of the discoveries are being published in separate follow-up papers, and we discuss the follow-up potential of the other discoveries.