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arXiv 1104.1382astro-ph.SR
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附近主序星的外黄尘水平

Exo--Zodiacal Dust Levels for Nearby Main Sequence Stars

R. Millan-Gabet, E. Serabyn, B. Mennesson, W. A. Traub, R. K. Barry, W. C. Danchi, M. Kuchner, S. Ragland, M. Hrynevych, J. Woillez, K. Stapelfeldt, G. Bryden, … 展开作者

R. Millan-Gabet, E. Serabyn, B. Mennesson, W. A. Traub, R. K. Barry, W. C. Danchi, M. Kuchner, S. Ragland, M. Hrynevych, J. Woillez, K. Stapelfeldt, G. Bryden, M. M. Colavita, A. J. Booth

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摘要：

Keck干涉仪Nuller（KIN）被用来调查25个附近的主序星在中红外线，以评估附近的太阳型恒星周围的温暖拱星（exozodiacal）尘埃的流行。KIN测量星周辐射的方法是在空间上阻挡恒星，但在距离恒星0.1 - 4天文单位的区域内传输星周辐射。我们发现一个显着的检测（eta Crv），两个边缘检测（伽马Oph和阿尔法Aql），和22个明确的非检测。使用我们自己的太阳系的黄道带云模型，缩放到每个目标恒星的光度，我们估计需要匹配我们的观测的目标黄道带的等效数量。我们的三个zodi检测是eta Crv（1250 +/- 260），gamma Oph（200 +/- 80）和alpha Aql（600 +/- 200），其中不确定性为1-sigma。22个未检测到的目标具有与零一致的总体加权平均值，平均个体不确定性为160佐迪斯（1-西格玛）。这些测量代表了迄今为止对附近主序星样本的exozodi水平的最佳限制。对先前不知道含有星周尘埃的23颗恒星的统计分析（不包括eta Crv和gamma Oph）表明，如果测量误差不相关，（我们提供了证据），如果这23颗恒星代表了一个单一的类的exozodi亮度水平，则该类的平均exozodi水平<150 zodis（3-sigma上限，对应于测量误差为高斯分布的额外假设下的99%置信度）。我们还证明，这一结论在很大程度上是独立的形状和平均水平（未知）真正的基础exozodi分布。

英文摘要：

The Keck Interferometer Nuller (KIN) was used to survey 25 nearby main sequence stars in the mid-infrared, in order to assess the prevalence of warm circumstellar (exozodiacal) dust around nearby solar-type stars. The KIN measures circumstellar emission by spatially blocking the star but transmitting the circumstellar flux in a region typically 0.1 - 4 AU from the star. We find one significant detection (eta Crv), two marginal detections (gamma Oph and alpha Aql), and 22 clear non-detections. Using a model of our own Solar System's zodiacal cloud, scaled to the luminosity of each target star, we estimate the equivalent number of target zodis needed to match our observations. Our three zodi detections are eta Crv (1250 +/- 260), gamma Oph (200 +/- 80) and alpha Aql (600 +/- 200), where the uncertainties are 1-sigma. The 22 non-detected targets have an ensemble weighted average consistent with zero, with an average individual uncertainty of 160 zodis (1-sigma). These measurements represent the best limits to date on exozodi levels for a sample of nearby main sequence stars. A statistical analysis of the population of 23 stars not previously known to contain circumstellar dust (excluding eta Crv and gamma Oph) suggests that, if the measurement errors are uncorrelated (for which we provide evidence) and if these 23 stars are representative of a single class with respect to the level of exozodi brightness, the mean exozodi level for the class is <150 zodis (3-sigma upper-limit, corresponding to 99% confidence under the additional assumption that the measurement errors are Gaussian). We also demonstrate that this conclusion is largely independent of the shape and mean level of the (unknown) true underlying exozodi distribution.

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