来自AAPS和凯克行星搜索调查的已知伴星宿主星的NACO-SDI成像
NACO-SDI imaging of known companion host stars from the AAPS and Keck planet search surveys
摘要：
将棕矮星作为太阳型恒星的伴星进行直接成像可以提供大量约束良好的数据来“基准”这些物体的物理学，因为像金属丰度和年龄这样的数量可以从它们经过充分研究的原色中确定。我们目前的结果，从一个自适应光学成像程序从英澳和凯克行星搜索项目绘制的恒星，直接成像已知的酷同伴的目的。利用从当前径向速度数据中获得的轨道参数估计值，模拟模拟了已知伴星的预期对比度和分离，然后对选定的最佳情况物体进行高对比度成像，试图直接对这些伴星成像。这些模拟表明，只有极少数具有一致速度拟合和年龄估计的径向速度检测到的系外行星可以使用VLT的同步差分成像系统直接成像，并且只有在有利的条件下。我们还提出了从径向速度数据集的可检测性置信限，并显示如何使用这些可以更好地了解这些系统时，结合成像数据。对于HD 32778和HD 91204，可探测性对限制伴星的帮助很小，因此我们几乎所有的知识都来自SDI图像。因此，我们可以说这些恒星没有冷的甲烷天体，天空中的距离约为2“，对比度小于10-11等。然而，对于HD 25874、HD 120780和HD 145825，对比度和可检测性可以排除许多可能的解决方案，特别是在低角间距下，并且对于最好的情况，在1“间距下低至40 MJ的强甲烷质量。这五颗恒星的对比度曲线显示，在间隔>/= 0.6“时，5 σ对比度（Δ F1）约为9.2-11.5等，对应于中T光谱型伴星的对比度约为9.7-12.0等。这样的限制使我们能够在相当古老的场矮星周围达到40 MJ，这些场矮星通常构成高精度径向速度程序。最后，这里进行的分析可以作为未来项目的模板，这些项目将采用极端AO系统直接对已经通过径向速度方法间接发现的行星进行成像。
英文摘要：
Direct imaging of brown dwarfs as companions to solar-type stars can provide a wealth of well-constrained data to "benchmark" the physics of such objects, since quantities like metallicity and age can be determined from their well-studied primaries. We present results from an adaptive optics imaging program on stars drawn from the Anglo-Australian and Keck Planet Search projects, with the aim of directly imaging known cool companions. Simulations have modeled the expected contrast ratios and separations of known companions using estimates of orbital parameters available from current radial-velocity data and then a selection of the best case objects were followed-up with high contrast imaging to attempt to directly image these companions. These simulations suggest that only a very small number of radial-velocity detected exoplanets with consistent velocity fits and age estimates could potentially be directly imaged using the VLT's Simultaneous Differential Imaging system and only under favorable conditions. We also present detectability confidence limits from the radial-velocity data sets and show how these can be used to gain a better understanding of these systems when combined with the imaging data. For HD32778 and HD91204 the detectabilities help little in constraining the companion and hence almost all our knowledge is drawn from the SDI images. Therefore, we can say that these stars do not host cool methane objects, out to on-sky separations of ~2'', with contrasts less than 10-11 magnitudes. However, for HD25874, HD120780 and HD145825, the contrasts and detectabilities can rule out a number of possible solutions, particularly at low angular separations, and for the best case, down to strong methane masses of 40MJ at 1'' separation. The contrast curves constructed for these five stars show 5 sigma contrasts (Delta F1) of ~9.2-11.5 magnitudes at separations of >/=0.6'', which correspond to contrasts of ~9.7-12.0 magnitudes for companions of mid-T spectral type. Such limits allow us to reach down to 40MJ around fairly old field dwarfs that typically constitute high precision radial-velocity programs. Finally, the analysis performed here can serve as a template for future projects that will employ extreme-AO systems to directly image planets already indirectly discovered by the radial-velocity method.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
