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arXiv 1111.1168astro-ph.EPastro-ph.SR
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SOPHIE搜寻北系外行星。IV。行星-褐矮星边界中的大质量伴星

The SOPHIE search for northern extrasolar planets. IV. Massive companions in the planet-brown dwarf boundary

R. F. Díaz, A. Santerne, J. Sahlmann, G. Hébrard, A. Eggenberger, N. C. Santos, C. Moutou, L. Arnold, I. Boisse, X. Bonfils, F. Bouchy, X. Delfosse, M. Desort, … 展开作者

R. F. Díaz, A. Santerne, J. Sahlmann, G. Hébrard, A. Eggenberger, N. C. Santos, C. Moutou, L. Arnold, I. Boisse, X. Bonfils, F. Bouchy, X. Delfosse, M. Desort, D. Ehrenreich, T. Forveille, A. M. Lagrange, C. Lovis, F. Pepe, C. Perrier, D. Queloz, D. Ségransan, S. Udry, A. Vidal-Madjar

摘要:

大质量太阳系外行星和褐矮星所在的质量域仍然知之甚少。事实上,大质量行星和褐矮星之间甚至还没有明确的分界线。这部分是由于缺乏这种靠近太阳型恒星的天体,即所谓的褐矮星沙漠,这阻碍了建立一个强大的观测基础,以比较形成和演化的模型和理论。我们的搜索,以增加当前的大规模的亚恒星物体的样本与精确的轨道参数,并限制检测到的亚恒星候选人的真实质量。亚恒星候选者的初步识别是使用上普罗旺斯天文台1.93米望远镜的索菲摄谱仪获得的精确径向速度测量结果完成的。这些候选者的后续表征,主要目的是确定在低倾角轨道的恒星同伴,是通过不同的光谱诊断,作为平分线速度跨度的测量和相关掩模效应的研究。为了实现这一目标,我们还采用了依巴谷任务的天体测量数据和一种模拟恒星交叉关联函数的新方法。探测到7个最小质量在~10 Mjup和~90 Mjup之间的新天体。其中两颗被确认为低轨道倾角的低质量恒星,另外两颗的质量低于理论上的氘燃烧极限,因此是行星候选者。剩下的三颗是褐矮星候选者;目前它们的质量上限不允许我们对它们的性质做出结论。此外,我们还改进了已知的棕矮星(HD 137510 b)的参数,并通过天体测量证实。

英文摘要:

The mass domain where massive extrasolar planets and brown dwarfs lay is still poorly understood. Indeed, not even a clear dividing line between massive planets and brown dwarfs has been established yet. This is partly due to the paucity of this kind of objects orbiting close to solar-type stars, the so-called brown dwarf desert, that hinders setting up a strong observational base to compare to models and theories of formation and evolution. We search to increase the current sample of massive sub-stellar objects with precise orbital parameters, and to constrain the true mass of detected sub-stellar candidates. The initial identification of sub-stellar candidates is done using precise radial velocity measurements obtained with the SOPHIE spectrograph at the 1.93-m telescope of the Haute-Provence Observatory. Subsequent characterisation of these candidates, with the principal aim of identifying stellar companions in low-inclination orbits, is done by means of different spectroscopic diagnostics, as the measurement of the bisector velocity span and the study of the correlation mask effect. With this objective, we also employed astrometric data from the Hipparcos mission and a novel method of simulating stellar cross-correlation functions. Seven new objects with minimum masses between ~ 10 Mjup and ~90 Mjup are detected. Out of these, two are identified as low-mass stars in low-inclination orbits, and two others have masses below the theoretical deuterium-burning limit, and are therefore planetary candidates. The remaining three are brown dwarf candidates; the current upper limits for their the masses do not allow us to conclude on their nature. Additionally, we have improved on the parameters of an already-known brown dwarf (HD137510b), confirmed by astrometry.

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