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arXiv 1409.5897astro-ph.GAastro-ph.SR
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哈勃空间望远镜对WD 0806-661 B的近红外探测

Near-infrared Detection of WD 0806-661 B with the Hubble Space Telescope

K. L. Luhman, C. V. Morley, A. J. Burgasser T. L. Esplin, J. J. Bochanski

摘要:

WD 0806-661 B是目前已知最冷的棕矮星之一(T=300-345 K),这是根据斯皮策太空望远镜先前的中红外光度测量得出的。此外,它也是测试棕矮星理论模型的基准,因为它的年龄和距离受到其主星(2+/-0.5 Gyr,19.2+/-0.6 pc)的约束。我们提出了这个物体的第一个近红外探测,这是通过F110 W成像(~Y+J)与哈勃太空望远镜上的宽视场相机3实现的。我们测得织女星的星等为m110=25.70+/-0.08,这意味着J~25.0。当结合斯皮策测光时,我们对J的估计有助于更好地定义M4.5与J-[4.5]中最冷棕矮星的经验序列。WD 0806-661 B和其他Y矮星在该图中的位置与Burrows等人的多云模型和Saumon等人的无云模型最匹配,两者都采用化学平衡。Morley等人对50%云覆盖率的计算与数据只有微小的差异。光谱学可以对模型进行更严格的测试,但根据我们的F110 W测量,目前只有哈勃望远镜才能进行这样的观测,并且至少需要10个轨道才能达到约5的信噪比。

英文摘要:

WD 0806-661 B is one of the coldest known brown dwarfs (T=300-345 K) based on previous mid-infrared photometry from the Spitzer Space Telescope. In addition, it is a benchmark for testing theoretical models of brown dwarfs because its age and distance are well-constrained via its primary star (2+/-0.5 Gyr, 19.2+/-0.6 pc). We present the first near-infrared detection of this object, which has been achieved through F110W imaging (~Y+J) with the Wide Field Camera 3 on board the Hubble Space Telescope. We measure a Vega magnitude of m110=25.70+/-0.08, which implies J~25.0. When combined with the Spitzer photometry, our estimate of J helps to better define the empirical sequence of the coldest brown dwarfs in M4.5 versus J-[4.5]. The positions of WD 0806-661 B and other Y dwarfs in that diagram are best matched by the cloudy models of Burrows et al. and the cloudless models of Saumon et al., both of which employ chemical equilibrium. The calculations by Morley et al. for 50% cloud coverage differ only modestly from the data. Spectroscopy would enable a more stringent test of the models, but based on our F110W measurement, such observations are currently possible only with Hubble, and would require at least ~10 orbits to reach a signal-to-noise ratio of ~5.

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。

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