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arXiv 0710.5891astro-ph
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L 449-1的积分场光谱学--用SINFONI进行光谱微分成像的测试实例

Integral field spectroscopy of L 449-1 -- A test case for spectral differential imaging with SINFONI

Markus Janson, Wolfgang Brandner, Thomas Henning

备注：
9 pages, 9 figures, accepted for publication in A&A
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摘要：

光谱差分成像是一种越来越多地用于地面直接成像搜索棕矮星和恒星的行星质量伴星的技术。该技术利用了存在于这些冷物体中但不存在于恒星中的吸收特征，并且通常通过2至4个相邻通道中的同时窄带成像器来实现。然而，通过使用积分场单元，可以根据实际光谱使用不同的光谱特征，从而可能导致更大的灵活性和更强的检测限。本文介绍了利用VLT的SINFONI积分场装置对邻近的活动星L449-1进行光谱微分成像的试验结果。我们发现该方法在0.35”处提供了7.5等的3 σ对比度极限，这比NACO-SDI在相同的望远镜下使用相同的积分时间提供的对比度极限低1.5等。我们将讨论其原因及其影响。此外，我们使用SINFONI数据来约束的光谱类型的近红外光谱L 449-1，并找到一个结果之间的M3.0和M4.0，与以前的分类在可见光范围内的密切一致。

英文摘要：

Spectral differential imaging is an increasingly used technique for ground-based direct imaging searches for brown dwarf and planetary mass companions to stars. The technique takes advantage of absorption features that exist in these cool objects, but not in stars, and is normally implemented through simultaneous narrow-band imagers in 2 to 4 adjacent channels. However, by instead using an integral field unit, different spectral features could be used depending on the actual spectrum, potentially leading to greater flexibility and stronger detection limits. In this paper, we present the results of a test of spectral differential imaging using the SINFONI integral field unit at the VLT to study the nearby active star L449-1. No convincing companion candidates are found. We find that the method provides a 3 sigma contrast limit of 7.5 mag at 0.35", which is about 1.5 mag lower than for NACO-SDI at the same telescope, using the same integration time. We discuss the reasons for this, and the implications. In addition, we use the SINFONI data to constrain the spectral type in the NIR for L 449-1, and find a result between M3.0 and M4.0, in close agreement with a previous classification in the visual range.

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