Meeting the Cool Neighbors. XII. An Optically Anchored Analysis of the Near-infrared Spectra of L Dwarfs
Meeting the Cool Neighbors. XII. An Optically Anchored Analysis of the Near-infrared Spectra of L Dwarfs
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认识酷邻居。
DOI：
10.3847/1538-3881/aa9d8a
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
D. Looper
中科院分区：
文献类型：
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作者：
K. Cruz;A. Núñez;A. Burgasser;E. Abrahams;E. Rice;I. Reid;D. Looper
竞争L矮星的光学和近红外（NIR）光谱分型系统之间的差异促使我们寻找一个分类方案，将光学和NIR方案联系在一起，并解决光谱形态的复杂性。我们使用新的和现存的光学和近红外光谱汇编了171个L矮星的样本，包括27个低重力β和γ天体，光谱覆盖范围从0.6-2.4 μm。我们提出了155个新的低分辨率近红外光谱和19个新的光谱。我们利用一种方法来分析近红外光谱，部分地消除了宽带光谱斜率，并揭示了相同的光学光谱类型的对象之间的吸收功能的相似性。利用光谱作为锚，我们生成了L0-L 8，L0-L4γ和L0-L1β型矮星的近红外光谱平均模板。这些模板揭示了近红外光谱形态与光学类型相关。它们还显示了每种光谱类型所跨越的光谱形态的范围。我们比较低重力和场重力模板，提供建议的最低要求的观测合理分类低重力光谱使用低分辨率近红外数据。我们使用模板来评估现有的近红外光谱标准，并在适当的情况下提出新的。最后，我们建立在柯克帕特里克等人的工作。提供一个光谱分型方法，是绑在光学和可以使用时，只有H或K波段的数据。我们在这里提出的方法提供了几个长期存在的问题与分类L矮光谱的解决方案，也可以为云系外行星的光谱分类方案的基础。
Discrepancies between competing optical and near-infrared (NIR) spectral typing systems for L dwarfs have motivated us to search for a classification scheme that ties the optical and NIR schemes together, and addresses complexities in the spectral morphology. We use new and extant optical and NIR spectra to compile a sample of 171 L dwarfs, including 27 low-gravity β and γ objects, with spectral coverage from 0.6–2.4 μm. We present 155 new low-resolution NIR spectra and 19 new optical spectra. We utilize a method for analyzing NIR spectra that partially removes the broad-band spectral slope and reveals similarities in the absorption features between objects of the same optical spectral type. Using the optical spectra as an anchor, we generate near-infrared spectral average templates for L0–L8, L0–L4γ, and L0–L1β type dwarfs. These templates reveal that NIR spectral morphologies are correlated with the optical types. They also show the range of spectral morphologies spanned by each spectral type. We compare low-gravity and field-gravity templates to provide recommendations on the minimum required observations for credibly classifying low-gravity spectra using low-resolution NIR data. We use the templates to evaluate the existing NIR spectral standards and propose new ones where appropriate. Finally, we build on the work of Kirkpatrick et al. to provide a spectral typing method that is tied to the optical and can be used when only H or K band data are available. The methods we present here provide resolutions to several long-standing issues with classifying L dwarf spectra and could also be the foundation for a spectral classification scheme for cloudy exoplanets.