Infrared Spectra and Spectral Energy Distributions of Late M and L Dwarfs
Infrared Spectra and Spectral Energy Distributions of Late M and L Dwarfs
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晚期 M 和 L 矮星的红外光谱和光谱能量分布
DOI：
10.1086/319020
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
A. Schweitzer
中科院分区：
文献类型：
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作者：
S. Leggett;F. Allard;T. Geballe;P. Hauschildt;A. Schweitzer
我们获得了光谱类型为 M6-L7 的 14 个盘矮星在 R ~ 600 处的 1.0-2.5 μm 光谱。对于其中四个矮星，我们还获得了 R ~ 3000 几个狭窄区间内的红外光谱。此外，我们还为样本中的四个矮星提供了新的 L' 光度测定法，这可以改进对其辐射光度的测定。在获得光度测定的同时，我们将 L 矮星 Denis-P J0205-1159 分解为一对相同的物体，彼此间隔 0.”35。将光谱以及另一颗 L5 矮星已发布的能量分布与升级模型大气生成的合成光谱进行比较。 2200 K ≥ Teff ≥ 1900 K（M9-L3 周围的光谱类型）具有良好匹配，但在 Teff ≥ 2300 K (M8) 和 Teff ≤ 1800 K (L4-L7) 时存在差异。在较高温度下，不匹配是由于水蒸气不透明度线列表不完整造成的。在较低温度下，这种分歧可能是由于我们对灰尘的处理造成的。我们假设光球分布与气相平衡并忽略任何扩散机制。我们通过与合成光谱的比较以及通过将观察到的总固有光度与结构模型计算进行比较（主要与大气无关，但取决于目标的未知质量和年龄）来得出样品的有效温度。这两个推导一致约为 200 K，但样本中最微弱的物体除外，该物体的差异较大。除 L7 矮星外，与其他温度测定的一致性也为 ±~200 K。
We have obtained 1.0-2.5 μm spectra at R ~ 600 of 14 disk dwarfs with spectral types M6-L7. For four of the dwarfs, we have also obtained infrared spectra at R ~ 3000 in several narrow intervals. In addition, we present new L' photometry for four of the dwarfs in the sample, which allows improved determinations of their bolometric luminosities. While obtaining the photometry we resolved the L dwarf Denis-P J0205-1159 into an identical pair of objects separated by 0.″35. The spectra together with the published energy distribution for one other L5 dwarf are compared to synthetic spectra generated by upgraded model atmospheres. Good matches are found for 2200 K ≥ Teff ≥ 1900 K (spectral types around M9-L3), but discrepancies exist at Teff ≥ 2300 K (M8) and Teff ≤ 1800 K (L4-L7). At the higher temperatures the mismatches are due to incompleteness in the water vapor opacity line list. At the lower temperatures the disagreement is probably due to our treatment of dust; we assume a photospheric distribution in equilibrium with the gas phase and neglect any diffusion mechanisms. We derive effective temperatures for the sample from the comparison with synthetic spectra and also by comparing our observed total intrinsic luminosities to structural model calculations (which are mostly independent of the atmosphere but are dependent on the unknown masses and ages of the targets). The two derivations agree to about 200 K except for the faintest object in the sample, where the discrepancy is larger. Agreement with other temperature determinations is also ±~200 K, except for the L7 dwarf.