Infrared Photometry of Late-M, L, and T Dwarfs
Infrared Photometry of Late-M, L, and T Dwarfs
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晚 M、L 和 T 矮星的红外光度测定
DOI：
10.1086/324037
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
D. York
中科院分区：
文献类型：
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作者：
S. Leggett;D. Golimowski;Xiaohui Fan;T. Geballe;G. Knapp;J. Brinkmann;I. Csabai;I. Csabai;J. Gunn;S. Hawley;T. Henry;T. Henry;R. Hindsley;Ž. Ivezić;R. Lupton;J. Pier;D. Schneider;J. A. Smith;M. Strauss;A. Uomoto;D. York
我们展示了 58 个晚期 M、L 和 T 矮星样本的 ZJHKL′M′ 光度测量，其中大部分是从斯隆数字巡天和两微米全巡天中识别出来的。 Geballe 等人的姊妹篇论文中介绍了大部分样品的近红外光谱和光谱分类。我们推导出样本中具有已知视差的 18 个矮星的光度，结果表明样本中 L 矮星的有效温度范围约为 2200-1300 K，T 矮星的有效温度范围为 1300-800 K。我们在英国红外望远镜获得了新的光度数据：Z 处有 42 个矮星，Z 处有 34 个矮星。 JHK，L' 处的 21 个矮星，以及两个 L 矮星和两个 T 矮星的 M' 数据。 M' 数据为该带通中的 L 和 T 矮星提供了首次精确的光度测量——对于 T2 和 T5 矮星，我们分别发现 K-M' = 1.2 和 1.6。这些颜色比已发表的模型预测的要蓝得多，这表明这些天体中的二氧化碳含量可能比预期的要丰富，正如 T6 矮星 GL 229B 中所发现的那样。我们还发现 K-L' 在大多数 M、L 和 T 子类中单调增加，但在 L6 和 T5 类型之间近似恒定，限制了其作为温度指示器的有用性。简并可能是由于 L' 带通蓝色边缘处 CH4 吸收的开始。 L 矮星的 JHK 颜色显示出显着的散射，表明这些带通中的通量对光球尘埃特性的变化敏感。后期 T 矮星的 H-K 颜色也显示出一些散射，我们认为这是由于压力引起的 H2 不透明度的变化造成的，而 H2 不透明度对重力和金属丰度敏感。
We present ZJHKL′M′ photometry of a sample of 58 late M, L, and T dwarfs, most of which are identified from the Sloan Digital Sky Survey and the Two Micron All-Sky Survey. Near-infrared spectra and spectral classifications for most of this sample are presented in a companion paper by Geballe et al. We derive the luminosities of 18 dwarfs in the sample with known parallaxes, and the results imply that the effective temperature range for the L dwarfs in our sample is approximately 2200-1300 K and for the T dwarfs 1300-800 K. We obtained new photometric data at the United Kingdom Infrared Telescope for: 42 dwarfs at Z, 34 dwarfs at JHK, 21 dwarfs at L', as well as M' data for two L dwarfs and two T dwarfs. The M' data provide the first accurate photometry for L and T dwarfs in this bandpass—for a T2 and a T5 dwarf, we find K-M′ = 1.2 and 1.6, respectively. These colors are much bluer than predicted by published models, suggesting that CO may be more abundant in these objects than expected, as has been found for the T6 dwarf Gl 229B. We also find that K-L' increases monotonically through most of the M, L, and T subclasses, but it is approximately constant between types L6 and T5, restricting its usefulness as a temperature indicator. The degeneracy is probably due to the onset of CH4 absorption at the blue edge of the L' bandpass. The JHK colors of L dwarfs show significant scatter, suggesting that the fluxes in these bandpasses are sensitive to variations in photospheric dust properties. The H-K colors of the later T dwarfs also show some scatter, which we suggest is due to variations in pressure-induced H2 opacity, which is sensitive to gravity and metallicity.