AKARI OBSERVATIONS OF BROWN DWARFS. III. CO, CO_2 and CH_4 FUNDAMENTAL BANDS AND PHYSICAL PARAMETERS
AKARI OBSERVATIONS OF BROWN DWARFS. III. CO, CO_2 and CH_4 FUNDAMENTAL BANDS AND PHYSICAL PARAMETERS
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AKARI 对褐矮星的观测。
DOI：
10.1088/0004-637x/760/2/151
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
I. Yamamura
中科院分区：
文献类型：
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作者：
S. Sorahana;I. Yamamura
本文研究了AKARI观测到的16个褐矮星光谱中CH 4、CO和CO2三个分子带的强度变化。光谱特征沿着从L1到T8的源类序列进行检查。我们发现在L5以后的棕矮星光谱中出现了CH43.3 μm带，而在所有的光谱类型中都出现了CO4.6 μm带。在晚L型和T型矮星中检测到4.2 μm处的CO2吸收带。为了更好地理解棕矮星大气，我们使用统一云模型分析了观测到的光谱。AKARI样品的物理参数，即大气有效温度Teff，表面重力log g，和临界温度TCR，推导。除了AKARI数据，我们还模拟了IRTF/SpeX和UKIRT/CGS 4光谱，以获得最可能的物理参数。的光谱类型和建模参数之间的相关性进行检查。我们证实，晚L矮星的光谱型序列是不相关的T eff，而是起源于尘埃的影响。
We investigate variations in the strengths of three molecular bands, CH 4 at 3.3 μm, CO at 4.6 μm, and CO 2 at 4.2 μm, in 16 brown dwarf spectra obtained by AKARI. Spectral features are examined along the sequence of source classes from L1 to T8. We find that the CH 4 3.3 μm band is present in the spectra of brown dwarfs later than L5, and the CO 4.6 μm band appears in all spectral types. The CO 2 absorption band at 4.2 μm is detected in late-L and T-type dwarfs. To better understand brown dwarf atmospheres, we analyze the observed spectra using the Unified Cloudy Model. The physical parameters of the AKARI sample, ie, atmospheric effective temperature T eff, surface gravity log g, and critical temperature T cr, are derived. We also model IRTF/SpeX and UKIRT/CGS4 spectra in addition to the AKARI data in order to derive the most probable physical parameters. Correlations between the spectral type and the modeled parameters are examined. We confirm that the spectral-type sequence of late-L dwarfs is not related to T eff, but instead originates as a result of the effect of dust.