L-band spectroscopy of young brown dwarfs

被引:2
作者
Beiler, Samuel A. [1 ,2 ]
Allers, Katelyn N. [2 ]
Cushing, Michael [1 ]
Faherty, Jacqueline [3 ]
Marley, Mark [4 ]
Skemer, Andrew [5 ]
机构
[1] Univ Toledo, Ritter Astrophys Res Ctr, Dept Phys & Astron, 2801 W Bancroft St, Toledo, OH 43606 USA
[2] Bucknell Univ, Dept Phys & Astron, Lewisburg, PA 17837 USA
[3] Amer Museum Nat Hist, Dept Astrophys, Cent Pk West 79th St, New York, NY 10024 USA
[4] Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA
[5] Univ Calif Santa Cruz, Dept Astron & Astrophys, Santa Cruz, CA 95064 USA
基金
美国国家科学基金会;
关键词
planets and satellites; atmospheres; -; stars; atmosphere - brown dwarfs - stars; low-mass; LOW-MASS STARS; ABSOLUTE CALIBRATION; T-DWARF; DISCOVERY; MODEL; RED;
D O I
10.1093/mnras/stac3307
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present a L-band (2.98-3.96 mu m) spectroscopic study of eight young L dwarfs with spectral types ranging from L2 to L7. Our spectra (lambda/delta lambda asymptotic to 250-600) were collected using the Gemini near-infrared spectrograph. We first examine the young L-band spectral sequence, most notably analysing the evolution of the Q-branch of methane absorption feature at 3.3 mu m. We find the Q-branch feature first appears between L3 and L6, as previously seen in older field dwarfs. Secondly, we analyse how well various atmospheric models reproduce the L band and published near-IR (0.7-2.5 mu m) spectra of our objects by fitting five different grids of model spectra to the data. Best-fit parameters for the combined near-IR and L-band data are compared to best-fit parameters for just the near-IR data, isolating the impact that the addition of the L band has on the results. This addition notably causes a -100 K drop in the best-fit ef fecti ve temperature. Also, when clouds and a vertical mixing rate (K-zz) are included in the models, thick clouds, and higher K-zz values are preferred. Five of our objects also have previously published effective temperatures and surface gravities derived using evolutionary models, age estimates, and bolometric luminosities. Comparing model spectra matching these parameters to our spectra, we find disequilibrium chemistry and clouds are needed to match these published ef fecti ve temperatures. Three of these objects are members of AB Dor, allowing us to show the temperature dependence of the Q-branch of methane.
引用
收藏
页码:4870 / 4894
页数:25
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