L-band spectroscopy of young brown dwarfs

Author:

Beiler Samuel A1234ORCID,Allers Katelyn N34,Cushing Michael12,Faherty Jacqueline56,Marley Mark78,Skemer Andrew910

Affiliation:

1. Ritter Astrophysical Research Center, Department of Physics & Astronomy , , 2801 W. Bancroft Street, Toledo, OH 43606 , USA

2. University of Toledo , , 2801 W. Bancroft Street, Toledo, OH 43606 , USA

3. Department of Physics & Astronomy , , Lewisburg, PA 17837 , USA

4. Bucknell University , , Lewisburg, PA 17837 , USA

5. Department of Astrophysics , , Central Park West at 79th Street, NY 10024 , USA

6. American Museum of Natural History , , Central Park West at 79th Street, NY 10024 , USA

7. Lunar & Planetary Laboratory , , Tucson, AZ 85721 , USA

8. University of Arizona , , Tucson, AZ 85721 , USA

9. Department of Astronomy & Astrophysics , , Santa Cruz, CA 95064 , USA

10. University of California , , Santa Cruz, CA 95064 , USA

Abstract

ABSTRACT 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 (λ/Δλ ≈ 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 Lband 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 effective temperature. Also, when clouds and a vertical mixing rate (Kzz) are included in the models, thick clouds, and higher Kzz 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 effective temperatures. Three of these objects are members of AB Dor, allowing us to show the temperature dependence of the Q-branch of methane.

Funder

National Science Foundation

National Research Council

Comisión Nacional de Investigación Científica y Tecnológica

Ministerio de Ciencia, Tecnología e Innovación Productiva

Ministério da Ciência, Tecnologia e Inovação

Bucknell University

University of Toledo

University of California, Santa Cruz

Heising-Simons Foundation

Publisher

Oxford University Press (OUP)

Subject

Space and Planetary Science,Astronomy and Astrophysics

Cited by 1 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. JWST/NIRSpec Observations of the Planetary Mass Companion TWA 27B*;The Astrophysical Journal Letters;2023-06-01

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