| Autor: |
Spencer A. Hurt, Michael C. Liu, Zhoujian Zhang, Mark Phillips, Katelyn N. Allers, Niall R. Deacon, Kimberly M. Aller, William M. J. Best |
| Jazyk: |
angličtina |
| Rok vydání: |
2024 |
| Předmět: |
|
| Zdroj: |
The Astrophysical Journal, Vol 961, Iss 1, p 121 (2024) |
| Druh dokumentu: |
article |
| ISSN: |
1538-4357 |
| DOI: |
10.3847/1538-4357/ad0b12 |
| Popis: |
We present a uniform forward-modeling analysis of 90 late-M and L dwarfs in nearby young (∼10–200 Myr) moving groups, the Pleiades, and the Hyades using low-resolution ( R ≈ 150) near-infrared (0.9–2.4 μ m) spectra and the BT-Settl model atmospheres. We derive the objects’ effective temperatures, surface gravities, radii, and masses by comparing our spectra to the models using a Bayesian framework with nested sampling and calculate the same parameters using evolutionary models. Assuming the evolutionary-based parameters are more robust, our spectroscopically inferred parameters from BT-Settl exhibit two types of systematic behavior for objects near the M-L spectral type boundary. Several objects are clustered around T _eff ≈ 1800 K and $\mathrm{log}g\approx 5.5$ dex, implying impossibly large masses (150–1400 M _Jup ), while others are clustered around T _eff ≳ 3000 K and $\mathrm{log}g\lesssim 3.0$ dex, implying unphysically low masses and unreasonably young ages. We find the fitted BT-Settl model spectra tend to overpredict the peak J - and H -band flux for objects located near the M-L boundary, suggesting the dust content included in the model atmospheres is insufficient to match the observations. By adding an interstellar medium–like reddening law to the BT-Settl model spectra, we find the fits between models and observed spectra are greatly improved, with the largest reddening coefficients occurring at the M-L transition. This work delivers a systematic examination of the BT-Settl model atmospheres and constitutes the largest spectral analysis of benchmark late-M- and L-type brown dwarfs to date. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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