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Astrophysics and Astronomy

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L dwarfs

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Full-Text Articles in Physical Sciences and Mathematics

A Comparative L-Dwarf Sample Exploring The Interplay Between Atmospheric Assumptions And Data Properties, Eileen C. Gonzales, Ben Burningham, Jacqueline K. Faherty, Nikole K. Lewis, Channon Visscher, Mark Marley Oct 2022

A Comparative L-Dwarf Sample Exploring The Interplay Between Atmospheric Assumptions And Data Properties, Eileen C. Gonzales, Ben Burningham, Jacqueline K. Faherty, Nikole K. Lewis, Channon Visscher, Mark Marley

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Comparisons of atmospheric retrievals can reveal powerful insights on the strengths and limitations of our data and modeling tools. In this paper, we examine a sample of five L dwarfs of similar effective temperature (Teff) or spectral type to compare their pressure–temperature (P-T) profiles. Additionally, we explore the impact of an object's metallicity and the signal-to-noise ratio (S/N) of the observations on the parameters we can retrieve. We present the first atmospheric retrievals: 2MASS J15261405+2043414, 2MASS J05395200−0059019, 2MASS J15394189−0520428, and GD 165B increasing the small but growing number of L dwarfs retrieved. When compared to the atmospheric retrievals …


Following The Lithium: Tracing Li-Bearing Molecules Across Age, Mass, And Gravity In Brown Dwarfs, Ehsan Gharib-Nezhad, Mark S. Marley, Natasha E. Batalha, Channon Visscher, Richard S. Freedman, Roxana E. Lupu Sep 2021

Following The Lithium: Tracing Li-Bearing Molecules Across Age, Mass, And Gravity In Brown Dwarfs, Ehsan Gharib-Nezhad, Mark S. Marley, Natasha E. Batalha, Channon Visscher, Richard S. Freedman, Roxana E. Lupu

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Lithium is an important element for the understanding of ultracool dwarfs because it is lost to fusion at masses above ∼68 MJ. Hence, the presence of atomic Li has served as an indicator of the nearby H-burning boundary at about 75 MJ between brown dwarfs and very low mass stars. Historically, the “lithium test,” a search for the presence of the Li line at 670.8 nm, has been a marker if an object has a substellar mass. While the Li test could, in principle, be used to distinguish masses of later-type L–T dwarfs, Li is predominantly no longer found as …