Details

Autor(en) / Beteiligte

• Xuan, Jerry W.
• Wang, Jason
• Ruffio, Jean-Baptiste
• Knutson, Heather
• Mawet, Dimitri
• Mollière, Paul
• Kolecki, Jared
• Vigan, Arthur
• Mukherjee, Sagnick
• Wallack, Nicole
• Wang, Ji
• Baker, Ashley
• Bartos, Randall
• Blake, Geoffrey A.
• Bond, Charlotte Z.
• Bryan, Marta
• Calvin, Benjamin
• Cetre, Sylvain
• Chun, Mark
• Delorme, Jacques-Robert
• Doppmann, Greg
• Echeverri, Daniel
• Finnerty, Luke
• Fitzgerald, Michael P.
• Horstman, Katelyn
• Inglis, Julie
• Jovanovic, Nemanja
• López, Ronald
• Martin, Emily C.
• Morris, Evan
• Pezzato, Jacklyn
• Ragland, Sam
• Ren, Bin
• Ruane, Garreth
• Sappey, Ben
• Schofield, Tobias
• Skemer, Andrew
• Venenciano, Taylor
• Wallace, J. Kent
• Wizinowich, Peter

Titel

A Clear View of a Cloudy Brown Dwarf Companion from High-resolution Spectroscopy

Ist Teil von

• The Astrophysical journal, 2022-10, Vol.937 (2), p.54

Ort / Verlag

Philadelphia: The American Astronomical Society

Erscheinungsjahr

2022

Link zum Volltext

Quelle

EZB Free E-Journals

Beschreibungen/Notizen

• Abstract Direct imaging studies have mainly used low-resolution spectroscopy ( R ∼ 20–100) to study the atmospheres of giant exoplanets and brown dwarf companions, but the presence of clouds has often led to degeneracies in the retrieved atmospheric abundances (e.g., carbon-to-oxygen ratio, metallicity). This precludes clear insights into the formation mechanisms of these companions. The Keck Planet Imager and Characterizer (KPIC) uses adaptive optics and single-mode fibers to transport light into NIRSPEC ( R ∼ 35,000 in the K band), and aims to address these challenges with high-resolution spectroscopy. Using an atmospheric retrieval framework based on petitRADTRANS , we analyze the KPIC high-resolution spectrum (2.29–2.49 μ m) and the archival low-resolution spectrum (1–2.2 μ m) of the benchmark brown dwarf HD 4747 B ( m = 67.2 ± 1.8 M Jup , a = 10.0 ± 0.2 au, T eff ≈ 1400 K). We find that our measured C/O and metallicity for the companion from the KPIC high-resolution spectrum agree with those of its host star within 1 σ –2 σ . The retrieved parameters from the K -band high-resolution spectrum are also independent of our choice of cloud model. In contrast, the retrieved parameters from the low-resolution spectrum are highly sensitive to our chosen cloud model. Finally, we detect CO, H 2 O, and CH 4 (volume-mixing ratio of log(CH 4 ) = −4.82 ± 0.23) in this L/T transition companion with the KPIC data. The relative molecular abundances allow us to constrain the degree of chemical disequilibrium in the atmosphere of HD 4747 B, and infer a vertical diffusion coefficient that is at the upper limit predicted from mixing length theory.