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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.; [...]

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

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  • Medientyp: E-Artikel
  • Titel: A Clear View of a Cloudy Brown Dwarf Companion from High-resolution Spectroscopy
  • 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.; [...]
  • Erschienen: American Astronomical Society, 2022
  • Erschienen in: The Astrophysical Journal
  • Sprache: Nicht zu entscheiden
  • DOI: 10.3847/1538-4357/ac8673
  • ISSN: 0004-637X; 1538-4357
  • Schlagwörter: Space and Planetary Science ; Astronomy and Astrophysics
  • Entstehung:
  • Anmerkungen:
  • Beschreibung: <jats:title>Abstract</jats:title> <jats:p>Direct imaging studies have mainly used low-resolution spectroscopy (<jats:italic>R</jats:italic> ∼ 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 (<jats:italic>R</jats:italic> ∼ 35,000 in the <jats:italic>K</jats:italic> band), and aims to address these challenges with high-resolution spectroscopy. Using an atmospheric retrieval framework based on <jats:monospace>petitRADTRANS</jats:monospace>, we analyze the KPIC high-resolution spectrum (2.29–2.49 <jats:italic>μ</jats:italic>m) and the archival low-resolution spectrum (1–2.2 <jats:italic>μ</jats:italic>m) of the benchmark brown dwarf HD 4747 B (<jats:italic>m</jats:italic> = 67.2 ± 1.8 <jats:italic>M</jats:italic> <jats:sub>Jup</jats:sub>, <jats:italic>a</jats:italic> = 10.0 ± 0.2 au, <jats:italic>T</jats:italic> <jats:sub>eff</jats:sub> ≈ 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<jats:italic>σ</jats:italic>–2<jats:italic>σ</jats:italic>. The retrieved parameters from the <jats:italic>K</jats:italic>-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<jats:sub>2</jats:sub>O, and CH<jats:sub>4</jats:sub> (volume-mixing ratio of log(CH<jats:sub>4</jats:sub>) = −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.</jats:p>
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