Cloud busting: enstatite and quartz clouds in the atmosphere of 2M2224-0158

Abstract

We present the most detailed data-driven exploration of cloud opacity in a substellar object to-date. We have tested over 60 combinations of cloud composition and structure, particle size distribution, scattering model, and gas phase composition assumptions against archival $1-15\mu \mathrm{m}$ spectroscopy for the unusually red L4.5~dwarf 2MASSW~J2224438-015852 using the Brewster retrieval framework. We find that, within our framework, a model that includes enstatite and quartz cloud layers at shallow pressures, combined with a deep iron cloud deck fits the data best. This models assumes a Hansen distribution for particle sizes for each cloud, and Mie scattering. We retrieved particle effective radii of ${\log }_{10}a(\mu \mathrm{m})=-1.41_{-0.17}^{+0.18}$ for enstatite, $-0.44_{-0.20}^{+0.04}$ for quartz, and $-0.77_{-0.06}^{+0.05}$ for iron. Our inferred cloud column densities suggest $(Mg/Si)=0.69_{-0.08}^{+0.06}$ if there are no other sinks for magnesium or silicon. Models that include forsterite alongside, or in place of, these cloud species are strongly rejected in favour of the above combination. We estimate a radius of $0.75\pm 0.02$ Rjup, which is considerably smaller than predicted by evolutionary models for a field age object with the luminosity of 2M2224-0158. Models which assume vertically constant gas fractions are consistently preferred over models that assume thermochemical equilibrium. From our retrieved gas fractions we infer $[M/H]=+0.38_{-0.06}^{+0.07}$ and $C/O=0.83_{-0.07}^{+0.06}$. Both these values are towards the upper end of the stellar distribution in the Solar neighbourhood, and are mutually consistent in this context. A composition toward the extremes of the local distribution is consistent with this target being an outlier in the ultracool dwarf population.

20 pages, 10 figures, MNRAS accepted

References in corpus (25)

• Array Programming with NumPy
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• The 0.8-14.5 micron Spectra of Mid-L to Mid-T Dwarfs: Diagnostics of Effective Temperature, Grain Sedimentation, Gas Transport, and Surface Gravity
• Fingering convection and cloudless models for cool brown dwarf atmospheres
• The Hawaii Infrared Parallax Program. II. Young Ultracool Field Dwarfs
• Transmission spectral properties of clouds for hot Jupiter exoplanets
• Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e
• The Field Substellar Mass Function Based on the Full-sky 20-pc Census of 525 L, T, and Y Dwarfs
• Consistent simulations of substellar atmospheres and non-equilibrium dust-cloud formation
• High temperature condensate clouds in super-hot Jupiter atmospheres
• Peering into the formation history of beta Pictoris b with VLTI/GRAVITY long baseline interferometry
• Carbon and oxygen abundances in stellar populations
• Physical parameters of two very cool T dwarfs
• Helios-r2 -- A new Bayesian, open-source retrieval model for brown dwarfs and exoplanet atmospheres
• Atmospheres of Brown Dwarfs
• Model Atmospheres From Very Low Mass Stars to Brown Dwarfs
• On the Radii of Brown Dwarfs Measured with AKARI Near-Infrared Spectroscopy
• Exploring the Role of Sub-micron Sized Dust Grains in the Atmospheres of Red L0 - L6 Dwarfs
• A Search for Photometric Variability in L and T type Brown Dwarf Atmospheres
• Retrieval of SDSS J1416+1348AB
• Host-star and exoplanet compositions: a pilot study usinga wide binary with a polluted white dwarf
• High-resolution Spectroscopic Study of Dwarf Stars in the Northern Sky: Lithium, Carbon, and Oxygen Abundances
• Rotation periods and photometric variability of rapidly rotating ultra-cool dwarfs
• Large-scale changes of the cloud coverage in the $\epsilon$ Indi Ba,Bb system

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