NEGLECTED CLOUDS IN T AND Y DWARF ATMOSPHERES

By C. Morley, Jon Fortney, M. Marley, C. Visscher, D. Saumon, S. Leggett. 2012

284 citations recorded by the source corpus.

As brown dwarfs cool, a variety of species condense in their atmospheres, forming clouds. Iron and silicate clouds shape the emergent spectra of L dwarfs, but these clouds dissipate at the L/T transition. A variety of other condensates are expected to form in cooler T dwarf atmospheres. These include Cr, MnS, Na2S, ZnS, and KCl, but the opacity of these optically thinner clouds has not been included in previous atmosphere models. Here, we examine their effect on model T and Y dwarf atmospheres. The cloud structures and opacities are calculated using the Ackerman & Marley cloud model, which is coupled to an atmosphere model to produce atmospheric pressure–temperature profiles in radiative–convective equilibrium. We generate a suite of models between Teff = 400 and 1300 K, log g = 4.0 and 5.5, and condensate sedimentation efficiencies from fsed = 2 to 5. Model spectra are compared to two red T dwarfs, Ross 458C and UGPS 0722–05; models that include clouds are found to match observed spectra significantly better than cloudless models. The emergence of sulfide clouds in cool atmospheres, particularly Na2S, may be a more natural explanation for the “cloudy” spectra of these objects, rather than the reemergence of silicate clouds that wane at the L-to-T transition. We find that sulfide clouds provide a mechanism to match the near- and mid-infrared colors of observed T dwarfs. Our results indicate that including the opacity of condensates in T dwarf atmospheres is necessary to accurately determine the physical characteristics of many of the observed objects.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/6251652304c32ecc0fb7c2cd3f80369d8cb98b36

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

In Statistical and Nonlinear Physics

Citations in the corpus

WEATHER ON OTHER WORLDS. II. SURVEY RESULTS: SPOTS ARE UBIQUITOUS ON L AND T DWARFS (2014, background): “…these include refractory compounds (e.g., oxides, silicates, etc; collectively referred to as “dust”), while at lower temperatures and pressures the condensates consist of more volatile compounds (e.g., alkali salts, water; e.g., Fegley & Lodders 1996; Ackerman & Marley 2001; Morley et al. 2012).”
A T8.5 BROWN DWARF MEMBER OF THE ξ URSAE MAJORIS SYSTEM (2012, methodology): “If something like the Morley et al. (2012) sulfide clouds is not causing the red J −W2 color of WISE 1118+31, then there is a tension between the absolute magnitude MW2, which requires a fairly high Teff , and the colors and spectral type which suggest a lower temperature.”
Transmission spectral properties of clouds for hot Jupiter exoplanets (2014, background): “…dwarf atmospheres suggest that silicates are likely to form the dominant cloud structures in hot Jupiter atmospheres where temperatures are greater than ∼1000 K, with sulphide clouds becoming dominant at temperatures below 900 K at which chlorides also begin to condense out (Morley et al. 2012).”
HST SPECTRAL MAPPING OF L/T TRANSITION BROWN DWARFS REVEALS CLOUD THICKNESS VARIATIONS (2013, background): “Particularly interesting well-studied examples are see in Ross 458C (Burgasser et al. 2010; Burningham et al. 2011; Morley et al. 2012) and 2M1207b Chauvin et al. (2005); Mohanty et al. (2007); Patience et al. (2010); Barman et al. (2011b); Skemer et al. (2011).”
GASEOUS MEAN OPACITIES FOR GIANT PLANET AND ULTRACOOL DWARF ATMOSPHERES OVER A RANGE OF METALLICITIES AND TEMPERATURES (2014, background): “In our recent work on brown dwarf model atmospheres, we have found these new opacity databases provide better fits to observed brown dwarf spectra (Saumon et al. 2012; Morley et al. 2012).”
A STUDY OF THE DIVERSE T DWARF POPULATION REVEALED BY WISE (2013, background): “One promising avenue is the recent work of Morley et al. (2012) to include sulfide clouds in modeling the coolest brown dwarf atmospheres.”
Pale Orange Dots: The Impact of Organic Haze on the Habitability and Detectability of Earthlike Exoplanets (2016, background): “However, ZnS is not a realistic aerosol candidate for Earthlike atmospheres because it condenses at temperatures close to 1000 K (Morley et al. 2012).”
QUANTITATIVELY ASSESSING THE ROLE OF CLOUDS IN THE TRANSMISSION SPECTRUM OF GJ 1214b (2013, methodology): “We use the methods developed and described in Morley et al. (2012) to include the same clouds in a super-Earth atmosphere.”
Discovery and spectroscopy of the young jovian planet 51 Eri b with the Gemini Planet Imager (2015, unknown): “Clouds are important sources of opacity in previously discovered directly imaged planets ( 1) and recent evidence suggests that clouds may play an important role even in low-temperature brown dwarfs previously thought to be completely cloud free ( 88 ).”
On the Cool Side: Modeling the Atmospheres of Brown Dwarfs and Giant Planets (2014, methodology): “…and thermal profile between strict two-stream solutions and general multi-stream solutions, and is the approach currently used in the Marley/Saumon brown dwarf and giant planet models (e.g., Marley et al. 2002; Fortney et al. 2005; Saumon & Marley 2008; Morley et al. 2012; Marley et al. 2012).”
HOW TO DISTINGUISH BETWEEN CLOUDY MINI-NEPTUNES AND WATER/VOLATILE-DOMINATED SUPER-EARTHS (2013, background): “…observations of GJ 1214b. KCl and ZnS are considered for GJ 1214b because the he temperature pressure profile in the atmosphere of GJ 1214b is likely to cross their condensation curves, suggesting that KCl and ZnS may be able condense in the atmosphere of GJ 1214b (Morley et al. 2012, 2013).”
TRANSITIONS IN THE CLOUD COMPOSITION OF HOT JUPITERS (2016, methodology): “We then calculate the lightcurves assuming the same metal enrichment to determine the opacities, the abundances of cloud-forming material and the condensation curves for MnS and MgSiO3 clouds (Morley et al. 2012; Visscher et al. 2010).”
HST PanCET Program: A Cloudy Atmosphere for the Promising JWST Target WASP-101b (2017, methodology): “We approximate the condensate cloud forming species from multiple condensation curves from Visscher et al. (2010), Morley et al. (2012), and Wakeford et al. (2017).”