Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets

By R. Freedman, M. Marley, K. Lodders. 2007

407 citations recorded by the source corpus.

Opacities and chemical abundance data are crucial ingredients of ultracool dwarf and extrasolar giant planet atmosphere models. We report here on the detailed sources of molecular opacity data employed by our group for this application. We also present tables of Rosseland and Planck mean opacities, which are of use in some studies of the atmospheres, interiors, and evolution of planets and brown dwarfs. For the tables presented here we have included the opacities of important atomic and molecular species, including the alkali elements, pressure-induced absorption by hydrogen, and other significant opacity sources, but we neglect opacity from condensates. We report for each species how we have assembled molecular line data from a combination of public databases, laboratory data that is not yet in the public databases, and our own numerical calculations. We combine these opacities with abundances computed from a chemical equilibrium model using recently revised solar abundances to compute mean opacities. The chemical equilibrium calculation accounts for the settling of condensates in a gravitational field and is applicable to ultracool dwarf and extrasolar planetary atmospheres, but not circumstellar disks. We find that the inclusion of alkali atomic opacity substantially increases the mean opacities over those currently in the literature at densities relevant to the atmospheres and interiors of giant planets and brown dwarfs. We provide our opacity tables for public use and discuss their limitations.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/8106bac29cc44a683456e33355605b8c2b31fffa

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In Astronomy and Astrophysics

1. Jon Fortney
2. N. Madhusudhan
3. M. Marley
4. A. Showman
5. C. Mordasini
6. V. Parmentier
7. D. Sing
8. Sara Seager

In Instrumentation

1. Jon Fortney
2. N. Madhusudhan
3. M. Marley
4. A. Showman
5. A. Burgasser
6. V. Parmentier
7. M. Line
8. D. Sing

Citations in the corpus

• Formation of Jupiter using opacities based on detailed grain physics (2010, methodology): “Other more detailed calculations of the core accretion rate (Kokubo and Ida, 2000) show in general that the rates calculated by Greenzweig and Lissauer (1992) should be reduced because they do not completely take into account the stirring and increase in relative velocity v of the planetesimals as…”
• EXOPLANET ALBEDO SPECTRA AND COLORS AS A FUNCTION OF PLANET PHASE, SEPARATION, AND METALLICITY (2010, methodology): “The extensive opacity database we use is fully described in Freedman et al. (2008).”
• 3D mixing in hot Jupiters atmospheres. I. Application to the day/night cold trap in HD 209458b (2013, methodology): “We use the opacities developed by Freedman et al. (2008), including more recent updates, and the molecular abundances described by Lodders & Fegley (2002) and Visscher et al. (2006).”
• A TEMPERATURE AND ABUNDANCE RETRIEVAL METHOD FOR EXOPLANET ATMOSPHERES (2009, methodology): “Our H2O, CH4, CO and NH3 molecular line data are from Freedman et al. 2008, and references therein.”
• YOUNG L DWARFS IDENTIFIED IN THE FIELD: A PRELIMINARY LOW-GRAVITY, OPTICAL SPECTRAL SEQUENCE FROM L0 TO L5 (2008, background): “…apparent pressure effects (e.g., sharp K I lines) could be explained by reduced photospheric pressure in a high-metallicity environment instead of low gravity: P ∝ g/κ, where P is pressure, g is gravity, and κ is the mean opacity which is roughly proportional to metallicity (Freedman et al. 2008).”
• THE IMPRINT OF EXOPLANET FORMATION HISTORY ON OBSERVABLE PRESENT-DAY SPECTRA OF HOT JUPITERS (2016, methodology): “For the optical depth calculations we use Rosseland mean opacities from the Freedman et al. (2008) tables for solar and scaled solar abundances, depending on the actual enrichment Z of the planetary envelope.”
• MID-INFRARED PHOTOMETRY OF COLD BROWN DWARFS: DIVERSITY IN AGE, MASS, AND METALLICITY (2010, background): “The atmospheric models include all the significant sources of gas opacity (Freedman et al. 2008).”
• MODULES FOR EXPERIMENTS IN STELLAR ASTROPHYSICS (MESA): PLANETS, OSCILLATIONS, ROTATION, AND MASSIVE STARS (2013, methodology): “Currently, the Ferguson et al. (2005) and Freedman et al. (2008) tables, which include the opacity from molecules, but ignore condensates, are available.”
• Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST (2017, methodology): “The opacity database is based on Freedman et al. (2008) with updates described in Freedman et al. (2014), including methane (Yurchenko & Tennyson 2014) and carbon dioxide (Huang et al. 2013, 2014).”
• KEPLER PLANETS: A TALE OF EVAPORATION (2013, methodology): “The opacity tables are used for the irradiation of the atmosphere are based on an updated verision of the Freedman et al. (2008), as detailed in Paxton et al. (2013), where we adopt an opacity κ∗ = 4 × 10−3 cm2 g−1 to the incoming stellar irradiation suitable for a solar type star (Guillot 2010).”
• Characterization of exoplanets from their formation - I. Models of combined planet formation and evolution (2012, background): “…is given by ∇(T, P) = d ln T d ln P = min(∇ad,∇rad), (3) where the radiative gradient (in radiative zones) in the diffusion approximation is given as ∇rad = 364πσG κlP T 4m , (4) where κ denotes the opacity (given by Bell & Lin 1994; and Freedman et al. 2008) and σ is the Stefan-Boltzmann constant.”
• DISEQUILIBRIUM CARBON, OXYGEN, AND NITROGEN CHEMISTRY IN THE ATMOSPHERES OF HD 189733b AND HD 209458b (2011, methodology): “Absorption by CO2 is calculated from the HITRAN hot CO2 line list (Tashkun et al. 2003), as is that of CO and NH3 (Rothman et al. 2009), and the methane line parameters derive from the hot CH4 line parameters of Freedman et al. (2008).”
• HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering (2014, background): “Chemical mixing ratios and opacities assume solar metallicity and local thermo-chemical equilibrium accounting for condensation and thermal ionisation but no photoionisation (Lodders 1999; Lodders & Fegley 2002; Freedman et al. 2008).”
• PLANETARY POPULATION SYNTHESIS COUPLED WITH ATMOSPHERIC ESCAPE: A STATISTICAL VIEW OF EVAPORATION (2014, methodology): “In contrast, the atmospheric opacity during planetary evolution is identical for all three populations and is given via the opacity of a grain-free gas with a solar composition (Freedman et al. 2008).”
• THE 0.8–14.5 μm SPECTRA OF MID-L TO MID-T DWARFS: DIAGNOSTICS OF EFFECTIVE TEMPERATURE, GRAIN SEDIMENTATION, GAS TRANSPORT, AND SURFACE GRAVITY (2009, methodology): “We calculate opacities and generate line profiles in the manner described by Freedman et al. (2008).”
• THREE POSSIBLE ORIGINS FOR THE GAS LAYER ON GJ 1214b (2009, methodology): “For the opacity in the water vapor layer we use Planck means calculated with molecular line data from Freedman et al. (2008).”
• A FRAMEWORK FOR CHARACTERIZING THE ATMOSPHERES OF LOW-MASS LOW-DENSITY TRANSITING PLANETS (2013, methodology): “Thus the formation and evolution of the planets is in fact the one of planets with all solids in the (computational) core and a pure H/He envelope which is modeled with the EOS of Saumon et al. (1995), and the solar composition opacities of Bell et al. (1997) and Freedman et al. (2008).”
• THE NIRSPEC ULTRACOOL DWARF RADIAL VELOCITY SURVEY (2010, methodology): “The models used here have solar metallicity (Lodders 2003), use the opacities described in Freedman et al. (2008), have a fixed gravity of log g = 5 (cgs), and cover a range of Teff from 1200 to 2400 K.”