ATMOSPHERIC CHEMISTRY IN GIANT PLANETS, BROWN DWARFS, AND LOW-MASS DWARF STARS. III. IRON, MAGNESIUM, AND SILICON

2010/01/20 by Channon Visscher, K. Lodders, Katharina Lodders +2 · 264 citations
Chemistry · Physics and Astronomy · #Astro and Planetary Science #Astrobiology #Astronomy #Astrophysics #Atmosphere (unit) #Brown dwarf #Chemistry #Exoplanet #Forsterite #Gas giant #Giant planet #Jupiter (rocket family) #Mineralogy #Physics #Planet #Planetary Science and Exploration #Planetary system #Stellar, planetary, and galactic studies #Thermodynamics #astro-ph.EP

paper · pdf · doi:10.1088/0004-637x/716/2/1060

published in The Astrophysical Journal 716(2), 1060-1075 (IOP Publishing) · 42 pages, 15 figures, submitted to the Astrophysical Journal

arxiv created 2010/01/20 · openalex publication_date 2010/05/26 · arxiv updated 2015/05/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06

Abstract

We use thermochemical equilibrium calculations to model iron, magnesium, and silicon chemistry in the atmospheres of giant planets, brown dwarfs, extrasolar giant planets (EGPs), and low-mass stars. The behavior of individual Fe-, Mg-, and Si-bearing gases and condensates is determined as a function of temperature, pressure, and metallicity. Our equilibrium results are thus independent of any particular model atmosphere. The condensation of Fe metal strongly affects iron chemistry by efficiently removing Fe-bearing species from the gas phase. Monatomic Fe is the most abundant Fe-bearing gas throughout the atmospheres of EGPs and L dwarfs, and in the deep atmospheres of giant planets and T dwarfs. Mg- and Si-bearing gases are effectively removed from the atmosphere by forsterite (Mg 2 SiO 4 ) and enstatite (MgSiO 3 ) cloud formation. Monatomic Mg is the dominant magnesium gas throughout the atmospheres of EGPs and L dwarfs and in the deep atmospheres of giant planets and T dwarfs. Silicon monoxide (SiO) is the most abundant Si-bearing gas in the deep atmospheres of brown dwarfs and EGPs, whereas SiH 4 is dominant in the deep atmosphere of Jupiter and other gas giant planets. Several other Fe-, Mg-, and Si-bearing gases become increasingly important with decreasing effective temperature. In principle, a number of Fe, Mg, and Si gases are potential tracers of weather or diagnostic of temperature in substellar atmospheres.

Citations

• Oscillator Strengths and Damping Constants for Atomic Lines in the J and H Bands
• The NIRSPEC Brown Dwarf Spectroscopic Survey. I. Low‐Resolution Near‐Infrared Spectra
• Four Nearby L Dwarfs
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• New Spectral Types L and T
• FeH Absorption in the Near‐Infrared Spectra of Late M and L Dwarfs
• ABUNDANT CIRCUMSTELLAR SILICA DUST AND SiO GAS CREATED BY A GIANT HYPERVELOCITY COLLISION IN THE ∼12 MYR HD172555 SYSTEM

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