Bruce Fegley

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We use thermochemical equilibrium and kinetic calculations to model sulfur and phosphorus chemistry in the atmospheres of giant planets, brown dwarfs, low-mass stars, and extrasolar giant planets (EGPs). The chemical behavior of individual Sand P-bearing gases and condensates is determined as a function of pressure, temperature, and metallicity. Our results(More)
We present new, high resolution, infrared spectra of the T dwarf Gliese 229B in the J, H, and K bandpasses. We analyze each of these as well as previously published spectra to determine its metallicity and the abundances of NH 3 and CO in terms of the surface gravity of Gl 229B, which remains poorly constrained. The metallicity increases with increasing(More)
Sulfurization of meteoritic metal in H2S-H2 gas produced three different sulfides: monosulfide solid solution [(Fe,Ni)1-xS], pentlandite [(Fe,Ni)9-xS8], and a phosphorus-rich sulfide. The composition of the remnant metal was unchanged. These results are contrary to theoretical predictions that sulfide formation in the solar nebula produced troilite (FeS)(More)
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. ABSTRACT It is now understood that the accretion of terrestrial planets(More)
Thermochemical equilibrium calculations of gas abundances and condensation cloud formation are used to model the atmospheric chemistry of Gliese 229B. The calculations , which are analogous to our prior modeling of atmospheric chemistry of the Jo-vian planets in our solar system, predict the abundances of gases which are potentially observable by(More)
Intense bombardment of the moon and terrestrial planets approximately 3.9-4.0 x 10(9) years ago could have caused the chemical reprocessing of the Earth's primitive atmosphere. In particular, the shock heating and rapid quenching caused by the impact of large bodies into the atmosphere could produce molecules such as HCN and H2CO4 which are important(More)
Introduction: The recent observation of NaCl (gas) on Io [1] confirms our earlier prediction that NaCl is produced volcanically [2]. Here we extend our calculations by modeling thermochemical equilibrium I as a function of temperature and pressure in a Pele-like volcanic CI chondritic ratios of the other (as yet unobserved) alkalis and halogens. For(More)