First observations of CO and HCN on Neptune and Uranus at millimeter wavelengths and the implications for atmospheric chemistry

Abstract

view Abstract Citations (101) References (59) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS First Observations of CO and HCN on Neptune and Uranus at Millimeter Wavelengths and Their Implications for Atmospheric Chemistry Marten, A. ; Gautier, D. ; Owen, T. ; Sanders, D. B. ; Matthews, H. E. ; Atreya, S. K. ; Tilanus, R. P. J. ; Deane, J. R. Abstract Observations are presented which show that CO is present in both the troposphere and stratosphere of Neptune, whereas is confined to the Neptune stratosphere with a mean mole fraction in the 0.003-30 mbar pressure level range of 1.0 x 10 exp -9. CO is present in both the stratosphere and in the troposphere with a uniformly mixed model fraction of 1.2 x 10 exp -6. Upper limits of 1.0 x 10 exp -10 and 3.0 x 10 exp -8 mole fractions are derived for HCN and CO respectively on Uranus. The origin of these species in the atmosphere of Neptune and their nondetection in that of Uranus are discussed in detail. It is concluded that the most plausible scenario involves upward convection of CO and N2 from Neptune's deep interior and a failure of chemical equilibrium at deep atmospheric levels, allowing excess CO and presumably N2 to reach the upper atmosphere. Nondetection in Uranus may be explained by the lack of a significant internal heat source in the planet and consequent suppression of vertical convection. Publication: The Astrophysical Journal Pub Date: March 1993 DOI: 10.1086/172440 Bibcode: 1993ApJ...406..285M Keywords: Atmospheric Chemistry; Carbon Monoxide; Hydrocyanic Acid; Neptune Atmosphere; Uranus Atmosphere; Line Spectra; Millimeter Waves; Radio Telescopes; PLANETS; NEPTUNE; URANUS; CARBON MONOXIDE; WAVELENGTHS; ATMSOPHERE; CHEMISTRY; HYDROGEN CYANIDE; EMISSIONS; EARTH-BASED OBSERVATIONS; STRATOSPHERE; TROPOSPHERE; ABUNDANCE; ORIGIN; SOURCE; CONVECTION; NITROGEN; AMMONIA; RADITIVE TRANSFER; OPACITY; TEMPERATURE; SPECTRA; DISTRIBUTION; FREQUENCIES; COMPARISON; MODEL; THERMOCHEMISTRY; TRITON; SATELLITES; Lunar and Planetary Exploration; Planets; Mercury; Uranus; PLANETS AND SATELLITES: INDIVIDUAL NEPTUNE; PLANETS AND SATELLITES: INDIVIDUAL URANUS full text sources ADS |