near-infrared nitric oxide nightglow in the upper atmosphere of Venus

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 106; no. 4; pp. 985 - 988
• Main Authors: García Muñoz, A, Mills, F.P, Piccioni, G, Drossart, P
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 27.01.2009; National Acad Sciences
• Series: From the Cover
• Subjects: Airglow; Altitude; Atmosphere; Emission spectra; Infrared radiation; Mars; Nitric oxide; Oxides; Oxygen; Physical Sciences; Space based observatories; Spectral bands; Upper atmosphere; Venus
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0808091106

The v' = 0 progressions of the C [rightward arrow] X and A [rightward arrow] X band systems of nitric oxide dominate the middle-UV spectrum of the night-time upper atmospheres of the Earth, Mars, and Venus. The C(0) [rightward arrow] A(0)+hν radiative transition at 1.224 μm, the only channel effectively populating the A(0) level, must therefore occur also. There have been, however, no reported detections of the C(0) [rightward arrow] A(0) band in the atmospheres of these or any other planets. We analyzed all available near-infrared limb observations of the dark-side atmosphere of Venus by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument on the Venus Express spacecraft and found 2 unambiguous detections of this band at equatorial latitudes that seem to be associated with episodic events of highly enhanced nightglow emission. The discovery of the C(0) [rightward arrow] A(0) band means observations in the 1.2-1.3 μm region, which also contains the a(0) [rightward arrow] X(0) emission band of molecular oxygen, can provide a wealth of information on the high-altitude chemistry and dynamics of the Venusian atmosphere.