Abstract
view Abstract Citations (23) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Periodic variations in Io's sodium and potassium clouds. Trafton, L. Abstract Spectra of Io's sodium cloud taken 7.5 to 45 sec north and south of Io at a variety of magnetic latitudes of Io obtained during 17 nights of the 1975 apparition of Jupiter confirm the weakening of the cloud in the neighborhood of Jupiter's magnetic equator. The time scale for these changes is 1.5 hours or less. For impact ionization to cause these changes, a minimum flux of 100 billion/sq cm/sec 15 eV electrons or 40 billion/sq cm/sec 8 keV protons is required. Sodium velocities near 10 km/sec are required to explain the replenishment of ionized regions of the cloud. We also obtained spectra of Io's potassium cloud on eight nights during the 1975 apparition. This cloud appears to behave like the sodium cloud as Io's magnetic latitude varies. The potassium, however, may become much weaker as Io passes through the magnetic equator. The brightest intensity measured for the 7665 A resonance line was about 1 kR at a point 7.5 sec east of Io. Publication: The Astrophysical Journal Pub Date: August 1977 DOI: 10.1086/155432 Bibcode: 1977ApJ...215..960T Keywords: Astronomical Spectroscopy; Io; Periodic Variations; Planetary Magnetic Fields; Potassium; Sodium Vapor; Abundance; Clouds; Emission Spectra; Fraunhofer Lines; Ionizing Radiation; Magnetic Equator; Lunar and Planetary Exploration full text sources ADS |
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