Neptune high-latitude emission: Dependence of angle on frequency

• Main Author: Sawyer, Constance
• Format: Other/Unknown Material
• Language: unknown
• Published: 1993
• Subjects: SPACE RADIATION; North Magnetic Pole
• Online Access: http://hdl.handle.net/2060/19940009003

Smooth broadband radio emission reached a maximum and then cut off as Voyager approached the north magnetic pole of Neptune. The time of each event depends on frequency, yielding information on radio source location, and emission angle. In a preliminary analysis L-shell and magnetic longitude define radio-source locations in a dipole field. The emission angle at each frequency is identified with the angle between the magnetic-field direction at the source and the line of sight to Voyager 2 at the time of emission maximum. At each value of L in the range 6 less than L less than 9, there is one source longitude for which emission angle varies smoothly from greater or equal to 90 deg at 40 kHz to as low as 20 deg at 462 kHz. A more complex magnetic-field model can give a qualitatively different result.