EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Ng & Beard 1979
Ng, K.H. and Beard, D.B. (1979). Possible displacement of mercury’s dipole. Journal of Geophysical Research 84: doi: 10.1029/JA084iA05p02115. issn: 0148-0227.

Earlier attempts to model the Hermean magnetospheric field based on a planet-centered magnetic multipole field have required the addition of a quadrupole moment to obtain a good fit to space vehicle observations. In this work we obtain an equally satisfactory fit by assuming a null quadrupole moment and least squares fitting of the displacement of the planetary dipole from the center of the planet. We find a best fit for a dipole displacement from the planet center of 0.033 Rm away from the solar direction, 0.025 Rm toward dawn in the magnetic equatorial plane, and 0.189 Rm northward along the magnetic dipole axis, where Rm is the planet radius. Therefore the presence of a magnetic quadrupole moment is not ruled out. The compressed dipole field more completely represents the field in the present work than in previous work where the intrinsic quadrupole field was not included in the magnetopause surface and field calculations. Moreover, we have corrected a programing error in previous work in the computation of dipole tilt &lgr; away from the sun. We find a slight increase for the planet dipole moment of 190&ggr;Rm3 and a dipole tilt angle &lgr; away from the sun. We find a slight increase for the planet moment of 190&ggr;Rm3 and a dipole tilt angle &lgr; of only 1.2¿ away from the sun. All other parameters are essentially unchanged.

BACKGROUND DATA FILES

Abstract

Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit