Solar Implications of ULYSSES Interplanetary Field Measurements
Abstract
Recent observations by the Ulysses magnetometer team have shown that the strength of the radial interplanetary field component, |Br| , is essentially independent of latitude, a result which implies that the heliospheric currents are confined entirely to thin sheets. Using such a current sheet model, we extrapolate the observed photospheric field to 1 AU and compare the predicted magnitude and sign of Br with spacecraft measurements during 1970--1993. Approximate agreement can be obtained if the solar magnetograph measurements in the Fe I lambda 5250 line are scaled upward by a latitude-dependent factor, similar to that derived by Ulrich from a study of magnetic saturation effects. The correction factor implies sharply peaked polar fields near sunspot minimum, with each polar coronal hole having a mean field strength of 10 G.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1995
- DOI:
- 10.1086/309578
- Bibcode:
- 1995ApJ...447L.143W
- Keywords:
-
- INTERPLANETARY MEDIUM;
- SUN: CORONA;
- SUN: MAGNETIC FIELDS;
- SUN: SOLAR WIND