Large-Scale Polar Coronal Magnetic Field Model and the Expected August 11, 1999 Eclipse Corona
Abstract
We compare available SOHO/LASCO C2 images with the model calculations of the large-scale coronal magnetic field near the magnetic poles of the Sun. The model field consists of the ones of the dipole and of the thin current sheet in the plane perpendicular to the dipole. The positions of the dipole and the current sheet (representing the heliospheric current sheet) are obtained via comparison of the SOHO/LASCO, SOHO/EIT observations and coronal magnetic field calculations (Wilcox Solar Observatory). The values of the solar dipole vector components are taken from the same calculations of the coronal magnetic field. The strength of the heliospheric current sheet is obtained via analyses of the interplanetary magnetic field preliminary data from the ACE spacecraft. This model is better applicable during the solar cycle minimum. However, the obtained model polar magnetic field is in agreement with the observations near the solar maximum, when the polar plumes could be visible over the magnetic (and not heliographic) poles of the Sun if the magnetic dipole is perpendicular to the line of sight. The configuration of the solar corona during the August 11, 1999 total solar eclipse expected from our analysis does not contain polar plumes and will be close to the maximal-shape corona dominated by coronal rays and streamers.
- Publication:
-
Romanian Astronomical Journal
- Pub Date:
- 1999
- Bibcode:
- 1999RoAJ....9S..29V
- Keywords:
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- CORONA;
- MAGNETIC FIELDS;
- HELIOSPHERIC CURRENT SHEET;
- PLUMES;
- STREAMERS