Issue |
A&A
Volume 522, November 2010
|
|
---|---|---|
Article Number | A27 | |
Number of page(s) | 5 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361/201014082 | |
Published online | 28 October 2010 |
The centenary variations in the solar corona shape in accordance with the observations during the minimal activity epoch
Kislovodsk Mountain Station, The Central Astronomical Observatory of RAS at
Pulkovo,
357700
Kislovodsk,
Russia
e-mail: tlatov@mail.ru
Received:
16
January
2010
Accepted:
2
June
2010
Aims. We investigate the long-term change in coronal large-scale structure at periods of minimum solar activity from 1878 to 2008.
Methods. A parameter γ that characterizes the angle between high-latitude boundaries of the large coronal streamers at a distance of 2 R⊙ is used to quantify the large-scale coronal structure at minimum solar activity. The comparative analysis of the solar corona during the minimum epochs in activity cycles 12 to 24 shows that the index has been slow and steadily changing during the past 130 years.
Results. The maximum value of the index occurred during activity cycles 17 to 19, i.e. around 1950, which was the period when the global magnetic field of the Sun was closest to a dipole configuration. During activity minima close to the years 1900 and 2000, the large-scale coronal structure corresponded to a quadrupole configuration. The reasons for the variations in the solar coronal structure and its relation with long-term variations in the geomagnetic indices and Gleissberg cycle are discussed.
Key words: Sun: corona / Sun: activity / Sun: heliosphere / Sun: magnetic topology
© ESO, 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.