Measurements of brightness and nonradial direction of coronal streamers according to data of SOHO/Large Angle and Spectrometric Coronagraph Experiment (LASCO)-C2
Gun-Der Kim,
V. I. Makarov,
and A. G. Tlatov
Kislovodsk Solar Station of the Pulkovo Observatory, St. Petersburg, Russia
Abstract
[1] Daily observations of the corona were processed according to the data of coronagraph SOHO/Large Angle and Spectrometric Coronagraph Experiment (LASCO)-C2 to study the variations of brightness and nonradial direction of coronal streamers during 1996.5-2003.5. Photometry of coronal images was carried out at heights of 2.3 R
-5.5 R with
a step of
2o along position angle. The total number of
processed days has been about 4300. The latitude-time
distributions of coronal intensity were analyzed at different
heights. The maximum brightness of the corona was
observed in the equatorial zone in the solar minimum. The
drifts of coronal intensity were observed in direction to the
poles in the beginning of solar cycle. The maximum
brightness of high-latitude corona was observed during the
polar magnetic field reversal of the Sun in 1999-2001. The
drifts of low coronal brightness were observed in the opposite
direction from high latitudes to the equator after polar
magnetic field reversal. The angles of deviation from radial
direction of coronal streamers were determined on daily
coronal images. It was found that coronal streamers were
inclined on the whole to the equator during 1996.5-1999.5,
although after 1999.5 the streamers were inclined to the
poles. The angles of nonradial direction of the streamers
reached about 10o-15o. The longitudinal distribution of
coronal brightness at various heights was considered. It was
compared with heliosphere neutral layer and with drift of
filament bands in an epoch of polar magnetic field reversal of
the Sun.
Received 9 April 2004; revised 7 October 2004; accepted 17 November 2004; published 28 December 2004.
Keywords: Solar corona; coronal rays; coronal observations.
Index Terms: 7509 Solar Physics, Astrophysics, and Astronomy: Corona; 7524 Solar Physics, Astrophysics, and Astronomy: Magnetic fields; 7536 Solar Physics, Astrophysics, and Astronomy: Solar activity cycle.
Citation: (2004), Measurements of brightness and nonradial direction of coronal streamers according to data of SOHO/Large Angle and Spectrometric Coronagraph Experiment (LASCO)-C2, Int. J. Geomagn. Aeron., 5, GI2011, doi:10.1029/2004GI000069.
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