Variation of solar coronal Fe XIV 5303 A emission during solar cycle 21

Technical Report · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5763204

Altrock, R C

Investigation of the behavior of coronal intensity above the limb in Fe XIV emission (5303 A) obtained at Sacramento Peak Observatory over the last fourteen years resulted in the confirmation of a second set of zones of solar activity at high latitudes separate from the Main Activity Zones (MAZ). Localized emission peaks in Fe XIV 5303 A are observed through most of the cycle at latitudes in individual daily scans, annual averages, and solar-cycle summary plots of the location of all local maximum intensities at 0.15R above the limb. These peaks evolve slowly over a period of days, consistent with the rotation over the limb of stable features, in a similar way to the lower-latitude peaks connected with active regions. The high-latitude coronal-activity zones first appear at latitudes of 70 to 80 deg, 2-3 years after solar minimum. They evolve approximately parallel to the MAZ, with the average latitude decreasing at rate of roughly 5-6 deg per year. After their appearance, they are present more or less continuously until the following solar minimum. Near solar minimum, the high-latitude coronal activity zones that appeared after the beginning of Cycle 21 monotonically evolved into the MAZ of Cycle 22. It thus appears that we have evidence for parallel overlapping solar cycles that begin every 11 years but last for approximately 19-20 years.

• Research Organization: Air Force Geophysics Lab., Hanscom AFB, MA (USA)
• OSTI ID: 5763204
• Report Number(s): AD-A-205767/7/XAB; AFGL-TR-89-0058
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CHARGED PARTICLES
EMISSION SPECTRA
IONS
IRON IONS
SOLAR ACTIVITY
SOLAR CORONA
SOLAR CYCLE
SPECTRA
STELLAR ATMOSPHERES
STELLAR CORONAE