Rotation of the photospheric magnetic fields - A north-south asymmetry

Journal Article · Sat Sep 01 04:00:00 EDT 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/169120· OSTI ID:6334797

Antonucci, E; Hoeksema, J T; Scherrer, P H ^[1]

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1. Torino Universita, Turin (Italy) Stanford Univ., CA (USA)

During most of solar cycle 21 the large-scale photospheric field rotated more rapidly in the Northern Hemisphere than in the southern. The large-scale northern field rotated with a 26.9 day period (synodic), was centered at 15 degrees N, and covered a latitude zone about 24 degrees wide. The large-scale southern field rotated with a periodicity of 28.1 days, was centered at 26 degrees S, and covered a latitude zone about 32 degrees wide. Our analysis showed rotational power at only a few discrete latitudes and frequencies in each hemisphere. The center of each peak lies near to the sunspot differential rotation curve. The largest scale field contributes to the configuration of the coronal and interplanetary magnetic field (IMF). The strength of the first harmonic of the northern field suggests that this structure may be related to the 4-sector pattern observed in the IMF polarity. The southern field had much lower power at the first harmonic of the solar rotation rate and so would contribute only to a 2-sector structure in the IMF. These results were discovered in Fourier analysis of photospheric synoptic charts obtained at the Wilcox Solar Observatory from 1976 to 1986 and confirmed in higher resolution maps from the National Solar Observatory. Mt. Wilson magnetic field measurements from solar cycle 20 show a similar north-south asymmetry. 29 refs.

• OSTI ID: 6334797
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 360; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ASYMMETRY
ATMOSPHERES
DIFFERENTIAL GEOMETRY
FOURIER ANALYSIS
GEOMETRY
INTERPLANETARY MAGNETIC FIELDS
MAGNETIC FIELDS
MAPS
MATHEMATICS
MOTION
PHOTOSPHERE
ROTATION
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CORONA
SOLAR CYCLE
STARSPOTS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR CORONAE
SUNSPOTS