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Titolo:
Active region magnetic fields
Autore:
Howard, RF;
Indirizzi:
Natl Solar Observ, Tucson, AZ 85726 USA Natl Solar Observ Tucson AZ USA 85726 Solar Observ, Tucson, AZ 85726 USA
Titolo Testata:
JOURNAL OF ASTROPHYSICS AND ASTRONOMY
fascicolo: 3-4, volume: 21, anno: 2000,
pagine: 119 - 125
SICI:
0250-6335(200009/12)21:3-4<119:ARMF>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
SUN;
Keywords:
active regions; sunspot groups; group tilt angles;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
15
Recensione:
Indirizzi per estratti:
Indirizzo: Howard, RF Natl Solar Observ, Tucson, AZ 85726 USA Natl Solar Observ Tucson AZ USA 85726 rv, Tucson, AZ 85726 USA
Citazione:
R.F. Howard, "Active region magnetic fields", J ASTROPHYS, 21(3-4), 2000, pp. 119-125

Abstract

The tilt angles of sunspot groups are defined, using the Mount Wilson dataset. It is shown that groups with tilt angles greater than or less than the average value (approximate to 5 deg) show different latitude dependences. This effect is also seen in synoptic magnetic field data defining plages, The fraction of the total sunspot group area that is found in the leading spots is discussed as a parameter that can be useful in studying the dynamics of sunspot groups. This parameter is larger for low tilt angles, and small for extreme tilt angles in either direction. The daily variations of sunspot group tilt angles are discussed. The result that sunspot tilt angles tend to rotate toward the average value is reviewed. It is suggested that at some depth, perhaps 50 Mm, there is a flow relative to the surface that results from a relation rate faster than the surface rate by about 60 m/sec and a meridional dt ift that is slower than the surface rate by about 5 m/sec. This results in a slanted relative flow at that depth that is in the direction of the average tilt angle and may be responsible for the tendency forsunspot groups (and plages) to rotate their magnetic axes in the directionof the average tilt angle.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 16/07/20 alle ore 19:24:50