HR: 0830h
AN: SH51C-12    [Abstracts]
TI: Clustering Properties of Active Centers During Solar Cycle~23
AU: * Pojoga, S A
EM: sorin_pojoga@pvamu.edu
AF: Prairie View Solar Observatory, Prairie View A&M University, P.O. Box 307, Prairie View, TX 77446 United States
AU: Crawford, F R
EM:
AF: Prairie View Solar Observatory, Prairie View A&M University, P.O. Box 307, Prairie View, TX 77446 United States
AU: Jackson, J J
EM:
AF: Prairie View Solar Observatory, Prairie View A&M University, P.O. Box 307, Prairie View, TX 77446 United States
AB: We continue our study (Pojoga and Cudnik, 2002, Solar Phys. 208, 17) of the distribution of solar magnetic regions during the current solar cycle in order to determine more accurately the characteristics of active region clusters. Synoptic magnetic maps from Kitt Peak National Solar Observatory and H-alpha observations of active regions taken at the Prairie View Solar Observatory are used. We identify clusters of activity by comparing the positions of active centers in successive Carrington rotations. An activity complex is considered if the active center persists for a minimum of 4 solar rotations and its position between two rotations is confined to an interval of ±5 degrees in latitude and ±15 degrees in longitude. The characteristics of clusters, such as lifetimes, rotation rates, and flaring properties are re-examined for the whole period. Our results show that a large percentage of active regions (40 - 50%) is involved in the clustering process. The activity complexes or nests are compact in size and exhibit latitude-dependent rotation rates that are close to (and slightly higher than) the differential rotation of recurrent sunspots. Our analysis reveals a great number of complex nests, which also exhibit high flaring rates, either converging, diverging or parallel. Different characteristics of the nests suggest that they are maintained by repeated injections of magnetic flux rather than by the evolution of the surface magnetic fields. We also examine the link between various nest characteristics and the progression of the solar cycle and compare these results with those from previous activity cycles. Examples of a few nests are shown, emphasizing the evolution of their size, activity level and rotation rate.
DE: 7507 Chromosphere
DE: 7513 Coronal mass ejections
DE: 7519 Flares
DE: 7524 Magnetic fields
DE: 7531 Prominence eruptions
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2005 Joint Assembly