Naslov
Differential Rotation of Stable Recurrent Sunspot Groups

Autori
Brajša, Roman ; Vršnak, Bojan ; Ruždjak, Domagoj ; Sudar, Davor ; Roša, Dragan ; Hržina, Damir

Izvornik
Solar Physics (0038-0938) 206 (2002), 2; 229-241

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
meridional motions; solar rotation; velocities; period; cycle; sun; positions; latitude

Sažetak
Stable recurrent sunspot groups from the Greenwich data set which were identified in at least two subsequent solar rotations were traced. The solar rotation was determined by the period method from the time difference of the two central meridian passages of each of the 327 identified groups. Sidereal rotation periods were calculated from the synodic ones by a seasonal-dependent procedure taking into account the details of the Earth's motion around the Sun. Growing recurrent sunspot groups rotate on the average faster than decaying recurrent sunspot groups, while sunspot groups of all types taken together rotate faster than both growing and decaying recurrent sunspot groups. A north-south rotational asymmetry and a cycle-dependence of rotational velocity of recurrent sunspot groups were analyzed. Positive rotation velocity deviations are larger, but less numerous than the negative ones. Signatures of torsional oscillations were not found analyzing the rotation velocity residual of recurrent sunspot groups as a function of the distance from the average latitude of activity.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

POVEZANOST RADA