Active longitudes, nonaxisymmetric dynamos and phase mixing

Details Active longitudes, nonaxisymmetric dynamos and phase mixing Active longitudes, nonaxisymmetric dynamos and phase mixing

Jan 2006

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006a%26a...445..703b&link_type=abstract

Astronomy and Astrophysics, Volume 445, Issue 2, January II 2006, pp.703-714

Astronomy and Astrophysics

Astrophysics

23

Sun: Activity, Sun: Magnetic Fields, Sun: Rotation, Stars: Magnetic Fields, Magnetic Fields

Scientific paper

We discuss the problem of solar active longitudes from the viewpoint of dynamo theory. We start from a recent observational analysis of the problem undertaken by Berdyugina & Usoskin (2003, A&A, 405, 1121) and Usoskin et al. (2005, A&A, 441, 347) who demonstrated from a study of sunspot data that solar active longitudes rotate differentially, with a small but significant asynchrony between northern and southern hemispheres. We suggest two concepts by which the underlying magnetic structure could lead to the observed phenomenology - the true differential rotation of a nonaxisymmetric magnetic structure and a stroboscopic effect. In the latter case, a solid body rotation of nonaxisymmetric magnetic structure is illuminated by an activity wave propagating from middle latitudes to the solar equator, and so mimics a differential rotation. We then discuss several mechanisms which could in principle lead to the excitation of active longitudes. In particular, we consider dynamo excitation of nonaxisymmetric magnetic modes, nonaxisymmetric structures as a manifestation of a relic magnetic field in the solar core, nonaxisymmetric solar hydrodynamics and nonlinear instabilities that lack axial symmetry. We conclude that these mechanisms all provide ways to explain the phenomenology, provided the stroboscopic interpretation is accepted. Of course, a quantitative explanation in the framework of any scenario requires ultimately a detailed numerical simulation. The interpretation of the available observations as a true differential rotation appears to provide a much more severe challenge for theorists. We are unable to suggest a plausible mechanism of this kind; however we can not exclude in principle such an explanation. We relate the phenomenon of solar active longitudes to the information available concerning stellar active longitudes, and also consider evidence from other tracers of solar activity.

Affiliated with

Also associated with

No associations

Rating

Active longitudes, nonaxisymmetric dynamos and phase mixing does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Active longitudes, nonaxisymmetric dynamos and phase mixing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Active longitudes, nonaxisymmetric dynamos and phase mixing will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1278391