Kinematic frames and "active longitudes": does the Sun have a face?

Abstract

It has recently been claimed that analysis of Greenwich sunspot data over 120 years reveals that sunspot activity clusters around two longitudes separated by 180 degrees (``active longitudes'') with clearly defined differential rotation during activity cycles.In the present work we extend this critical examination of methodology to the actual Greenwich sunspot data and also consider newly proposed methods of analysis claiming to confirm the original identification of active longitudes. Our analysis revealed that values obtained for the parameters of differential rotation are not stable across different methods of analysis proposed to track persistent active longitudes. Also, despite a very thorough search in parameter space, we were unable to reproduce results claiming to reveal the century-persistent active longitudes. We can therefore say that strong and well substantiated evidence for an essential and century-scale persistent nonaxisymmetry in the sunspot distribution does not exist.

14 pages, 1 table, 21 figures, accepted in A&A

References in corpus (2)

• Preferred sunspot longitudes: Non-axisymmetry and differential rotation
• Century scale persistence in longitude distribution: in the Sun and in silico

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• First measurement of the magnetic field on FK Com and its relation to the contemporaneous starspot locations
• Solar active regions: a nonparametric statistical analysis
• Physically motivated heat conduction treatment in simulations of solar-like stars: effects on dynamo transitions
• Role of longitudinal activity complexes for solar and stellar dynamos