Bihelical Spectrum of Solar Magnetic Helicity and Its Evolution

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2018-08-20
Major/Subject
Mcode
Degree programme
Language
en
Pages
1-11
Series
Astrophysical Journal, Volume 863, issue 2
Abstract
Using a recently developed two-scale formalism to determine the magnetic helicity spectrum, we analyze synoptic vector magnetograms built with data from the Vector Spectromagnetograph instrument on the Synoptic Optical Long-term Investigations of the Sun telescope during 2010 January-2016 July. In contrast to an earlier study using only three Carrington rotations (CRs), our analysis includes 74 synoptic CR maps. We recover here bihelical spectra at different phases of solar cycle 24, where the net magnetic helicity in the majority of the data is consistent with a large-scale dynamo with helical turbulence operating in the Sun. More than 20% of the analyzed maps, however, show violations of the expected sign rule.
Description
Keywords
dynamo, magnetohydrodynamics (MHD), Sun: magnetic fields, turbulence
Other note
Citation
Singh , N K , Käpylä , M J , Brandenburg , A , Käpylä , P J , Lagg , A & Virtanen , I 2018 , ' Bihelical Spectrum of Solar Magnetic Helicity and Its Evolution ' , The Astrophysical Journal , vol. 863 , no. 2 , 182 , pp. 1-11 . https://doi.org/10.3847/1538-4357/aad0f2