Bihelical Spectrum of Solar Magnetic Helicity and Its Evolution

Nishant K. Singh, Maarit J. Käpylä, Axel Brandenburg, Petri J. Käpylä, Andreas Lagg, Ilpo Virtanen

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)
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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.

Original languageEnglish
Article number182
Pages (from-to)1-11
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 20 Aug 2018
MoE publication typeA1 Journal article-refereed


  • dynamo
  • magnetohydrodynamics (MHD)
  • Sun: magnetic fields
  • turbulence

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