Detection of Dynamo Waves Inside the Sun

                                              AAS BriefingMonday, 10 June 2019, 3:00 pm CDT  - 2nd Floor of the St. Louis Union Station Hotel

Contact: Alexander Kosovichev (New Jersey Institute of Technology, alexander.g.kosovichev@njit.edu, phone: 408-239-7984)

AAS Briefing Presentation: Detection_of_Dynamo_Waves_web.pptx

Detailed description.  Kosovichev_Dynamo_Waves_AAS2019.pdf

Publication: Dynamo Wave Patterns Inside the Sun Revealed by Torsional Oscillations
Authors: Alexander G. Kosovichev, Valery V. Pipin, Astrophysical Journal Letters, Volume 871, Issue 2, article id. L20 (2019)  https://arxiv.org/abs/1809.10776

Summary. Torsional oscillations are exhibited by bands of fast and slow zonal flows beneath the visible surface of the Sun, similar to stream jets in the Earth's atmosphere.  Analysis of helioseismology data obtained by two NASA missions in 1996-2018 for nearly  two solar cycles reveals zones of deceleration of torsional oscillations inside the Sun due to a back reaction of magnetic fields generated by the solar dynamo.  Deceleration of the flow originates about 120,000 miles beneath the solar surface at high latitude regions of the solar tachocline.  This zonal deceleration migrates through the convection zone revealing patterns of magnetic dynamo waves, analysis of which explains the phenomenon of the extended solar cycle observed in the evolving shape of the solar corona, and why the polar magnetic field strength predicts the solar maxima. The results indicate a further decline of sunspot activity in the next solar cycle. 

Image caption. Image of the zonal acceleration pattern beneath the solar surface shows zone of flow acceleration (red) and deceleration (blue). The flow deceleration is caused by the magnetic field. The inner sphere shows the bottom of the convection zone (the solar tachocline). The tachocline region marked with A is the primary seat of the solar dynamo, where the magnetic is initially generated.  B and C indicate the polar and equatorial branches of the dynamo wave. When the polar branch reaches the surface it causes polar field reversals, while the equatorial branch, amplified by magnetic field stretching due to differential rotation, leads to formation of sunspots. The insert shows the evolution of the sunspot number during 22 years of helioseismic observations. The image shows a snapshot of the zonal deceleration in 2003 near the maximum of the sunspot number of Solar Cycle 23 (point B), when the generation of magnetic field of the next solar cycle already started in the tachocline (point A). (Visualization by Tim Sandstrom, NASA Ames Research Center). (high-resolution image)

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Evolution of the solar magnetic structure during the last two solar cycles
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Evolution of the zonal acceleration in the solar convection zone reveals traveling dynamo waves

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