HAO Colloquium Series presents Derek Lamb, Southwest Research Institute

Insights into the Small-Scale Solar Dynamo from Ensemble Analysis of Magnetic Features

The total magnetic flux of the Sun is dominated by fields at small spatial scales. Yet understanding the source of those small-scale magnetic fields has been difficult both from an observational and computational standpoint. In this talk, I consider shallow and deep small-scale dynamo models, and illustrate how observations of the ensemble behavior of magnetic fields may be used to discriminate between them. In particular, I describe a recently published search for signatures of near-surface stretching of magnetic field lines using magnetograms from the Narrowband Filter Imager (NFI) on board Hinode. In that paper, we concluded that there is no shallow or “surface” dynamo on the spatial scales observable by Hinode/NFI: the birth locations of new magnetic features (in relation to previously existing network concentrations) do not have the spatial locality properties one would expect from a shallow dynamo model. This points instead to a small-scale dynamo that operates throughout the depth of the convection zone. The subsurface field is stretched and distorted by turbulence, allowing the small-scale field to emerge at random locations on the photosphere.

Date and time: 
Wednesday, July 23, 2014 - 3:00pm to 4:00pm
2139 - Captain Mary
Event document: