News & Events

HEPL / KIPAC Seminar

Thursday, September 1, 2016

S.P. Rajaguru

Indian Institute of Astrophysics, Bangalore

Large- and small-scale flows on the Sun: helioseismic and surface measurements, and implications for dynamo mechanisms

Abstract: Large-scale organised, as well as smaller scale turbulent convective flows throughout the solar convection zone are thought to be crucial to solar magnetism and its sustenance. In this seminar, deriving on results from recent measurements, I discuss two specific flow structures: the large-scale meridional circulation and small-scale photospheric (surface) vortical flows.

In the first part, following a summary of well established observational results on solar meridional flow in the near-surface layers, I discuss recent time-distance helioseismic measurements of the deep structure of the circulation, which differs widely in these measurements. I discuss also possible sources of such differences, and limitations due to noise and large systematics of unknown origins.

I then compare these new helioseismic inferences with available theoretical/numerical models of meridional circulation, and discuss the implications for solar dynamo models that employ it as a key dynamical component. In the second part, I present a study of the relationships between vortical flows and magnetic fields in the solar photosphere from local correlation tracking (LCT) measurements of convective granules imaged by SDO/HMI. Magnetic inhibition of flows due to Lorentz forces are inferred to play dominant roles in these interactions.

I discuss the implications of these results for local dynamo action, if present, in the solar photospheric layers.

Bio: Not Available

Time: 1:30 – 2:30pm

Location: Physics/Astrophysics Bldg., Kistler Conference Rooms 102/103 (Map)

(Light refreshments at1:15pm; Presentation begins at 1:30pm)

Open to All