Subsurface Convective Flows within Active Regions

Subsurface Convective Flows within Active Regions

Bradley W. HindmanDeborah A. Haber

Juri Toomre

JILA/University of Colorado

Ring Power Spectra

The modes appear as nested trumpets aligned with the frequency axis.

Cuts at constant frequency produce nested rings that have larger radii for larger frequencies.

Changes in the mode frequencies manifest as changes to the radii of the rings. Therefore, careful measurement of the radii can be used to determine subsurface structure (sound speed, gas pressure, etc.).

f mode

p1 mode

p2 mode

p3 mode

The Effects on p-mode Spectra

TrackedTracked Not TrackedNot Tracked

The above spectra was obtained bystudying the same area on the solardisk. Equatorial rotation results in a speed of ~ 2000 m/s.

This above spectra was obtained by following the same patch of fluid as it rotates across the solar disk. This removes the large rotational velocity.

High-Resolution Ring Analysis (HRRA)

Low-Resolution MappingInflow nearthe surface

Outflow atdepth

High-Resolution Mapping

Flows Around an Active Region

Newly Emerged Region

Smoothed Magnetogram

Contours of the Smoothed Magnetogram

50 G

100 G

150 G

200 G

250 G

InflowsInflow

Outflow

Outflow

Inflow

NOAO 9433

Average of all active regions March 29 – April 24, 2002 [03/29 – 05/21]

Divergence and Curl

Average of all active regions March 29 – April 24, 2002 [ 03/29 – 05/21].◊ 50 G contour◊ 100 G contour◊ 150 G contour◊ 200 G contour

Conclusions

• The boundaries of active regions are zones of inflow, with typical inflow speeds of 20 m/s.

• The cores of active regions generally possess strong outflows (50 m/s), probably the result of outflows from sunspots.

• We see no evidence for systematic vertical vorticity within active regions. (At least at the spatial scale sampled by out HRRA technique.)