SUPERGRANULES AS PROBES OF SOLAR CONVECTION ZONE DYNAMICS

Supergranules are convection cells seen at the Sun's surface as a space filling pattern of horizontal flows. While typical supergranules have diameters of about 35 Mm, they exhibit a broad spectrum of sizes from ~10 Mm to ~100 Mm. Here we show that supergranules of different sizes can be used t...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2012-04, Vol.749 (1), p.1-4
Main Author: Hathaway, David H
Format: Article
Language:English
Subjects:
ASTRONOMY
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CONVECTION
Dynamics
Equatorial regions
Helioseismology
Latitude
LAYERS
PHOTOSPHERE
PROBES
ROTATION
SEISMOLOGY
SHEAR
Space probes
SUN
Wavelengths
ZONES
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Summary:Supergranules are convection cells seen at the Sun's surface as a space filling pattern of horizontal flows. While typical supergranules have diameters of about 35 Mm, they exhibit a broad spectrum of sizes from ~10 Mm to ~100 Mm. Here we show that supergranules of different sizes can be used to probe the rotation rate in the Sun's outer convection zone. We find that the equatorial rotation rate as a function of depth as measured by global helioseismology matches the equatorial rotation as a function of wavelength for the supergranules. This suggests that supergranules are advected by flows at depths equal to their wavelengths and thus can be used to probe flows at those depths. The supergranule rotation profiles show that the surface shear layer, through which the rotation rate increases inward, extends to depths of ~50 Mm and to latitudes of at least 70[degrees]. Typical supergranules are well observed at high latitudes and have a range of sizes that extend to greater depths than those typically available for measuring subsurface flows with local helioseismology. These characteristics indicate that probing the solar convection zone dynamics with supergranules can complement the results of helioseismology.
ISSN:2041-8205
2041-8213
DOI:10.1088/2041-8205/749/1/L13