Supersonic Downflows in a Sunspot Light Bridge

We report the discovery of supersonic downflows in a sunspot light bridge using measurements taken with the spectropolarimeter onboard the Hinode satellite. The downflows occur in small patches close to regions where the vector magnetic field changes orientation rapidly, and are associated with anom...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2009-10, Vol.704 (1), p.L29-L33
Main Authors: Louis, Rohan E, Bellot Rubio, Luis R, Mathew, Shibu K, Venkatakrishnan, P
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
ATMOSPHERES
BRIGHTNESS
MAGNETIC FIELDS
MAGNETIC RECONNECTION
MAIN SEQUENCE STARS
OPTICAL PROPERTIES
PHOTOSPHERE
PHYSICAL PROPERTIES
POLARIZATION
SATELLITES
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SPECTRA
STARS
STARSPOTS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
SUN
SUNSPOTS
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Summary:We report the discovery of supersonic downflows in a sunspot light bridge using measurements taken with the spectropolarimeter onboard the Hinode satellite. The downflows occur in small patches close to regions where the vector magnetic field changes orientation rapidly, and are associated with anomalous circular polarization profiles. An inversion of the observed Stokes spectra reveals velocities of up to 10 km s-1, making them the strongest photospheric flows ever measured in light bridges. Some (but not all) of the downflowing patches are cospatial and cotemporal with brightness enhancements in chromospheric Ca II H filtergrams. We suggest that these flows are due to magnetic reconnection in the upper photosphere/lower chromosphere, although other mechanisms cannot be ruled out.
ISSN:1538-4357
0004-637X
2041-8205
1538-4357
DOI:10.1088/0004-637X/704/1/L29