Supersonic Continuation of the Evershed Flow Outside a Sunspot as Observed with Hinode
We report on the discovery of mostly horizontal field channels just outside sunspot penumbrae (in the so-called 'moat'region) that are seen to sustain supersonic flows (line-of-sight component of 6 km s-1). The spectral signature of these supersonic flows corresponds to circular polarizati...
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Published in | Astrophysical journal. Letters Vol. 701; no. 2; pp. L79 - L82 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
IOP Publishing
20.08.2009
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Online Access | Get full text |
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Summary: | We report on the discovery of mostly horizontal field channels just outside sunspot penumbrae (in the so-called 'moat'region) that are seen to sustain supersonic flows (line-of-sight component of 6 km s-1). The spectral signature of these supersonic flows corresponds to circular polarization profiles with an additional, satellite, third lobe of the same sign as the parent sunspot' Stokes V blue lobe, for both downflows and upflows. This is consistent with an outward directed flow that we interpret as the continuation of the magnetized Evershed flow outside sunspots at supersonic speeds. In Stokes Q and U, a clear signature of a transverse field connecting the two flow streams is observed. Such an easily detectable spectral signature should allow for a clear identification of these horizontal field channels in other spectropolarimetric sunspot data. For the spot analyzed in this paper, a total of five channels with this spectral signature have been unambiguously found. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 1538-4357 0004-637X 2041-8205 1538-4357 |
DOI: | 10.1088/0004-637X/701/2/L79 |