Diagnostics of a subsurface radial outflow from a sunspot
We measure the mean frequencies of acoustic waves propagating toward and away from a sunspot employing a spot-centered Fourier-Hankel decomposition of p-mode amplitudes as measured from a set of observations made at the South Pole in 1991. We demonstrate that there is a significant frequency shift b...
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ftcern:oai:cds.cern.ch:299190 2023-05-15T18:22:32+02:00 Diagnostics of a subsurface radial outflow from a sunspot Braun, D Fan, Y Lindsey, C Jefferies, S M 1996-03-15 http://cds.cern.ch/record/299190 eng eng http://cds.cern.ch/record/299190 astro-ph/9603078 oai:cds.cern.ch:299190 Astrophysics and Astronomy 1996 ftcern 2018-07-28T02:55:36Z We measure the mean frequencies of acoustic waves propagating toward and away from a sunspot employing a spot-centered Fourier-Hankel decomposition of p-mode amplitudes as measured from a set of observations made at the South Pole in 1991. We demonstrate that there is a significant frequency shift between the inward and outward traveling waves which is consistent with the Doppler effect of a radial outflow from the sunspot. For p-modes of temporal frequencies of 3 mHz it is observed that the frequency shift decreases slightly with spatial frequency, for modes with degree l between 160 to 600. From the l dependence of the frequency shift, we infer that the mean radial outflow within the observed annular region (which extends between 30 and 137 Mm from the spot) increases nearly linearly with depth, reaching a magnitude of about 200 m/s at a depth of 20 Mm. This outflow exhibits properties similar to flows recently reported by Lindsey, et al. (1996) using spatially sensitive local helioseismic techniques. Other/Unknown Material South pole CERN Document Server (CDS) South Pole |
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CERN Document Server (CDS) |
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English |
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Astrophysics and Astronomy |
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Astrophysics and Astronomy Braun, D Fan, Y Lindsey, C Jefferies, S M Diagnostics of a subsurface radial outflow from a sunspot |
topic_facet |
Astrophysics and Astronomy |
description |
We measure the mean frequencies of acoustic waves propagating toward and away from a sunspot employing a spot-centered Fourier-Hankel decomposition of p-mode amplitudes as measured from a set of observations made at the South Pole in 1991. We demonstrate that there is a significant frequency shift between the inward and outward traveling waves which is consistent with the Doppler effect of a radial outflow from the sunspot. For p-modes of temporal frequencies of 3 mHz it is observed that the frequency shift decreases slightly with spatial frequency, for modes with degree l between 160 to 600. From the l dependence of the frequency shift, we infer that the mean radial outflow within the observed annular region (which extends between 30 and 137 Mm from the spot) increases nearly linearly with depth, reaching a magnitude of about 200 m/s at a depth of 20 Mm. This outflow exhibits properties similar to flows recently reported by Lindsey, et al. (1996) using spatially sensitive local helioseismic techniques. |
author |
Braun, D Fan, Y Lindsey, C Jefferies, S M |
author_facet |
Braun, D Fan, Y Lindsey, C Jefferies, S M |
author_sort |
Braun, D |
title |
Diagnostics of a subsurface radial outflow from a sunspot |
title_short |
Diagnostics of a subsurface radial outflow from a sunspot |
title_full |
Diagnostics of a subsurface radial outflow from a sunspot |
title_fullStr |
Diagnostics of a subsurface radial outflow from a sunspot |
title_full_unstemmed |
Diagnostics of a subsurface radial outflow from a sunspot |
title_sort |
diagnostics of a subsurface radial outflow from a sunspot |
publishDate |
1996 |
url |
http://cds.cern.ch/record/299190 |
geographic |
South Pole |
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South Pole |
genre |
South pole |
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South pole |
op_relation |
http://cds.cern.ch/record/299190 astro-ph/9603078 oai:cds.cern.ch:299190 |
_version_ |
1766201936800907264 |