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A. C. Cadavid, J. K. Lawrence (California State University, Northridge ), T. E. Berger (Lockheed Martin Space and Astrophysics Laboratory)
We study the photosphere/chromosphere energetic connection using a nine hour sequence of SVST images obtained May 30, 1998. The data consist of co-spatial, nearly simultaneous filtergrams of G-band (4305 Å), Ca II K (3934 Å), two (6563 Å) H\alpha channels offset by 0.35 Åand 0.7 Å, and Fe I (6302 Å) magnetograms. The cadence of the G-band and Ca K observations is ~30 s; that of the other images is ~2 min. The pixel scale is 0.06 Mm and field of view 48 X 48 Mm on the Sun. The filtergram resolution is > 0.2 Mm; that of the magnetograms > 0.3 Mm with single magnetogram sensitivity < 150 G. We have co-registered the images to 1 or 2 pixel accuracy. The number distribution of Ca brightenings and of localized changes in magnetic field strength, measured in standard deviations (\sigma ) from the image means, present three different characteristic regimes; that of the magnetic ``free energy'' (a derived measure based on the local variance of magnetic field) presents two. Ca brightenings below 3\sigma show a weak but significant correlation with local magnetic field and free energy. At 3\sigma the strength of the correlation abruptly increases. Above 5\sigma no correlation is apparent, but large magnetic field values appear. Using a mask to remove the network areas, the weakest brightenings (<1.5 \sigma) show anti-correlation with the magnetic field. For 1.5 \sigma to 4.5 \sigma there is no correlation. For selected network examples we follow the time evolution in all observed lines. We find cases in which an increase and then relaxation in the magnetic free energy just precedes a local rise in Ca emission followed by a drop to a lower background level than initially. Work supported in part by NSF-ATM-9987305 and NASA-NAG5-10880.
The author(s) of this abstract have provided an email address for comments about the abstract: acadavid@galileo.csun.edu
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.