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Session 1 - Chromosphere, Corona, Flares.
Display session, Friday, June 27
Ballroom B, Chair: Charles Kankelborg

[1.05] Multiple Reversals in Ca II K Profiles

K. S. Balasubramaniam (NSO/SP and PL/GPSS)

The Ca II K spectral line serves as a diagnostic for plasma properties, activity levels and magnetic influence of the chromosphere in the Sun and stars. Traditionally, the K line exhibits a double reversal with well identified spectral features, K1, K2 and K3. This research note presents observations to show that the K line exhibits multiple spectral reversals in addition to the well known features. These multiple reversals are seen only at high spatial and spectral resolution, in solar active regions. The locations of these multiple reversals are cospatial with local H-alpha brightenings that appear at foot-points of dark active region H-alpha fibrils (or active region filaments). The magnetic field structure at the photosphere at the spatial locations where these multiple reversals are observed, are either bipoles (small opposite polarity magnetic nodules) or neutral lines. A compendium of Ca II K spectral lines are presented to demonstrate the nature of these these multiple reversals.

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