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Phase Jumps in Local Helioseismology View all abstracts by submitter

Paul Cally   Submitted: 2008-11-08 13:25

Helioseismic rays trapped in a non-magnetic acoustic cavity suffer a +90 degree phase jump at their lower (Lamb) turning point and -90 degrees at the upper (acoustic cutoff) reflection point. That the two cancel allows local helioseismology to effectively assume that phase is continuous along a ray path joining two surface points. However, in strong surface magnetic field, as found in sunspots, we show - for an isothermal model with uniform magnetic field - that the phase jump for fast magnetoacoustic rays that penetrate the acoustic/Alfvénic equipartition level (c=a) is around -120 degrees. Moreover, there are further negative phase jumps on the upgoing and downgoing legs at c=a which add to the net phase change. Neglecting these effects can lead to a misinterpretation of helioseismic data in terms of travel-time shifts.

Authors: P. S. Cally
Projects: None

Publication Status: Solar Physics (accepted)
Last Modified: 2008-11-09 18:22
Go to main E-Print page  Numerical models of travel-time inhomogeneities in sunspots  Sixty-five years of solar radioastronomy: flares, coronal mass ejections and Sun-Earth connection  Edit Entry  Download Preprint  Submitter's Homepage Delete Entry 

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