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Abstract: Using a high cadence imaging spectropolarimetric observation of a sunspot andits surroundings in magnetically sensitive FeI 6173 A and insensitive FeI7090 A upper photospheric absorption lines, we map the instantaneous wavephases and helioseismic travel times as a function of observation height andinclination of magnetic field to the vertical. We confirm the magneticinclination angle dependent transmission of incident acoustic waves into upwardpropagating waves, and derive 1 proof that helioseismic travel times receivedirection dependent contributions from such waves and hence cause errors inconventional flow inferences, 2 evidences for acoustic wave sources beneaththe umbral photosphere, and 3 significant differences in travel timesmeasured from the chosen magnetically sensitive and insensitive spectral lines.



Author: S.P. Rajaguru 1, R. Wachter 2, K. Sankarasubramanian 3, S. Couvidat 2 1 Indian Institute of Astrophysics, Bangalore, India 2 Hans

Source: https://arxiv.org/







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