How Sensitive are Helioseismic Mode Parameters and Subsurface Flows to Choice of the Spectral Line?
Abstract
We analyze simultaneous multi-spectral line observations to investigate how the results of helioseismology are affected by the spectral line used to observe the solar oscillations. The data sets include observations obtained with the Ni I 676.8 nm (from Global Oscillation Network Group - GONG), K I 769.9 nm (from Magneto Optical Filters at Two Heights - MOTH experiment) and Na I D2 589.0 nm (from MOTH experiment and Mount Wilson Observatory) lines during the Austral summer of 2002-03. The depth formation of these lines occurs about 200 km, 420 km and 780 km above the base of the photosphere, respectively. The simultaneous observations in several atmospheric layers allow us to determine the propagation behavior of acoustic waves between these layers. We carry out ring-diagram analysis, a local helioseismology technique, to study the relative changes in local mode parameters and subsurface velocity fields inferred from the different data sets. Preliminary analysis of the mode parameters obtained from the Ni I 676.8 nm and K I 769.9 nm spectral lines clearly show a significant increase in mode amplitude with increasing observing height but with no apparent change in the mode width.
- Publication:
-
AAS/Solar Physics Division Meeting #37
- Pub Date:
- June 2006
- Bibcode:
- 2006SPD....37.0511H