Abstract


  MAGNETOSEISMIC STUDY OF ACTIVE REGIONS USING MULTI-HEIGHT SDO OBSERVATIONS

  S. Tripathy, National Solar Observatory, stripathy@nso.edu
  K. Jain, National Solar Observatory,
  S. Kholikov, National Solar Observatory,
  F. Hill , National Solar Observatory,
  P. Rajaguru, Indian Institute of Astrophysics, rajaguru@iiap.res.in

P. S. Cally, Monash University, paul.cally@monash.edu
-----------------------------------
The magnetic field of the Sun is manifested at the surface in the form of highly concentrated magnetic structures (sunspots) often surrounded by plages representing large areas of diffuse magnetic field known as active regions. Recent numerical simulations and helioseismic measurements in active regions have demonstrated that the key to the understanding of these complex processes requires a synergy between models and helioseismic inferences from observations. In this context, using data from Helioseismic Magnetic Imager and Atmospheric Imaging Assembly onboard Solar Dynamics Observatory, we characterize the spatio-temporal power distribution in and around active regions. Specifically, we focus on the power enhancements (acoustic halos) seen around active regions as a function of wave frequencies, strength and inclination of magnetic field and observation height as well as the relative phases of the observables and their cross-coherence functions. It is expected that these effects will help us to comprehend the interaction of waves and magnetic fields in the solar photosphere. We will also discuss their implications for theories of mode absorptions and mode conversions.