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Stochastic Seismic Emission from Acoustic Glories in New Active Regions of cycle 24

Stochastic Seismic Emission from Acoustic Glories in New Active Regions of cycle 24

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Stochastic Seismic Emission from Acoustic Glories in New Active Regions of cycle 24

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  1. Stochastic Seismic Emission from Acoustic Glories in New Active Regions of cycle 24 Alina Donea Centre for Stellar and Planetary Astrophysics Monash University GONG2010/SOHO24

  2. Holographic images of seismic emissions in AR10486 acoustic glory = enhanced seismic emission 5mHz, halo (Braun, Lindsey 1992) Local helioseismic technique: helioseismic holography (Lindsey, Braun 1997) GONG2010/SOHO24

  3. Holographic images of seismic emission in AR • 2.5-4.5 mHz - seismic deficit up to 30 Mm outside of surface mgn regions • >4.5 mHz - seismic deficit in AR only + - acoustic glory (halo of sharply enhanced seismic emission, small, discrete emitters; thin bead strings) - only around large-multipolar AR (15% excess of mean QS) GONG2010/SOHO24

  4. Emitters cluster in strings 1 emitter size=3Mm, acoustic diffraction limit@5mHz 1 emitter : Seismic EG power =1.5%QS Non-magnetic regions or border weak magnetic region (Donea, Lindsey,Braun 2000) GONG2010/SOHO24

  5. Temporal character of seismic emission from acoustic glories / Quiet Sun (QS) GONG2010/SOHO24

  6. Power distribution of 5mHz EG POW emission from acoustic glories / Quiet Sun (QS) HO2=1.51 Hquiet2 Control tests: -points from QS 2 pixel x 2 pixel (2.8 Mm x 2.8 Mm), square region -ingression from QS disturbances that happen to be converging coherently towards the focus rather than emanating from it GONG2010/SOHO24

  7. Acoustic glories from NOAA 11045 07/02/2010 GONG2010/SOHO24

  8. HO2=1.5 Hquiet2 Saturation develops above H2=Hquiet2 Warning: 5 h observations ! GONG2010/SOHO24

  9. More properties of 5mHz seismic glories: • Contamination • Directionality • Beading GONG2010/SOHO24

  10. More properties: Contamination • Distribution of EG POW QS in the right region of QS • Appear to show slight/significant enhancements. • Contamination from the neighborhood by: • Glory-like emission from main AR • 6mHz seismic activity from surrounding plages GONG2010/SOHO24

  11. Acoustic glories from 06 June 2000 Directionality More seismic emitters along the arrow. GONG2010/SOHO24

  12. 00:43 UT 22:24 UT Beading NOAA 8179 15/03/1998 GONG2010/SOHO24

  13. Acoustic glories from NOAA 11046 14/02/2010 GONG2010/SOHO24

  14. Conclusions -seismic emitters are localized seismic sources with episodic temporal behaviour -only a few of these are enough to contaminate the region and produce glories at 5mHz how many? One emitters gives 1.5-5 QS POW) -extended glories 20-30 Mm -they prefer non/low-magnetic areas “well positioned” -acoustic glories surround only large, multi polar ARs -50% of the EG POW in emitters is incoherent noise -50% of the EG POW is coherent emission -wave generation -”mini” source waves are refracted and interfere with coming waves from the source: Khomenko, Collados 2009 -bead-like structure? Emission/generation mechanism GONG2010/SOHO24