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

Alina Donea

Centre for Stellar and Planetary Astrophysics

Monash University

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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)

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)

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(Donea, Lindsey,Braun 2000)

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

Temporal character of seismic emission from acoustic glories / Quiet Sun (QS)

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Control tests:-points from QS2 pixel x 2 pixel (2.8 Mm x 2.8 Mm), square region

-ingression from QSdisturbances that happen to be converging coherently towards the focus rather than emanating from it

Power distribution of 5mHz EG POW emission from acoustic glories / Quiet Sun (QS)

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HO2=1.51 Hquiet

2

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Acoustic glories from NOAA 11045 07/02/2010

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HO2=1.5 Hquiet

2

Saturation develops above H2=Hquiet

2

Warning: 5 h observations !

More properties of 5mHz seismic glories:

• Contamination• Directionality• Beading

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Distribution of EG POW QS in the right region of QSAppear to show slight/significant enhancements.

Contamination from the neighborhood by:•Glory-like emission from main AR•6mHz seismic activity from surrounding plages

More properties: Contamination

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Acoustic glories from 06 June 2000

DirectionalityMore seismic emitters along the arrow.

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NOAA 8179 15/03/1998

00:43 UT 22:24 UTBeading

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Acoustic glories from NOAA 11046 14/02/2010

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Conclusions

-seismic emitters are localized seismic sources with episodic temporal behaviour -only a few of these are enough to contaminate the regionand 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