stochastic seismic emission from acoustic glories in new active regions of cycle 24 alina donea...

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

Alina Donea

Centre for Stellar and Planetary Astrophysics

Monash University

04/21/23 1GONG2010/SOHO24

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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)

04/21/23 5GONG2010/SOHO24

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