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Numerical simulation of effects of reduced excitationof 5-min.solar oscillations in sunspots. Konstantin Parchevsky, Alexander Kosovichev Stanford University, HEPL. Motivation. The amplitude of 5-min. oscillations is significantly smaller in sunspots than in the quiet Sun. - PowerPoint PPT Presentation
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Numerical simulation of Numerical simulation of effects of reduced effects of reduced
excitationof 5-min.solar excitationof 5-min.solar oscillations in sunspotsoscillations in sunspots
Konstantin Parchevsky,Konstantin Parchevsky,Alexander KosovichevAlexander Kosovichev
Stanford University, HEPLStanford University, HEPL
MotivationMotivation
The amplitude of 5-min. oscillations is The amplitude of 5-min. oscillations is significantly smaller in sunspots than in the significantly smaller in sunspots than in the quiet Sun.quiet Sun. Lack of wave sources inside sunspots where Lack of wave sources inside sunspots where
convection is suppressed by strong magnetic convection is suppressed by strong magnetic field.field.
Interaction of incoming waves with magnetic Interaction of incoming waves with magnetic field and perturbations of pressure and field and perturbations of pressure and density inside sunspots.density inside sunspots.
k- k- diagram diagram
l
, m
Hz
Source depth 0.34 , Slice depth = 0 Mm
0 500 1000 1500 2000 25000
1
2
3
4
5
6
7
8
9
10
l
, m
Hz
0 500 1000 15000
1
2
3
4
5
6
7
simulations observations
Artificial maskArtificial mask
x, Mm
y M
m
0 10 20 30 40 50
0
5
10
15
20
25
30
35
40
45
500 10 20 30 40 50
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x, Mm
rela
tive
ampl
itude
Amplitude mapsAmplitude mapsobservations simulations
= 3.65 ± 0.6 mHz
amplitude ratio: 4.0 ± 0.9 4.6 ± 1.0
MDI continuum
120 120 50 Mm3
Amplitude ratio vs.Amplitude ratio vs.sunspot diametersunspot diameter
5 6 7 8 9 10 11 121.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
Sunspot diameter, Mm
Ampl
itude
ratio
ConclusionConclusion
1.1. The suppression of acoustic sources The suppression of acoustic sources inside sunspots can almost entirely inside sunspots can almost entirely explain the reduced oscillation amplitude explain the reduced oscillation amplitude observed in sunspots.observed in sunspots.
2.2. Amplitude ratio of acoustic waves inside Amplitude ratio of acoustic waves inside and outside sunspots depends on and outside sunspots depends on sunspots radii. The bigger radius, the sunspots radii. The bigger radius, the bigger suppression.bigger suppression.
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