Local Helioseismology LPL/NSO Summer School June 11-15, 2007.
Braun HMI/AIA Feb 2006 1 using helioseismology to probe magnetic structures (some selected topics)...
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Braun HMI/AIA Feb 2006 1
using helioseismology to using helioseismology to probe magnetic structuresprobe magnetic structures
(some selected topics)(some selected topics)
NorthWest Research AssociatesNorthWest Research Associates
Colorado Research Associates DivisionColorado Research Associates Division
Doug Braun
NWRA / CoRA
3Braun HMI/AIA Feb 2006
local helioseismology:local helioseismology:
Hankel analysisHankel analysis ring diagramsring diagrams time-distancetime-distance helioseismic helioseismic
holographyholography direct modelingdirect modeling
Gizon & Birch “Local Helioseismology” Gizon & Birch “Local Helioseismology” 20052005
Living Reviews in Solar Physics: Living Reviews in Solar Physics: livingreviews.orglivingreviews.org
4Braun HMI/AIA Feb 2006
selected topics:selected topics: far-side imaging of ARsfar-side imaging of ARs emerging ARSemerging ARS flows on AR-scalesflows on AR-scales seismic models of sunspotsseismic models of sunspots
what’s not herewhat’s not here excitation of waves by flares excitation of waves by flares magnetic (e.g. tachocline) influences on global magnetic (e.g. tachocline) influences on global
modesmodes lots of other thingslots of other things
5Braun HMI/AIA Feb 2006
I. far-side I. far-side imagingimaging
Lindsey & Braun 2000, Science 287, 1799
Braun & Lindsey 2001, ApJ, 560, L189
http://soi.stanford.edu/data/farside
2-skip + 1,3-skip implementation with MDI:
K. Osland and P. Scherrer
6Braun HMI/AIA Feb 2006
far-side imaging with far-side imaging with GONG:GONG:
http://gong.nso.edu/data/farside
see poster: González Hernández, et al.
7Braun HMI/AIA Feb 2006
II. (search for) subsurface II. (search for) subsurface emergence of magnetic fluxemergence of magnetic flux
Braun, D. 1995, Braun, D. 1995, PASP Conf. Series (GONG ‘94)PASP Conf. Series (GONG ‘94), 96, 250 , 96, 250 Chang, H.-K., et al. 1999, Chang, H.-K., et al. 1999, ApJApJ, 526, L53, 526, L53 Kosovichev, A., et al. 2000, Kosovichev, A., et al. 2000, Sol PhysSol Phys, 192, 159, 192, 159 Jensen, et al. 2001, Jensen, et al. 2001, ApJApJ, 553, L193 , 553, L193 Kosovichev, A. & Duvall, T. 2002, BAAS, 34, 791Kosovichev, A. & Duvall, T. 2002, BAAS, 34, 791
•results range from null, irreproducible (my own), to interesting and worth a second look
•none probe very deep, in the range where prediction might be practical (?)
•even without predictive capability, this pursuit is scientifically important
8Braun HMI/AIA Feb 2006
rising flux tube rising flux tube propertiesproperties
thin flux tube calculations (Fan & Gong 2000)
time
vr (rise speed)
two days before emergence:•depth z ~ 60 Mm•speed vr ~ 150 m/s•let diameter ~ fz (ff ≤ ≤ 11 !)•travel-time perturbation
120
fc
fzvr
•rms of single corr. ≥10 s
•can get N~100 correlations (maybe); error of mean ≥ 1s
•direct detection of vr (probably) unlikely, but…?
s
va
10Braun HMI/AIA Feb 2006
III. flows on AR scales (SEE III. flows on AR scales (SEE H8)H8)
ARs as divergent or convergent flows (e.g. Braun et al. 2004)
depth variation: shallow inflows and deeper outflows (e.g. Haber et al. 2004)
vertical vortiticy, kinetic helicity, other indices (e.g. Komm et al. 2005,
SEE POSTER #22)
11Braun HMI/AIA Feb 2006
AR flows with AR flows with time: AR9906time: AR9906
•flows not (simply) related to morphology changes
•complicated vorticity signatures
12Braun HMI/AIA Feb 2006
sunspots as:sunspots as:
Abdelatif, Lites & Thomas 1987, Abdelatif, Lites & Thomas 1987, ApJApJ, , 311, 1015311, 1015Abdelatif & Thomas 1987, Abdelatif & Thomas 1987, ApJApJ, 320, , 320, 884884
Braun, Duvall & LaBonte 1987, Braun, Duvall & LaBonte 1987, ApJApJ, , 319, L27319, L27
1988, 1988, ApJApJ, , 335, 1015335, 1015
absorbersabsorbers
refractorsrefractors
13Braun HMI/AIA Feb 2006
IV. seismic models of IV. seismic models of sunspotssunspots
models (forward & inverse) of sound-speed models (forward & inverse) of sound-speed variationsvariations e.g. Fan, et al. 1995; Kosovichev 1996; Chen et al. e.g. Fan, et al. 1995; Kosovichev 1996; Chen et al.
1998; Kosovichev, et al. 2000; Zhao & Kosovichev 1998; Kosovichev, et al. 2000; Zhao & Kosovichev 2003; Basu, et al. 2004; Couvidat et al. 2004, 2005; 2003; Basu, et al. 2004; Couvidat et al. 2004, 2005; Hughes, et al. 2005Hughes, et al. 2005
models of flowsmodels of flows e.g. Duvall, et al. 1996; Kosovichev 1996; Gizon et al. e.g. Duvall, et al. 1996; Kosovichev 1996; Gizon et al.
2000; Zhao et al. 2001; Zhao & Kosovichev 20032000; Zhao et al. 2001; Zhao & Kosovichev 2003 models of (other) magnetic effectsmodels of (other) magnetic effects: : complex complex
sound-speed, anisotropy,sound-speed, anisotropy, mode conversion, mode conversion, absorption, upper turning point depressions, etc.absorption, upper turning point depressions, etc. e.g. Chen, et al. 1997; Ryutova & Scherrer 1998; Cally, e.g. Chen, et al. 1997; Ryutova & Scherrer 1998; Cally,
et al. 2004; Crouch, et al. 2005; Lindsey & Braun 2005et al. 2004; Crouch, et al. 2005; Lindsey & Braun 2005
14Braun HMI/AIA Feb 2006
sunspot seismology: issuessunspot seismology: issues
keeping in mind that all models keeping in mind that all models are useful and important… are useful and important…
models with similar assumptions models with similar assumptions (e.g only sound-speed (e.g only sound-speed perturbations) often differ perturbations) often differ substantiallysubstantially
including realistic magnetic including realistic magnetic fields in stratified model is very fields in stratified model is very difficultdifficult
no current model is consistent no current model is consistent with (i.e. predicts) all with (i.e. predicts) all observations or known wave observations or known wave interactions in sunspotsinteractions in sunspots
15Braun HMI/AIA Feb 2006
1 vs 2-skip puzzle: Does 1 vs 2-skip puzzle: Does - + + = 2 ?
Braun (1997):Braun (1997): No No (for (for > 150Mm ) > 150Mm )
Zhao & Kosovichev Zhao & Kosovichev (2006): (2006): Yes Yes (for (for =24 – 73 Mm ) =24 – 73 Mm )
Braun (2006): Braun (2006): No No (for (for =35 – 110 Mm ) =35 – 110 Mm )
- : incoming travel-time (center-annulus or ingression-control)
2/2 : (half the) double-skip travel-time (annulus-annulus or
egression-ingression)
+ : “outgoing travel-time (center-annulus or egression-control)
Δ
Δ
16Braun HMI/AIA Feb 2006
absorption: mode absorption: mode conversion?conversion?
slow modes:
Spruit & Bogdan
Cally & Bogdan (1997)
Crouch, et al. (2005)
SEE POSTER #17
Hankel analysis :
phase shiftsabsorption
Holography: :
normalized egression power
17Braun HMI/AIA Feb 2006
Schunker, Braun, Cally, & Lindsey 2005 “Local Helioseismology of Inclined Magnetic Fields and the Showerglass Effect,” ApJ 621, L149
Goal: look for evidence of the conversion of vertically oscillating p-modes to elliptical motion in inclined fields in sunspot penumbrae.
Observations: MDI (SOHO) - helioseismic
IVM (Mees Obs.) – Stokes Method: measure correlation between ingression and direct velocity signal at different projected l.o.s angles (p) in plane of magnetic field.
AR 9026
18Braun HMI/AIA Feb 2006
evidence for elliptical motion (mode evidence for elliptical motion (mode conversion)conversion)
phase modulus
θp
•varies with field strength/inclination
•observed throughout 3-5mHz frequency range
•measured in several spots
•observed in TD measurements (Zhao & Kosovichev 2006)
•not predicted for, or observed in, scalar quantities (e.g. intensity)
projected line-of-sight angle (from vertical)
inner penumbra
middle penumbra
outer penumbra.
19Braun HMI/AIA Feb 2006
challenges:challenges: farside:farside:
how can we calibrate it?how can we calibrate it? how can we improve it?how can we improve it?
emerging ARs:emerging ARs: can we detect direct or indirect effects (e.g. horizontal flows)?can we detect direct or indirect effects (e.g. horizontal flows)? can theories & simulations tell us what to look for?can theories & simulations tell us what to look for?
flows: flows: how do we combine surface (Doppler, feature-tracking) and how do we combine surface (Doppler, feature-tracking) and
subsurface information?subsurface information? what spatial, temporal scales, products, indices are useful and what spatial, temporal scales, products, indices are useful and
help solve physical problems?help solve physical problems? sunspots:sunspots:
how do we exploit all of the observations (1,2-skip, frequency how do we exploit all of the observations (1,2-skip, frequency variations, lines-of-sight angles, absorption, etc)variations, lines-of-sight angles, absorption, etc)
how do we include explicit magnetic effects in forward (and how do we include explicit magnetic effects in forward (and inverse) models?inverse) models?
how can MHD simulations help?how can MHD simulations help?