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Holography

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Holography & HMI. NorthWest Research Associates, Inc. Colorado Research ... power between 5-7 mHz computed in subjacent vantage with focus at surface. ... – PowerPoint PPT presentation

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Title: Holography


1
Holography HMI
D. Braun, C. Lindsey, A. Birch
(NWRA/CoRA) collaborators P. Cally, A. Donea,
H. Schunker (Monash U.), J. Werne, M.
Woodard (NWRA/CoRA)
  • NorthWest Research Associates, Inc.
  • Colorado Research Associates Division

2
HMI Science goals for holography
  • farside imaging
  • space weather prediction
  • AR evolution
  • flows
  • physics of solar convection
  • magnetic flux transport and emergence
  • active regions
  • structure and evolution of ARs
  • flares
  • physics of flares
  • flare as point-source for local helioseismology

3
helioseismic holography
H- ingression
H egression
4
acoustic power holography
(space-time domain)
egression,ingression
(z depth,r horizontal position, ? surface
amplitude, G Greens functions)
egression,ingression power
sensitive to sources, sinks at focus
5
Seismic images of a solar flare
  • X2.6 1996 July 7 (AR 7978)
  • propagating waves (Kosovichev Zharkova 1998,
    Nature, 393, 317)
  • acoustic power holography to image source (Donea,
    Braun Lindsey 1999, ApJ, 513, L146)
  • only acoustic flare signature until

6
2003 Oct 28, X17 flare (AR 486)
A. Donea (Monash U.) C. Lindsey (NWRA)
100 Mm
1100 UT
instantaneous egression power between 5-7 mHz
computed in subjacent vantage with focus at
surface.
1110 UT
1125 UT
7
phase-correlation holography
(space-frequency domain)
egression, ingression
correlation
correlation phase
travel-time perturbation
sensitive to refractive perturbations at focus
8
farside imaging
Braun Lindsey (2001, ApJ, 560, L189)
9
AR 486
first appeared on farside
2003 Oct 16
2003 Oct 3
2003 Nov 12
2003 Oct 30
ARs 486,488 on farside
http//soi.stanford.edu/data/farside
10
phase-sensitive holography of flows
N
W
E
S
egressions and ingressions in 4 quadrants
e.g. E-W correlation phase
velocity
11
1999 April 20, focus 3 Mm
12
supergranulation and moat flows
13
holographic flow kernels (A. Birch)
14
supergranular depth sensitivity
div vh pupil
v ? e-z/zo cos(?z/z1) zo 2.5 Mm. red crosses
no return flow (z1 ??). green circles z1 5 Mm
black diamonds z1 15 Mm.
(Braun, Birch, Lindsey 2004 SOHO/GONG
Proceedings)
15
horizontal divergence (smeared to 7.5)
16
vertical vorticity (smeared to 7.5)
vort vh (1/cosB) ?( cosB vB ) / ?L
(1/cosB)?vL / ?B
17
vorticity and rotation rate near ARs
N hemisph. S hemisph.
  • slight association of ARs with positive vertical
    vorticity
  • sunspots tend to occur near the boundaries of
    regions of opposite zonal shear
  • excess rotation rate in ARs

(Braun, Birch, Lindsey 2004 SOHO/GONG
Proceedings)
18
time and longitude-averaged flows
19
probing the tachocline
20
the showerglass effect
21
showerglass assessmentlocal control correlations
  • quiet Sun
  • control (expect C 1)
  • magnetic region
  • C- describes how surface fields shift phase and
    amplitude of local photospheric signature of
    incoming waves
  • C describes influence of field on outgoing waves

? local acoustic amplitude
22
Lindsey C. Braun, D.C. 2005 The Acoustic
Showerglass I. Seismic Diagnostics of
Photoshperic Magnetic Fields, ApJ (in press)
-The Acoustic Showerglass II. Imaging Active
Region Subphotospheres, ApJ (in press)
23
application of showerglass correction
?c lt 250 m/s
7.0 Mm
uncorrected corrected
focus 4.2 Mm
8.4 Mm
5.6 Mm
9.7 Mm
24
application of showerglass correction to
horizonal-flow signatures
focus depth 3 Mm 5 Mm
7 Mm
no correction
showerglass corrected
25
Schunker, Braun, Cally, Lindsey 2005 Local
Helioseismology of Inclined Magnetic Fields and
the Showerglass Effect, ApJL submitted
26
HMI tasks for holography
  • farside imaging
  • upgrades, software rewrites
  • investigate high-? egression power maps for
    near-limb ARs
  • flows
  • f-mode holography for near surface
  • forward and inverse modeling
  • adaption of farside codes to deep interior
  • active regions
  • understand showerglass effects (surface phase and
    amplitude distortions) for correcting subsurface
    signatures
  • flares
  • diagnostics of seismic flare emission (why
    relatively rare?)
  • artificial data for testing local helioseismology
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