Transcript Solar-B XRT Science

TRACE:http://vestige.lmsal.com
Imaging Solar Coronal Structure
With TRACE
Leon Golub, SAO
ISAS - 4 Feb. 2003
http://hea-www.harvard.edu/SSXG/
The SAO Solar-Stellar X-ray Group
• Leon Golub
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Jay Bookbinder
Ed DeLuca
Mark Weber
Joe Boyd
Paul Hamilton
Dan Seaton
• With results from A. Van Ballegooijen, A. Winebarger
and H. Warren
The Major Coronal Physics Problems
1. Why is the corona hot?
2. Why is the corona structured?
3. Why is the corona dynamic & unstable?
Emergence of B into the atmosphere,
and response to B.
Why Use X-rays to Observe Corona?
Heating & Dynamics in ARs
TRACE sees four (or possibly only three)
distinct processes in active regions:
1. Steady outflows in long, cool structures. ◄
2. Transient loop brightenings in emerging
flux areas. Also hot & cool material intertwined –
May or may not be related to TLBs.
3. Steady heating of hot loops (moss). ◄
4. Flare-like events at QSLs (or may be cooling
events predicted by 3.).
Examples of
all four
phenomena
Another example of flows
TRACE Active Region Observations are
not Consistent With Hydrostatic Model
Figure from Aschwanden et al. 2000
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Non-HS Loops are ubiquitous
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courtesy H. Warren
Partial Listing of Recent Papers
About Non-Hydrostatic Loops
• Lenz etal 1999, ApJ, 517, L155.
• Aschwanden etal 2000, ApJ, 531,
1129.
• Winebarger etal 2001, ApJ, 553,
L81.
• Schmelz etal 2001, ApJ, 556, 896.
• Chae etal 2002, ApJ, 567, L159.
• Testa etal 2002. ApJ, 580, in press.
• Martens etal 2002, ApJ, 577,
L115.
• Schmelz 2002, ApJ, 578, L161.
• Aschwanden 2002 ,ApJ, 580, L79.
• Warren etal 2003, ApJ, submitted.
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Small gradient in filter ratio, high n.
Multithread model (a la Peres etal 1994, ApJ
422, 412), footpoint heating.
Flows and transient events in non-hydrostatic
loops.
DEM spread → const. filter ratio.
More passbands may help.
Large range in thread T for some loops.
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Full DEM need at each point.
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Grad T along loops w/flat filter ratio
Contra Martens.
Repeated heating episodes.
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What Needs to be Explained?
• 1. 195A/173A ratio is flat.
• 2. Emission extends too high for hydrostatic
loop (this is debated, though).
• 3. Loop density is high by an order of
magnitude.
• 4. Apparent flows (and some Doppler shifts
measured).
Active Region 8536
How isothermal are these loops?
SUMER Velocities
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Symmetric vs. Asymmetric Heating
Winebarger etal ApJL (2001)
Static vs. Flow Model
High-Conductance Model with
Asymmetric Heating
The Effect of High Conductivity
Footpoints in Transient Heating
1. Initial energy
release along
current sheet
(“spotty”)
2. Footpooint
brightening.
3. Evaporation,
then post-flare
loops.
Comparison: Evaporative Model vs.TRACE Obs.
Moss as TR of Hot Loops
Heating Shut-off vs. Observations
Hot Material in the Corona
Mg XII Ly-α
superposed on
Fe X (log T =
6.9 and 6.0)
Consistent with RHESSI
detection of non-thermal
electrons in “quiescent”
active regions.
END PRESENTATION
Warren & Warshall,ApJL (2001)
March 17, 2000 M1.1:
TRACE 1600 Å Movie
March 17, 2000 M1.1: TRACE
1600 Å Images
March 17, 2000 M1.1: TRACE 1600 Å
Light Curves
TRACE Footpoint vs. BATSE HXR
→HESSI!
The Solar-B Mission
The Solar-B Instrument Complement
1. Solar Optical Telescope with Focal Plane Package (FPP)
- 0.5m Cassegrain, 480-650nm
- VMG, Spectrograph
- FOV 164X164 arcsec
2. EUV Imaging Spectrograph (EIS)
- Stigmatic, 180-204, 240-290Å
- FOV 6.0X8.5 arcmin
3. X-ray Telescope (XRT)
- 2-60Å
- 1 arcsec pixel
- FOV 34X34 arcmin
XRT vs. SXT Comparison
1. Higher spatial resolution: 1.0” vs. 2.5”
2. Higher data rate: 512kB continuous.
3. Ten focal plane analysis filters.
4. Extended low-T and high-T response.
5. FIFO buffer for flare-mode obs.
Solar-B XRT Flight Design
Feed-Thru
Electrical
Graphite Tube
Assem bly
Ascent Vent
2 place s
Camera
Electrical Box
Front Door and
Hinge Ass embly
October 24, 2001
XRT CDR Overview/Systems *
P. Cheimets-1
Science Themes
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Plasma Dynamics
Thermal Structure and Stability
The Onset of Large Scale Instabilities
Non-Solar Objects
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Plasma Dynamics
• Reconnection
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loop-loop interaction
flux emergence
nano-flares
AR jets
macro-spicular jets
filament eruption
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Plasma Dynamics
• Waves
– origin of high speed
wind
– tube waves
– coronal seismology
Figures from Nakariakov et al. (1999):
decaying loop oscillations seen in TRACE can
be used to estimate the coronal dissipation
coefficient.
Re ~ 6 x 105 or Rm ~ 3 x 105 , about 8 orders of
magnitude less than classical values.
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Thermal Structure/Stability
• Physical Properties
– Te, ne, EM
– energetics
– variability timescales
• Multithermal Structure
– steady loops
– filaments
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Onset of Large Scale
Instabilities
• Emerging Flux Region
– twisting/untwisting
– reconnection
• delta Spots
– current sheets
– topology changes
• Active Filaments
– Te, ne
– local heating
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Non-Solar Objects
• Jupiter
– S VII @ 198
• Nearby RS Cvns
• Galaxy Cluster Halos
• Comets
• Any EUVE source
within 1 deg of Sun
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Science Drivers I: Spatial Scales
• “Global” MHD Scales
– Active Regions;
– granulation scales
• Transverse scales
- dT, dn
- dB^ and j
• Reconnection sites
– location
– size
– dynamics
105 km
103 km
101 - 103 km
<10 km
RAM discovery
space
<10 km
Science Drivers II: Time Scales
• Loop Alfven time
• Sound speed vs. loop
length
• Ion formation times
• Plasma instability times
• Transverse motions
• Surface B evolution
times
• ~10
• ~100
sec
sec
• ~1 - 10 sec
• ~10 - 100 sec
• 1 - 100 sec
• minutes - months
Optics Metric