sjc 2/28/2002steady flows detected in euv loops 1 steady flows detected in extreme-ultraviolet loops...
TRANSCRIPT
SJC 2/28/2002 Steady Flows Detected in EUV Loops
1
Steady Flows Detected in Extreme-Ultraviolet Loops
Winebarger, A.R., Warren, H.,
van Ballegooijen, A. Deluca, E.E., Golub, L.
Presented by
Henry (Trae) Winter III
SJC 2/28/2002 Steady Flows Detected in EUV Loops
2
Why This Paper ?
• NOT because it was short
• Based on observations
• Launching point for a discussion on coronal loop properties– General properties/assumptions– Important equations– Loop heating properties
SJC 2/28/2002 Steady Flows Detected in EUV Loops
3
General Outline
I. General Assumptions About Coronal Loops
II. Basic Equations Used In Modeling & Observing Loops
III. Observations & Interpretations
IV. Critiques
SJC 2/28/2002 Steady Flows Detected in EUV Loops
4
General Assumptions About Stationary Loops
Rosner, Tucker, & Vaina. 1978 ApJ. (RTV)
Serio, et al. 1981, ApJ. (RTVS)
• Symmetrical semicircular loops
• Constant width
• Magnetic field only defines geometry
SJC 2/28/2002 Steady Flows Detected in EUV Loops
5
• For hydrostatic loops: Hottest material is located at the loop top– Caveats
• Rayleigh-Taylor instabilities
General Assumptions About Stationary Loops
SJC 2/28/2002 Steady Flows Detected in EUV Loops
6
General Assumptions About Stationary Loops
SJC 2/28/2002 Steady Flows Detected in EUV Loops
7
• RTVS predicts a steep temperature rise from footpoint to T.R. and slow rise through T.R
• RTVS predicts an observable intensity decrease from footpoint to apex due to an exponential decrease in pressure due to gravity
Predictions About Stationary Loops From RTVS
SJC 2/28/2002 Steady Flows Detected in EUV Loops
8
Basic Equations Used In Modeling Stationary Loops
cRH EEE
2
2
3
2
22
5
0 2
5
ds
dTT
ds
TdTEC
Energy Balance Equation
Conductive
Loss Rate
Radiative Loss Rate
dl
dTTQTPER )(2)( eR nTPE
hh s
sAE expHeating Rate
SJC 2/28/2002 Steady Flows Detected in EUV Loops
9
Basic Equations Used In Observing Loops
dlnTGACF eeij 2
Flux Equation
dTTQTGACF ij )(
Line Ratios
(Isothermal Approximation)
ee
e TTGA
TGA
F
F
22
11
2
1
SJC 2/28/2002 Steady Flows Detected in EUV Loops
10
OBS: A loop in TRACE that showed very little intensity change over two hours
INT: Stable loop structureOBS: A ratio between the TRACE 195Å/171Å
filters as well as CDS line ratios is used as a temp. diagnostic. Temp Constant
K INT: Does not agree with RTVS predictionsOBS: A loop showed showed no exponential
intensity decrease with heightINT: Does not agree with RTVS predictions
Observations & Interpretations I
05.095.510
SJC 2/28/2002 Steady Flows Detected in EUV Loops
11
Figure 1
SJC 2/28/2002 Steady Flows Detected in EUV Loops
12
OBS: Red shift in the SUMER Ne VIII 770 (105.8 K) line which corresponds to a line of sight velocity of 15-40 km s-1 +/- 5 km s-1.
INT: Loop is not in hydrostatic equilibrium but instead has a steady flow.
Observations & Interpretations II
SJC 2/28/2002 Steady Flows Detected in EUV Loops
13
Figure 2
SJC 2/28/2002 Steady Flows Detected in EUV Loops
14
New Model
Use a non symmetric heating function to induce a steady flow and compare numerical solutions to the hydrodynamic problem to the observations
LsL
s
sLAE
hh 2
2exp
22
Lss
sAE
hh
0exp
11
SJC 2/28/2002 Steady Flows Detected in EUV Loops
15
Figure 3
SJC 2/28/2002 Steady Flows Detected in EUV Loops
16
Critiques
• Isothermal approx
• Redshift /Blueshift
• Redshift shift
SJC 2/28/2002 Steady Flows Detected in EUV Loops
17
Critiques
SJC 2/28/2002 Steady Flows Detected in EUV Loops
18
Aschwanden Papers ADS
0
2
4
6
8
10
12
14
16
1994 1995 1996 1997 1998 1999 2000 2001 2002