1. Solar Corona Oscillations & the Coronal Heating Problem
Tze Goh, Michael Hahn, Daniel Wolf Savin, Greg L. Bryan
Columbia University
This project is made possible with funding from the National Science Foundation.
Analysis of waves: Region
The pixel of maximum intensity along the line
is the position of the loop.
Intensity was fitted with Gaussian to
determine location of loop.
Layers of the sun
Why is it hotter away from the surface
of the sun ?
Damping curves
We fit to the exponential decay function:
y=Ae
-t/
cos(wt-φ)
Analysis of waves: Time
Different positions of the Gaussian
across time indicates that the loop did
oscillate back and forth
Shift in peak of Gaussian
Peak of Gaussian oscillating back and
forth appears to decay in time.
Energy lost (hypothesis)
v = dy/dt = 63.6kms-1
= 3.27 ± 0.89 mins
⍴ = m/Vol ≅ 1.72 x 109
protons/cm3
Power density lost per loop :
½ mv2
/( Vol) ≅ 3 x 10-11
W cm-3
Energy requirement to heat each loop :
10-29
x ⍴2
≅ 3 x 10-11
W cm-3
Assuming a typical coronal density,
there should be enough energy to
heat the loop.
Results & conclusion
We have measured the dissipation of
an Alfven waves on a coronal loop
and found that it likely has enough
energy to heat the loop.
But we don’t have an accurate
measurement of the proton density
yet.
The next step…
● measure the proton density accurately
● fine-tune the tracking of waves by
measuring its position perpendicular to the
loop
Wavelengths of the sun
(SDO)
We analyzed exclusively in 171Å
channel of the Corona.
Alfven waves
Alfven Waves are like standing waves
travelling along the coronal loops, making the
loops oscillate back and forth.
Hypothesis : energy from the waves
heat the coronal loops and the coronal
region.
Photosphere : 5 x 10
3
K
Chromosphere : 1 x 10
5
K
Corona : 3 x 10
6
K
1600 Å
6 x 10
3
K
Photosphere
304 Å
5 x 10
5
K
Chromosphere
171 Å
1 x 10
6
K
Corona
The solar coronal heating problem asks why temperature is increasing away from the surface of the sun. We hypothesize that the dissipating waves
along coronal loops is responsible for this extra energy. I analysed these waves in IDL to determine if they have enough energy to heat the coronal
loops. We found that there is likely enough energy to heat the loops, but we still need a more accurate measurement of the proton density.
t = 0.4 min
t = 1 min
t = 1.4 min
Intensity
Y - position (arcseconds)
Y - position (arcseconds)
Intensity
Time in Minutes