Chris Daly
Montana State University
Solar Physics REU 2007



A little bit about my project and me:
My name is Chris Daly and I've just finished my sophomore year at the New Jersey Institute of Technology.  I'm pursuing a bachelor's degree (though I don't intend to stop there) in applied physics with a concentration in astronomy and a minor in mathematics.  I'm here at Montana State University for the 2007 Solar Physics REU Program, working with Dr. David McKenzie and Dr. B. Ravindra.  The project I am a part of is an attempt to identify the mechanism which is responsible for the heating of the solar corona.  The project looks into the possibility of wave heating, which is the conversion of magneto-hydrodynamic waves, generated inside the photosphere, into shocks outside the photosphere, releasing energy and heating the corona.  What I'e been doing thus far is looking at bright points on the sun (in several bands, which correspond to different heights), where the magnetic fields are strong, for some periodicity which will hopefully be related to the MHD's.

Useful links:
Motana State UniversitySolar Physics
More Project Information
Ghostview (Postscript reader)
Wavlet Transform Tutorial by Robi Polikar

Programs I've Written:
bright2.pro
bright.pro
power_spectra.pro
bessler.pro
light_curves.pro
timeslice_creator.pro


Presentations
Final Presentation

Presentation for Hinode

July 26th





July 19th-23rd, 2007
I've been given a new data set.  here are the movies, light curves, filtered light curves, power spectra, average power spectrum and wavelet analysis.
April 6th, 2007 Calcium II H Movie April 6th, 2007 G Band Movie
April 6th, 2007 Calcium II H Time Slice
April 6th, 2007 G Band Time Slice
April 6th, 2007 Calcium II H Light Curves April 6th, 2007 G Band Light Curves
April 6th, 2007 Calcium II H Filtered Light Curves April 6th, 2007 G Band Filtered Light Curves
April 6th, 2007 Calcium II H Power Spectra April 6th, 2007 G Band Power Spectra
April 6th, 2007 Calcium II H Average Power Spectrum April 6th, 2007 G Band Average Power Spectrum
April 6th, 2007 Calcium II H Power Maps
April 6th, 2007 G Band Power Maps
April 6th, 2007 Calcium II H Bright Point Wavelet Analysis April 6th, 2007 G Band Bright Point Wavelet Analysis
April 6th, 2007 Calcium II H Quiet Region Wavelet Analysis April 6th, 2007 G Band Quiet Region Wavelet Analysis





July 18th, 2007
I've been asked to present my work and it seemed the process with which i made my time slice diagrams was a bit ugly to explain so I created videos which will show the birght point being tracked as well as the timeslice beging taken along with the diagram being made.


July 16th, 2007
These are the phase shift diagrams between the G Band and Calcium II H data from April 19th, 2007.  The lower plots represent the distribution of the phase shifts.
These are the first slides from the Calcium II H and G Band movies, respectively, from April 19th, 2007, just to compare the phase shift diagrams to.

    


1.0-1.2 mHz 1.2-1.4 mHz 1.4-1.6 mHz 1.6-1.8 mHz 1.8-2.0 mHz







2.0-2.2 mHz 2.2-2.4 mHz 2.4-2.6 mHz 2.6-2.8 mHz 2.8-3.0 mHz








3.0-3.2 mHz 3.2-3.4 mHz 3.4-3.6 mHz 3.6-3.8 mHz 3.8-4.0 mHz






July 10th, 2007
I've found the power spectra using wavelet transforms for individual pixels in a bright spot as well as quiet regions in the April 19th, 2007 Calcium II H and G Band data sets, using wavelet.pro, wave_signif.pro, colorbar.pro, bes_filter.pro, and bright.pro, none of which I can take any credit for writing.  Bright.pro is a modified version I made of Ravindra's bright_wave.pro.  The differences are it will process the wavelet transforms for as many datacubes as you enter, and for as many points as you'd like, which will be selected by hand.  It also includes a tvscl image of the first slide of first datacube entered (which should be the Calcium II H data)  with a marker over the point which has been processed.  Bright.pro saves color jpegs of the results, which the original program did not.  The results seem to show more dominant 1-2 mHz oscillations.  I will create a bandpass filter and try again.
April 19th, 2007 Calcium II H Bright Point Wavelet Analysis
April 19th, 2007 Calcium II H Quiet Region Wavelet Analysis
April 19th, 2007 G Band Bright Point Wavelet Analysis
April 19th, 2007 G Band Quiet Region Wavelet Analysis
 

July 5th, 2007
I've gotten a new data set, from April 19th, 2007, which has a much more stationary bright point.  I've rewritten all my macros I used for the March 28th data into programs, which can now be used with any data set.  I created a movie, time slice plot, light curves processed by the bessle function, and power spectra for each individual pixel as well as the average.  The power spectra still seem to be dominated by low 1-2mHz frequencies, though this time, only at a 95% significance level in the averaged data.  There were no freuencies at 99% significance in the averaged power spectrum.  All of this has been done with Calcium II H data.
April 19th, 2007 Calcium II H Movie
April 19th, 2007 G Band Mpeg Movie
April 19th, 2007 Calcium II H Time Slice
April 19th, 2007 Calcium II H Light Curves
April 19th, 2007 Calcium II H Power Spectra
April 19th, 2007 Calcium II H Average Power Spectrum

July 2nd, 2007
I created the power maps for the wavelengths of 1.5-2.0 mHz, 2.0-2.9 mHz, 3.0-3.9mHz, and 5.0-5.9mHz, using a program I modified of Ravindra's, called power_map.pro.  There does not seem to be anything too useful about the bright point in these, most likely because the power maps average over all the frames for each individual pixel and the bright point moves and splits throughout the movie.
March 28, 2007 Power Maps


June 29th, 2007
I created the power spectra for each individual pixel in three separate windows: one stationary window, which always contained the bright point, one unfixed window, which followed the bright point with the method mentioned in the June 19th entry (but now restricted to moving three pixels in both directions), and the 100x100 pixel window whose magnitude summed over all the frames was the least, in an attempt to get a 'quiet' region, a control.  The power spectra were created from the data in the original movies which were run through a high band pass filter, created by Ravindra.  I also found the averaged power spectra for the quiet region, the fixed window, the unfixed window, and also a more localized 3x3 pixel window which followed the bright point as well, essentially the middle 9 pixels of the unfixed window. All power spectra show the 95% and 99% significance levels. There are an overwhelming amount of images so rather than post all them all as jpegs, here are the links to the postscript files containing them, you will need an application such as ghostview to read them.  The data seems to show a great deal of power at around 1.5 mHz.

Unfixed Window Images: Fixed Window Images: Quiet Region Images
Calcium II H Calcium II H Calcium II H
G Band G Band G Band
CN Band CN Band CN Band
Red Continuum Red Continuum Red Continuum
Blue Continuum Blue Continuum Blue Continuum
Green Continuum Green Continuum Green Continuum
Average Average Average
Average (3x3 Pixel)


June 22nd, 2007
I ran the time slices through band pass filters: 0 to 1mHz, 1 to 2 mHz and so on until 9 to 10 mHz.  You can see that there is periodicity in all the wavelengths, but that the amplitude decreases as the frequency increases.
March 28, 2007 Filtered Timeslices

June 19th, 2007
The results from a fixed column in the video not were exactly what I was looking for.  It was obvious the bright point was moving out of the twenty-one pixel range I had created and I would need to follow it if I were going to get a better idea of what was going on, so I created a new program (timeslice_creator) which would try to do just that.  Rather than have a fixed column, I decided to find one for each frame.  This didn't follow the point any better as new bright points were being made elsewhere in the movie.  Instead, I wrote my program to find the column with the maximum value within three pixels to each side of the column with the maximum value from the frame before it in order to narrow down the possibility of looking at the wrong point.  I obtained the first frame's column by finding that column which contained the overall maximum value in that frame, which I know from rdpix, corresponds to the point I want to follow.  This program assumes that the bright point does not move horizontally in the movies any faster than three pixels per time interval, which is a reasonable assumption having watched the movie.  When I plotted the position of the maximum columns vs. time, I did not get as smooth of a function as I had hoped, which meant that new bright points in the columns I was looking at were appearing and diverting the programs attention away from the one I was tracking.  After a quick plot of Calcium II H, it was obvious where the new bright point arose and I edited the program to only search for the maximums in each column in the upper third of the movie, because the point I want never dips below that, whereas the point I did not want never rose above the bottom two thirds in any of the frames in which it caused the problem.  What I got when I graphed out the stacked time slices could not have turned out any better.  The bright point is present throughout the entire image.  It's at one value (along the spatial axis) for about the first half of the image and then splits into two or three values (along the spatial axis) for the rest of the image, which seems to correspond to the movie.  The bright point in the movie was well defined for the first half of the movie until it split up about half way through.  I still need to filter the data in order to look for any periodicity and hopefully find some useful (non five-minute) oscillations in my movies.  Time is on the horizontal axis; the vertical axis represents a spatial dimension.
Calcium II H
Blue Continuum
Green Continuum
Red Continuum
CN Band
G Band








June 18th, 2007
Unfortunately, the program I wrote proved to be too much for mithra, filament, earth, wind, fire, or even gallatin to handle, none of which could allocate enough memory to accomplish what I had hoped to get done in one click of the mouse.  I found the problem when I realized I had three four dimensional arrays with about half a billion elements a piece, I kept lowering the sizes of the arrays and adding more steps until it became apparent it was just too much for one program.  I scrapped it and wrote 6 simple programs (catwok_alligner, blue_cont_alligner, gn_banda_alligner, etc.) which would read and align the data (using mreadfits and xrt_align_cube respectively) for each band and save the new data in a file.  I wrote one more program (timeslice_creator) which would restore those files, find the time slices for each band based on the same max column as Calcium II H, put them in new array, and graph them using tvscl.  Even though its slightly less elegant of a process, being in seven separate programs, rather than run for twenty minutes and display some message that the memory could not be allocated, the entire process finished in about eight minutes, making it far more efficient when done in steps.  The results did not seem to yield anything that was too useful.  It seems that the bright point moves outside my twenty-one pixel window. (These pictures are scaled down from 242 x 512 to 195 x 413)

Calcium II H Blue Continuum
Green Continuum
Red Continuum
CN Band
G Band






June 15th, 2007
I've been working on writing a program that will find the column with the maximum (which corresponds to the bright point I need to study) in the first frame of the Calcium II H movie, read and align all the data (do to any shifting of the observing satellite),  and then average over the column with ten pixels on each side in order to create a single pixel wide slice of the graph that I can then plot next to time slices from the rest of the frames, found with the same maximum column.  This should give me a time-dependent picture of the bright point, assuming it does not move more than ten pixels to either side during the movie.   I opted to use the Calcium II H data to find the maximum because it is easiest to find visually and that allows me to check that I've actually got what I'm looking for with the rdpix procedure.  I use the same maximum column from the Calcium II H movie to create the same graphs for the other five data sets.

June 12th, 2007
I've made videos for March 28, 2007 data in the green continuum, red continuum, blue continuum, Calcium II H, G band, and CN band.  I used mreadfits, xrt_align_cube, and image2movie in order to create these videos.   The Calcium II H most clearly shows a bright point in the upper half of the graph which begins in the first frame and slowly seems to fade or split around half-way through.
Blue Continuum
Red Continuum
Green Continuum
Calcium II H
G Band
CN Band

June 7th, 2007
Today, I finished up the IDL assignment for the tutorials this week.  The assignment was to create a program that would take a function that was a combination of two sinusoidal functions with varying frequencies and amplitudes with some added random background noise and to use Fourier transforms to produce the power spectrum and identify the two frequencies.  The amplitudes were 5 and 2 (chosen arbitrarily by me) with the random noise varying between about -20 and +20,  Even with the noise four times larger than the first amplitude, the FFT (Fast Fourier Transform) found its frequency with at least a 99% accuracy.  However, typically (though not in this image), because the noise was about 10 times as large as the second amplitude, it only found its frequency at a 90% confidence level.  The 90% level also returned some false positives, which were returned at the same frequencies every time the program was run, which is actually kind of funny and makes me question just how random IDL's random number generator is.  This also proves just how useful the Fourier transforms and power spectra are for finding periodicity in seemingly cluttered and useless signals.





Contact Information
Christopher Daly
Solar REU Program
Physics Department, EPS 264
Bozeman, MT 59715

email: cjd37@njit.edu
telephone: (201)-956-1198