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Analysis of M51
For my research question I wanted to research the definition of interacting galaxies and determine whether I believed that NGC 5194 and NGC 5195 are actually interacting with each other.
In my research, I discovered the following criteria for interacting galaxies
In my research, I was able to find a research paper that had studied the velocity difference between NGC 5194 and NGC 5195. The velocity difference between NGC 5194 anf NGC 5195 has been mesaured to be 137 km/s +/- 8km/s. This velocity difference is well below the maximum velocity difference accepted for interacting galaxies which is 500 km/s.
The diameter of NGC 5194 is approximately 100,000 light years. The distance between NGC 5194 and NGC 5195 is approximatgely 47,900 light years. This is well within the accepted 3 radii distance. It is also very clear, even just looking at the galaxies, that they are well within the distance of 3 radii of NGC 5194. This is the distance between them from our line of sight, and since it is widely believed that NGC 5195 is actually behind NGC 5194, this might not be a completely accurate distance.
I was unable to find any usful information on the I-band luminosity differences.
From the information I was able to collect I think that NGC 5194 and NGC 5195 are definately interacting with each other. In my analysis, I wanted to see effects that may have been caused by the gravitational force of NGC 5195 on NGC 5194. I made measurements of the length of the arms from the core of the galaxy, and the angles which the arms protrude from the core of the galaxy to see if there is any assymtery between them. My hypothesis is that there will be differences between the spiral arms, because judging from just general appearances it's clear to see that NGC 5195 is having an effect on NGC 5194.
The above image is a contour plot I made of my final image of M51. This contour showcases all pixel counts of 3500 and higher. I did a couple tests with different contour plotting values and thought this showcased the best what I was wanting to measure.
To measure the spiral arms I began from the centre of the galaxy and measured to the tips of the main contoured part of the spiral arm. I determined the centre of the galaxy by picking the point which had the highest pixel count. I made three measurements of how many pixels it was from the core to the arms and took the average. The three measurements were as follows; Arm closest to NGC 5194 (top arm)- 124.05, 124.76 and 123.74 (average = 124.17). Opposite arm (bottom arm) - 111.16, 111.98, and 111.54 (average = 111.56). Using these calculations I determined that the arm which is closest to NGC 5194 is 1.11 times larger then the opposite arm. This clearly demonstrates that there is assymetry between the arms, and that the gravitational effect of NGC 5195 has caused the arm to be pulled away from the core of the galaxy.
I also wanted to see if NGC 5195 had any effect on the tightness the arms were to core of the galaxy. To do this I printed out my image of M51 and made measurements of the angle between the core of the galaxy and the spiral arms. Since the arms are not a set line, and they have thickness I took a measurement of the inside of the arm and the outside of the arm and then took the average. My measurements for the angles were as follows; Arm closest to NGC 5195 - Outer angle = 42.5 and Inner Angle = 37.5 (average = 40) and Opposite arm - Outer angle = 37 and inner angle = 32.5 (average = 34.75). Using these calculations I determined that the arm which is closest to NGC 5195 is 1.15 times larger then the angle of the opposite arm. This demonstrates that the arm on the opposite side is more tightly wound.
After my analysis, and the research I have seen I am confident that NGC 5194 and NGC 5195 are definately interacting.