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Messier 51 (NGC 5194)
Kenton Greene


The famous spiral galaxy, Messier 51 (or NGC 5194) lies 23 million light years away in the constellation Canes Venatici. Appropriately nicknamed the Whirlpool galaxy, it's vibrant eye-catching swirls have made one of the most iconic spiral galaxies in the night sky. M51 was first discovered in 1773 by the French astronomer Charles Messier. Limited by his equipment, he described it as a 'dim cloudy nebula'. Later in 1845, Lord Rosse of Ireland observed a spiral structure. This makes M51 the first galaxy to be labeled as a spiral.

M51 is possibly the most widely recognized spiral galaxy. Its two distinct, tightly wound spiral arms. The light pink areas immediately surrounding the spiral arms are known as emission nebulae. These are areas of extremely hot ionized gas. The light blue patches are reflection nebulae which scatter the light from nearby stars. Both these emission and reflection nebulae are indications stellar nurseys. The blue and pink areas in the spiral arms suggest high concentrations of new star formation. The streaks of gray and black sprinkled throughout the spiral arms are called absorption nebulae. These areas consist of much cooler gasses that can block out the light from nearby stars. M51’s extremely bright, yellow core indicates that star formation is less prevalent. The core houses a population of older stars that have had plenty of time to evolve.

M51 is actually not just one galaxy; it’s two! The bright is actually a dwarf galaxy (Labeled Messier 51b or NGC 5195), which interacts with the Whirlpool Galaxy (M51a) as it passes by. The dwarf galaxy, M51a, is connected to its larger neighbor by a faint bridge of dust. This bridge can be seen in the image. The two galaxies will eventually merge, but it will take another few passes for the merger to be complete.
M51 has an angular diameter of and a distance of parsecs. This means that the linear size of the galaxy is approximately.

Analysis of light outside the visual range can give us deeper insight the structure of M51:

Whirlpool Galaxy

The image on the left is was taken by the Spitzer space telescope, which is tuned to detect infrared wavelengths. This image is a composite of multiple infrared wavelengths that are about ten times the length of any light that we can see. These wavelengths are color coded as follows: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8.0 microns (red).

Infrared light is a good indicator of the tempurature of the source. Shorter infrared wavelengths generally indicate a very high surface tempuratures. The light blue regions around M51b and in the very center of the spiral indicate the presense of extremly dense, hot gasses. The red indicates areas that are cooler but still hot enough to be emmissive. In the infrared, the interactions between M51a and M51b made

The image on the right was taken by Chandara X-ray Observatory, another NASA space telescope, and has revealed around 500 X-ray sources. The image is a composite of several wavelengths ranging from 0.1 to 10 keV. These X-ray wavelengths can be emitted from extremely hot ionized gas. X-ray sources are also evidence extremely high energy interactions, such as X-ray binaries. The core of the spiral has bight concentrations of purple. It is estimated from this high concentration of X-ray emission in the core, that an active galactic nucleus is thought to be home to a Super Massive Black Hole.



Catalouge Admin. "Messier 51 : Whirlpool Galaxy." N.p., 2 June 2015. Web. 4 Apr. 2017.

Admin. "Spitzer View of the Spiral Galaxy M51 (." NASA Spitzer Space Telescope. California Institute of Technology, 05 Nov. 2004. Web. 06 May 2017.

Kilgard, Et Al, R. "M51: Chandra Captures Galaxy Sparkling in X-rays." Chandra :: Photo Album :: Whirlpool Galaxy :: June 3, 2014. NASA, 3 June 2013. Web. 06 May 2017.


Right Ascension (J2000) 13:30
Declination (J2000) 47:12:00
Filters used B (Blue), C (Clear), R (Red), V (Green)
Exposure time per filter B(300 x 10), V(120s x 5), R (60s x 5), C(60s x 5)
Image dimension 1092x736 pixels; 23.8x16.1 arcminutes
Date/time observed March,3 12:05 UT


Data Reduction was carried out through MaxIm, the biases and darks were stacked to create both a master bias and master dark image respectively. Then, the master bias and master dark images were used to calibrate the raw flats for each of the four filters. Next, the 10 flats for each filter were stacked to create one master flat per filter. Finally, the raw data was calibrated in each filter using the master bias, master dark, and master flat. These images were stacked resulting in a master calibrated image for each filter. Then calibrated master images were then color combined to create one color image. The color balance settings used in color combining were R: 1; V: 1; B: 3.5.


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