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Messier 64 (NGC 4826)
Ryan Johnson

This large, luminous spiral galaxy is Messier 64 (or NGC 4826), located in the Coma Berenices constellation. Unlike typical spiral galaxies, the spiral arms extending from the core of this galaxy do not appear very noticeable. Because of its appearance in larger telescopes M64 is also nicknamed the "Black Eye Galaxy," the "Evil Eye Galaxy," and also the "Sleeping Beauty Galaxy." M64 is located about 17 million light-years (100 quintillion miles) away from Earth. The galaxy itself is comprised of two counter-rotating disks. The central disk, which rotates clockwise, contains a noticeably dark band of absorbing dust clouds; the outer disk contains mostly gas, but rotates counter-clockwise. The rare occurrence of two counter-rotating disks is likely a result of a smaller galaxy colliding with the larger M64 galaxy, possibly more than one billion years ago. This event also perhaps explain the enormous dust cloud in the central region of M64.

Because of the counter-rotation within the galaxy itself, there is a large amount of star formation occurring, particularly in the inner disk. Higher resolution images of M64 reveal young, hot blue stars are being formed. Large amounts of hydrogen gas are also present, as represented by pink-colored clouds. The combination of the blue stars and the pink gas are barely evident in the above image, surrounding the nucleus of the galaxy. The clear-white region on the outside region of the galaxy informs us that there is a much lower density of stars in that disk, as well as less overall star activity.

Using the Pythagorean Theorem and MaxIm, the size of both the major axis and the minor axis of M64 can be determined; and, from that, the size of M64 in light-years can also be calculated. Based on the images taken from Calvin's telescope in Rehoboth, New Mexico (and the various filters and exposure times used), I measured the angular size of M64's major axis to be approximately 403.38 arcseconds. Multiplying that value (in radians) with M64's distance from Earth, I determined that M64 is around 34,232 light-years in diameter.

That being said, as with any object in space, there is not an exact value for every variable, especially considering the fact that objects in space are moving. Furthermore, different telescopes provide different amounts of detail, which leads to different measurements. In this case, the exposure times of each filter used will vary from other images from other telescopes, meaning that the images themselves will also look differently. As a result, the measurements of the major and minor axis will be slightly different than measurements from other telescopes, such as the Hubble Telescope. Based on my research, the images I took show less detail of dust in M64's outer region compared to other professional images; therefore, my measurement numbers will appear slightly smaller.

To the left is a near-infrared image of M64 taken by two telescopes belonging to the Two-Micron All-Sky Survey (2MASS) located in Mount Hopkins, AZ. You will notice that most of the galaxy looks very similar to the visible image at the top of the page, except that the large dust feature is not visible in the image to the left. The reason is because infrared light at very short wavelengths are able to pass through dust very easily, allowing us to see the light behind the dust.

 

 

To the right is a mid-infrared image of M64 taken by the InfraRed Astronomical Satellite (IRAS) in 1983. The red color indicates that the strongest infrared wavelengths are being emitted from the galactic center, with the blue color indicating a fainter emission. Dust clouds do not allow mid-infrared wavelengths to pass through very easily, only allowing general characteristics of M64 to be revealed. In addition, infrared detection technology was still fairly new at the time of this image, so only low-resolution mid-infrared images were available.

 

In order to reduce the large amounts of data within each image, I did the following:

  1. Eliminate any images with significant imperfections (missing pixels, streaks, etc.).
  2. Create a Master Bias by stacking all bias frames using the Average combination method.
  3. Create a Master Dark by calibrating and stacking all dark frames using the Sigma combination method.
  4. Create a Master Flat by calibrating and stacking all flat frames using the Median combination method.
  5. Reduce the data frames by calibrating each master image, inspecting each image for any clouds.

 

References:

"An Abrasive Collision Gives One Galaxy A 'Black Eye'." The Hubble Heritage Project.<heritage.stsci.edu/2004/04/caption.html>

Caltech Cool Cosmos. <http://coolcosmos.ipac.caltech.edu/cosmic_classroom/
multiwavelength_astronomy/multiwavelength_museum/m64.html
>

Nemiroff, Robert. "M64: The Black Eye Galaxy." Astronomy Picture of the Day, edited by Jerry Bonnell, 18 June 2015. <https://apod.nasa.gov/apod/ap150618.html>.

Wikipedia, "Black Eye Galaxy".

Right Ascension (J2000) 12:56:44
Declination (J2000) +21:40:59
Filters used B (Blue), C (Clear), R (Red), V (Green)
Exposure time per filter B (12@300s), C (25@60s), R (10@60s), V (4@300s)
Image dimension 1092x736 pixels; 23.8x16.1 arcminutes
Date/time observed March 15, 2017, 19:27 UT

 

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