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Astronomical Observatory: Cool Images

Astr112 Photography Projects, Spring 2006

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M106, Ryan Poling


The M106 galaxy is located 25 million light years away. It is a type Sb galaxy, or the median between large-bulged Sa galaxies and small-bulged, spindly-armed Sc galaxies. It is located just off the "cup" of the Big Dipper (Ursa Major). The center of the galaxy is a yellowish bulge which consists of older, lower-mass stars (as well as a supermassive black hole), while the arms' blue color indicates regions of explosive high-mass star formation (contrary to what water faucets would have you believe, hotter stars are blue and cooler stars are red). In 1995, radio astronomers discovered that the black hole of M106 was the densest concentration of matter known in the universe up to that point: over 36 million solar masses (36 million suns) in the space of roughly 1/12 to 1/24 of a lightyear. This galaxy is actually a prominent source of radio waves; it emits more radio energy than visible light.The disk of gas around the black hole acts as a maser, or microwave laser, which allows astronomers to measure its distance directly instead of relying on other methods to measure distance, such as Cepheid variables. M106 was host to a supernova in August of 1981, which reached 16th magnitude.

The image above was the result of an Honors project for Astr112. To achieve a higher quality image than what is normally possible with only one exposure, I took a total of 20 images: five in the clear filter, two each in the red and visible filters, and three in the blue filter. Since this is a mosaic image with a North and a South field, I took the above exposures twice, once for the North field and once for the South field, resulting in a total of 20 raw images. I processed the images to remove artifacts, combined all the images in each filter, aligned them to form a mosaic image, and color-combined each filter. Then, I adjusted the brightness settings (gamma, screen stretch, etc.), saturation, and finally manipulated the colors to bring out color detail.

The blue arms in the above image are active sites of young, hot, high-mass star formation. Though they are not readily visible in the above image, the arms also contain bright red HII regions, areas of excited hydrogen gas that are essentially star nurseries. The galaxy showcases two prominent arms, and darker, weblike strands of dust (called, appropriately, "dust lanes") that weave their way throughout the galaxy. The quarter circle on the left of the image is actually an artifact from the nearby magnitude 6 star SAO 44141. In the upper left of the image, NGC 4248 peeks into the frame. M106 is approximately 150,000 lightyears across, similar to our own Milky Way galaxy.

M106: Messier Objects
Astronomy Picture of the Day

Right Ascension (J2000) 12:18:57.8
Declination (J2000) +47:18:16
Filters used blue(B), green(V), red(R), and clear(C)
Exposure time per filter 5x300 seconds in C (N and S)
2x300 seconds in VR (N and S)
3x300 seconds in B (N and S)
Date observed

April 23, 2006 (CBVR)




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