Astro-Image | Backward Galaxy NGC 4622

Spiral galaxies are common in the universe. This nearly face-on example from the Hubble Telescope is found 111 million light-years away in the constellation Centaurus. Most of them swirl in a direction one might intuitively assume. This one appears to go in a counter-clockwise direction. Analysis using images by the Hubble Telescope show the outer arms moving clockwise instead. Evidence suggests it consumed a smaller companion galaxy which disturbed its rotation.

Drs. Ron Buta and Gene Byrd from the University of Alabama, Tuscaloosa, and Tarsh Freeman of Bevill State Community College in Alabama, observed NGC 4622 in ultraviolet, infrared, and blue and green filters. Their findings were presented to the American Astronomical Society in January 2002.

I downloaded greyscale images of NGC 4622 from the Hubble Legacy Archive site to make this color image. Hubble and other astro-imaging systems collect images in greyscale with their detectors. Filters of various wavelengths are placed in the light path. By using red-filtered, green-filtered, and blue-filtered images, they can be combined into an RGB color composite.

After selecting and downloading the 3 greyscale images, each is adjusted for contrast and brightness. They are colorized with image editing software into red, green, and blue versions. The green and blue images are copy and pasted as layers onto the red layer. The Blending Mode for the layers is set so the three layers mix their colors. Some adjustment might be needed to align the stars in the 3 layers.

More examples of my Astro-Images can be found here.

2 thoughts on “Astro-Image | Backward Galaxy NGC 4622

  1. Hubble does produce some astonishing images.

    I hope they can find a way to keep it going beyond its current end of mission deadline at the end of the decade.

  2. Wonderful photo! Very interesting how you are able to reconstruct a colour image from the RGB captures.

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