Triangulum Galaxy – M33

By Peter Nerbun

This is one of my images of the Triangulum Galaxy, Messier 33. In processing my image I combined the Red, Green, and Blue channel data to yield an RGB image and then applied Luminance channel data to that RGB image thereby yielding an LRGB image.

Please note the large red patches in the upper right corner and lower right quadrant of my image. These areas are known as H-II regions where new stars are born; I’ll explain the physical processes that result in these areas having a reddish color in my description of the second image below. The most prominent of the H-II regions is the nebula NGC604 which as I mentioned appears in the upper right corner of my image. NGC604 measures 1,591 light years in width. It is the largest known H-II region in the entire Local Group of galaxies that extend outward from the Milky Way more than 10 million light years in every direction. The second largest H-II region is nebula NGC595 which is the flame-like red area in the lower right quadrant of my image.

I captured this image with a C-11 SCT and ATIK460EX main imaging camera in 10.5 hours of integration time over multiple nights primarily in Nov 2017.

This is another version of my image of the Triangulum Galaxy. In processing my image I combined the R, G, and B channel data to yield an RGB image and then applied the Luminance channel data to that RGB image. Subsequently I enhanced the Red channel in the RGB image with Hydrogen-Alpha channel data. Finally I combined the enhanced Red channel with Green and Blue channel data to yield an L_HA-R_G_B image.

This process highlights the red “H-II regions” that are interspersed throughout the spiral arms of the galaxy. These H-II regions each include over 200 very hot young blue stars that ionize the surrounding hydrogen atoms; when each ionized hydrogen electron recombines with its proton a photon of light at the hydrogen alpha wavelength of 6563 Angstroms is emitted. That wavelength is interpreted by our brain as a particular shade of red which is why these patches of light appear red in color.

As I noted in the description of my first astrophoto from above, the most prominent of the H-II regions is the nebula NGC604 which appears in the upper right corner of my image. NGC604 measures 1,591 light years in width. It is the largest known H-II region in the entire Local Group of galaxies that extend outward from the Milky Way more than 10 million light years in every direction. As further noted above the second largest H-II region is nebula NGC595 which is the flame-like red area in the lower right quadrant of my image.

I captured this image with a C-11 SCT and ATIK460EX main imaging camera in 12.3 hours of integration time over multiple nights primarily in Nov 2017.

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