Cometary Globule (or Tanuki)

CG 4 is one of a small number of objects classified as “Cometary Globules” because they have a round(ish) head and a tail – like a comet.  We don’t have a good understanding of how these objects formed, but it cannot be a coincidence that most (or possibly all) of them are in the vicinity of the Vela supernova remnant, and their tails point back toward it.  CG 4 is in the constellation Puppis, and is about 1,300 light-years from Earth.  It is sometimes called “The Hand of God”.

My daughter says it looks like a tanuki – Japanese for raccoon.  I don’t see the resemblance, but maybe you do?

It has also been noted that the “hand” (or perhaps it is a monster’s mouth) seems to be reaching for that galaxy near the center of the image.  In reality, of course, the galaxy is much farther away than this nebula.  In fact, it is more than 100 million light-years away.

The image was captured at the remote observatory in Australia, and consists of LRGB plus H-alpha data.  There are many ways that these frames could be combined to create a color image, and I tried several of them.  Here is the straight-forward LRGB version:

If you like astrophotos to show what an object might look like visually, this is the kind of image you would choose.  It has lots of stars, and the bigger ones show a variety of colors.  But I find that having so many stars detracts from delicate structure of the nebulosity, which is best revealed in the H-alpha image.  To create the first image above I took the LRGB image and removed the stars completely, then applied the H-alpha frame as a luminance layer.  That achieved my goal of accentuating the nebulosity, but the galaxy was almost completely lost, since it has little H-alpha content.  So I selected just the galaxy from the LRGB image and blended it back into the H(RGB) image.

I’ll be back at Wa-chur-ed Observatory (aka “home”) soon, and will be busy catching up on almost 2 months of chores, but I do still have at least one more image from southern California to share with you, and will attempt to get it ready ASAP.


About Greg Marshall

I am a retired electronics engineer and after a few months of enjoying my leisure I began to miss doing product development. My astronomy hobby always needed new solutions to unique problems, so I decided that whenever I came up with a good solution I would try to make it available to others.

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