The Cat’s Eye Nebula, formally known as Caldwell 6 and NGC 6543, is a planetary nebula in Draco. Planetary nebula is a confusing term that has nothing to do with planets and everything to do with the life cycle of intermediate mass stars. These are stars that are not massive enough to result in supernovae. As the stars eventually exhaust their supply of hydrogen by fusing it into helium, they are unable to resist the gravitational crushing force of the mass, and the internal heat caused by this contraction causes the cooler outer layer of the star to expand. The star can shed much of its mass due to stellar wind. If the star is massive enough, it will begin burning the helium and forming carbon and oxygen, keeping it alive for a bit longer. The star continues losing mass, and this carbon and oxygen rich gas shell becomes energized by radiation as the atmosphere of the star heats up.
The Cat’s Eye lies about 3,300 light years away with an apparent magnitude of 9.88. The star within the nebula is around 10,000 time as luminous as the Sun, although it is only about 65% the diameter. The core of the shell is 10,000 times more luminous than the outer shell.
I took my normal four minute exposures for the outer shell, 500 in total. I then took 300 exposures of 15 seconds for the inner shell. The inner shell is so bright that you can witness diffraction effects from it, a first for me. I attempted a HDR composition of the image, but automated tools failed so I did my best with a manual method. The inner shell is only about 16 arcseconds in diameter. Over all, I have 37 hours of data acquisition and about 7 hours of calibration, integration, and processing time in this image.
Nearby it is one of the strangest galaxies I have seen, NGC 6552. It has a very peculiar elliptical barred core with a very distinctive ring. This galaxy is 360 million light years distant, making the light from it that hit my telescope of the same age as the Late Devonian period, when plants had just started evolving roots and seeds, and some marine life were beginning to evolve legs.
Also not to be lost in the background, PGC 61111 flaunts its spiral arms. It’s around 368 million light years away.
The full field,
and annotation,
