IC 443 and IC 444 (Gary Imm)

IC 443 and IC 444

This image consists of many different types of deep sky objects located in the constellation of Gemini at a declination of +23 degrees. At lower right, IC 443 (Sh2-248) is a large supernova remnant and molecular cloud. At upper center is IC 444, a small reflection nebula. At upper left is the Sh2-249 emission nebula, along with numerous dark nebulae. At center is the shell fragment from an older SNR (G189.6+3.3), which is unrelated to the IC 443 SNR.

IC 443, the Jellyfish Nebula, is located 5000 light years away. It spans almost 1 degree, about twice the apparent width as our full moon, and is about 70 light-years wide. The image shows the hydrogen, oxygen, and sulfur gas fronts which resulted from the violent star explosion, estimated to have occurred about 10,000 years ago. The remnants of the now dense neutron progenitor star which originated the explosion are located in the center of the SNR.

The morphology of the IC 443 SNR has been long studied and debated. The image shows that it is complex. A 2006 paper concluded that it mainly consists of 2 expanding shells of different diameters, as I show in the mouseover. The left shell is smaller because it is being constrained by a neutral H1 cloud. At the center of the SNR, in the foreground, is an obscuring molecular cloud which darkens the central portion of the SNR.

Although the 2-shell mechanism described above seems plausible, the image to me shows that it is more complex than that. At the bottom of the nebula is an unusual pattern of arcs, expanding downward, that are typically associated with lobe breakthrough, but that doesn’t make sense here. Also, the bright curving S-shape arc pattern (shown in the mouseover) that extends across the SNR has no obvious explanation.

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Status	Advanced success
Started	...
Astrometry.net job	8033213
PixInsight job	NIRQ92JDE7N7VJS0WG7VYJX43X47MJYC
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	06h19m20s.73
RA (top/left)	06h25m35s.66
RA (top/right)	06h13m18s.44
RA (bottom/right)	06h13m11s.78
RA (bottom/left)	06h25m17s.42

Dec (center)	+22°41′20″.10
Dec (top/left)	+23°42′35″.7
Dec (top/right)	+23°46′25″.10
Dec (bottom/right)	+21°39′18″.9
Dec (bottom/left)	+21°35′26″.7

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IC 443 and IC 444

IC 443 and IC 444

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IC 443 and IC 444

IC 443 and IC 444

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