"The 'claw' of this odd looking 'creature'... is a gas cloud known as a cometary globule. This globule's head, however, has ruptured. Cometary globules are typically characterized by dusty heads and elongated tails...[with] visual similarities to comets, but in reality they are very much different. Globules are frequently the birthplaces of stars, and many show very young [small] stars in their heads. The reason for the rupture in the head of this object is not yet known. The [little, slightly-disturbed PGC 21338 spiral] galaxy to the left of the globule is not really threatened by the 'claw' of the ruptured globule head. The galaxy is huge, further in distance [100mly], and only placed near CG4 by chance superposition." [Based on NASA APOD July 26, 2021].
"The CG4 cometary globule lies about 1,300 light-years away from Earth in the southern constellation of Puppis (the Stern). Its 'head' is 1.5 light-years across, and its 'tail' is about eight light-years long. The head of CG4 is opaque, but glows because it is illuminated by the light from hot newly forming stars. Their energy is gradually destroying the dusty head of the globule, sweeping away the tiny particles which scatter the starlight. The globule shows a faint red glow from [ ionized ] hydrogen.
[Based on interesting info on CG4 at
http://annesastronomynews.com/ ]
This 21.2 hr image with LRGBH filters was processed using PixInsight and PS CS6. The data was collected by DeepSkyWest in Rio Hurtado, Chile in January 2021.
Filters used were FLI 8mm: L: 21x600s, R: 19x600s, G: 24x600s, B: 18x600s: H:12x1800s.
1/26/23: Applied BlurX to the (nonlinear) "threatened" galaxy PGC 21338 and did some further star reduction elsewhere in the image with RC-Astro StarShrink.
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