Skies By Africa

Images of the Heavens By Eric Africa

SH2-157, NGC 7538, M52 and the Bubble Nebula

SH2-157 and Company
This is a busy region in Cassiopeia containing SH2-157 (nicknamed “The Claw”), NGC 7538 (the bright nebula to the lower right), the Bubble Nebula to the upper right, and M52 at the upper rightmost corner. An earlier attempt at capturing M52 and the Bubble nebula can be found <here>.

SH2-157 and NGC 7538 are emission nebulae, large clouds of gas glowing from the radiation of nearby bright stars. M52 is an open cluster of stars and the 52nd entry in Charles Messier’s famous “these are not comets” list. And as described in its <own page in this site>, the Bubble Nebula is a shell of gas being ejected by a massive star that is approaching the end of its short but spectacular life.

This image was taken from our backyard in West Chester, Ohio with a 4” diameter refracting telescope and astronomy CCD camera for a total imaging time of over 21 hours (details below). Colors were captured and mapped into a false-color palette similar to the filters and techniques employed for the Hubble Space Telescope. RGB data was used to map natural colors to the stars.
Constellation: Cassiopeia
When Visible: August - January
Distance: 5,000 Light-years (M52), 7,000 - 11,000 light-years (NGC 7635) <SH2-157, NGC 7538>
Date: August 2009
Location: West Chester, Ohio
Exposure Details:
H-alpha: 8 x 30 Minutes Binned 1x1
SII: 13 x 30 Minutes Binned 1x1
OIII: 21 x 30 Minutes Binned 1x1
R: 6 x 3 Minutes Binned 1x1
G: 6 x 3 Minutes Binned 1x1
B: 6 x 3 Minutes Binned 1x1
Equipment Used: 
Takahashi FSQ-106N on a Takahashi EM200 Temma-II mount. SBIG STL-6303 camera with 8-position filter wheel and Astrodon filters. Externally guided with an SBIG Remote Guide Head on a Borg 45ED refractor.
Acquisition Software: MaximDL, TheSky6, CCDAutopilot 3
Processing Software: MaximDL, Photoshop CS, IrFanView
My personal take on SH2-157:
SH2-157 has been popularly nicknamed The Claw. It definitely does look like its moniker, but to me it resembles the massive mandibles of some huge cosmic bug. Not to dive into neologism, but my Rorschach interpretation of this object was that of the ant lion larva (otherwise known as the doodelbug). However, the strategic position of that bright nebula embedded within SH2-157 reminded me of a photo I once saw in a Time Life book of some big spider-like creature voraciously devouring a poor cricket. That creature's eyes were in an odd spot on that creature's head. SH2-157 looks (to me, anyway!) like a sketch of that creature, complete with massive mandibles and the odd eye placement. I could not, for the life of me, remember what that creature was called. Google and my memory didn't help (I thought for a long time that its designation began with the letter "N"). Anyway, after some creative Googling I finally found it! It's called a Solpugid, or a Solifuge. Common terms: camel spider, wind scorpion, sun spider, among others. And it is actually the subject of quite a bit of urban legends, apparently!

Anyways, enjoy this portrait that includes the Claw. Though I'd like to call it the Ant Lion. Or the Camel Spider. In this composition it looks like it's lunging at the hapless bug that is NGC 7538. And that Bubble in the image just gives this entire image an underwater feel. Which makes me think of the Claw as a cuttlefish going for some poor shrimp!