Recently I photographed
Sh2-101 and I was so happy with the broadband data that I decided to stop there, even though I had collected a full set of narrowband data as well.
Well...I went back to play with it a bit thinking that I would do an SHO version, when I saw something new. In the upper left side of the image was a structure that was not obvious in the broadband data (it's there, but very faint). I decided to research it and found a paper titled
The Jet-powered Optical Nebula of Cygnus X1 written by Russell, Fender, Gallo, and Kaiser in 2008. In it they describe the collimated outflow of black hole Cygnus X1, and describe this structure as a "jet-blown nebula" resulting from "the strong shock that develops at the location where the collimated jet impacts the ISM. They go on to say "The shell, which is essentially a radiative shockwave, consists of a bow shock front where the gas is in transition to a higher temperature due to collisions and plasma instabilities (e.g. McKee & Hollenbach 1980).The post-shocked gas then enters the optically thin ‘cooling region’, where the over all ionisation level rises then falls as the gas radiatively cools to ∼ 10^4K (e.g. Cox & Raymond 1985). Shock waves are commonly observed in supernova remnants (SNRs), and shocks created from outflows exist in Herbig-Haro objects, where emission lines are produced in the shock wave created by bipolar flows from pre-main sequencestars impacting the ISM (e.g. Schwartz 1983)."
Photographically, I think the image is quite a bit better than the previous broadband only version. However, I decided not to post this as a revision since the focus of the image is actually the jet-blown nebula, and not simply the pretty picture. I hope you find this as interesting as I did. See the mouse-over for a close up.
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