At the core of this nebula is KPD 0553+1755, a hot subdwarf-type star with a temperature of 17,500K, which is pretty hot! It is around 6,000 light-years away in the constellation Orion. Over the last year of surveying the night sky for new objects, it has become clear that many peculiar Oiii-type nebula are linked in some way to HSD stars.
"Hot subdwarfs are considered to be the compact helium cores of red giants, which lost almost their entire hydrogen envelope. What causes this enormous mass loss is still unclear... Being the stripped cores of red giants, hot subdwarfs turned out to be important markers of peculiar events in stellar evolution ranging all the way from star-planet interactions to the progenitors of stellar explosions used to measure the expansion of our Universe."-S. Geier
Whatever is happening to these stars that makes them lose their shells, it sure does cause them to move very fast in one direction! This is well evidenced by strong bow-shock shape formations in
PaFal1,
Falls 8,
Falls 5,
Falls object 3. This nebula displays a similar behavior, with a bright primary bow shock closest to the HSD, and a secondary faint H-alpha bow shock some distance from the HSD.
I came to know of this nebula through an Oiii survey of the area using a 2600MC duo, L-extreme filter, and rokinon 135mm lens at f/2.2. I followed up with my FSQ106 in Oiii to confirm the smudge which I had detected in my survey:
This thing is clearly a bit too small for my own scopes, so me and Keith Quattrocchi set out to image this with his 16" RCOS telescope and 6200mm camera. It was quite faint, proving to be a challenge to process.
In my research to determine if this nebula was known or not, I didn't encounter a clear answer. These coordinates turn up nothing in CDS, HASH, or PNnet. However, I found an obscure reference in Kohoutek L.'s Version 2000 of the Catalog of Galactic Planetary Nebula. In the catalog, it is listed as "hot subdwarf". I'm not sure if this means he knew of the presence of a nebula here, or if it was just marked as a hot subdwarf star.
Either way, a pretty cool nebula which I haven't seen photographed before!
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