Celestial hemisphere:  Southern  ·  Constellation: Hydra (Hya)
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The unusual and faint nebula Sh2-313 (Abell 35) in Hydra, morrienz
The unusual and faint nebula Sh2-313 (Abell 35) in Hydra
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The unusual and faint nebula Sh2-313 (Abell 35) in Hydra

Getting plate-solving status, please wait...
The unusual and faint nebula Sh2-313 (Abell 35) in Hydra, morrienz
The unusual and faint nebula Sh2-313 (Abell 35) in Hydra
Powered byPixInsight

The unusual and faint nebula Sh2-313 (Abell 35) in Hydra

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The unusual, very faint (surface brightness only 26.2 mag/arc-sec2) nebula Sh2-313 (also Abell 35) in Hydra, possibly about 1,200 light years away from us. It may have a diameter of about 5.2 light years, and it covers some 16x10 arcmins of sky, about the same sky area as the much visually brighter but closer and smaller Helix nebula. Sh2-313 has long been considered a planetary nebula but its unusual properties mean that may not be the case. It has a dramatic Oiii emitting parabolic bow-shock around the bright binary pair star BD22-3467, which has a very hot white dwarf companion star. The bow shock suggests that the very fast spinning star pair are actually energising the interstellar medium as they fly through it at 150 km/s (half a million km/hr) causing the bow shock structure. Measurements in the 2010s have concluded that the nebula is probably not a PN, but rather a "Stromgren sphere", in which the star pair is actually ionizing the ambient ISM, not surrounded by a planetary nebula of gas emitted by the star pair as originally thought.

There are a number of distant faint galaxies in this image too, including some shining through the faint nebula.

About 2.5 hours of 1 minute exposures at F/2 with a Hyperstar lens on a C11 Edge HD SCT, with an Optolong L-Enhance dual band narrow band filter (covering Ha, Oiii, Hb). ZWO ASI294MC Pro camera. 10Micron GM1000 mount, unguided. Captured with a ZWO Asiair Pro image capture/mount control device (a ZWO modified Raspberry Pi 4 driven by a ZWO mobile app). Shot from our rural backyard in the Western Bay of Plenty, New Zealand.

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