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Thor's Helmet Nebula, NGC 2359, located in the constellation Canis Major.
This image total exposure time (of used subs) was 35 hours through HAlpha and OIII narrowband filters and was imaged through a 8" SCT at 2032mm focal length using a astro-modded and cooled DSLR.
This image was a bit of a challenge with the Australian bushfires sending a lot of smoke into the atmosphere, causing me to throw out a lot of failed subs. 35 hours are the selected best subs I used on this image but have spent a lot more time in tracking this nebula from 30 November 2019 until 4 January 2020.
Here's my latest, and my second experiment in bicolour narrowband:
31x 600s Ha, 29x 600s OIII, 10 each x 180s R, G and B. Flats, darks and bias, equipment as per sig, Pixinsight processed.
Taken over three nights - I'd done a night each on Ha and OIII, but decided I needed a few more OIII (not least since I had a big guiding hiccup which meant that after I'd caught it and lazily not bothered to correct it, half the run were off-centre, though I still used them), so the third night I grabbed about 10 more OIII, but also thought I'd gather a little R,G & B. I've used that RGB just as chrominance only for the stars and a little bit from the blue channel for the 'cage' around the bubble. I've gone through various iterations of green-blue colour balance in processing it - I wanted to be true to the OIII wavelength and leave a decent amount of green in there, but it tends to be a bit overwhelming on some monitors, so I've leaned more towards the blue - hopefully I've found a pleasing balance.
Thor's Helmet (NGC 2359) is an emission nebula in the constellation Canis Major. It is approximately 12 thousand light years away and the central bubble is 30 light-years across. The central star is the Wolf-Rayet star WR7, an extremely hot star thought to be in a brief pre-supernova stage of evolution. It is similar in nature to the Bubble Nebula, but interactions with a nearby large molecular cloud are thought to have contributed to the more complex shape and curved bow-shock structure of Thor's Helmet. Wolf-Rayet stars are characterised by a rapid loss of stellar mass, driven by chemically enriched high-speed stellar winds.
The nebula has an overall bubble shape, but with complex filamentary structures. The nebula contains several hundred solar masses of ionised material, plus several thousand more of un-ionised gas. It is largely interstellar material swept up by winds from the central star, although some material does appear to be enriched with the products of fusion and is likely to come directly from the star. The expansion rate of different portions of the nebula varies from 10 km/s to at least 30 km/s, leading to age estimates of 78,500 - 236,000 years.
Comments and cc welcome, hope you enjoy !