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SH2-188, Simeis 22, The Dolphin Nebula


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I imaged this on the nights of the 7th and 22nd November 2020, unfortunately I lost 5 hours of data as I couldn't get a load of subs rotated to match and it was easier to write that off then spend ages faffing.

This has taken about 10 hours to process and really was a challenge that just took some thinking about in Pixinsight.

I'm particularly pleased with the star colour as the HSV script in PI worked wonders.

I'd like to have double the amount of data, but clear nights are a rarity in the UK.

Just over 19 hours of data, using my GSO/Altair 10" RC Truss, Moravian G2-8300 MKII CCD, iOptron 120EC Mount, Pegasus UPB, Chroma 2" Unmounted Filters, Ultrastar Guide Camera

More Info here: - https://www.astrobin.com/4xynes/

As usual here is the bumf: -

Info/Bumf Credit: T.A. Rector/University of Alaska Anchorage, H. Schweiker/WIYN and NOAO/AURA/NSF

Sharpless 188 (SH2-188, Simeis 22 or the Dolphin Nebula) is an unusual planetary nebula in the galactic disk, approximately 850 light-years away from Earth in the northern constellation of Cassiopeia.

Despite their name, planetary nebulae have nothing to do with planets. The name of planetary nebulae arose in the 18th century because of the visual similarity between some round planetary nebulae and the planets Uranus and Neptune when viewed through small optical telescopes. The name has stuck even though modern telescopes make it obvious that these objects are not planets at all.

When a star with a mass up to eight times that of the Sun runs out of fuel at the end of its life, it blows off its outer shells and begins to lose mass. This allows the hot, inner core of the star (collapsing from a red giant to a white dwarf) to radiate strongly, causing this outward-moving cocoon of gas to glow brightly.

Planetary nebulae last for only about 10,000 years, a fleeting episode in the 10-billion-year lifespan of Sun-like stars. So, over the next several thousand years, SH2-188 will gradually disperse into space, and then the white dwarf will cool and fade away for billions of years. Our own Sun is expected to undergo a similar fate over about 5 billion years from now.

The expanding gas from SH2-188 has a nearly circular shape, but is much brighter to the southeast (lower left). This is because the rapidly moving central star – at about125 km/s – is s creating a bow shock in that direction in the surrounding interstellar medium. Faint wisps of gas can also be seen in the opposite direction, which will eventually dissipate away. SH2-188 is considered to be one of the best examples of interaction between a planetary nebula with the interstellar medium.

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Thanks Neil & Gina, I keep an access database when I see something unusual and then check in Cart Du Ciel when it is visible from my location, I have got about 200 targets in there now and have to admit I am rather taken with the Sharpless Catalogue.

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A fascinating object, thank you for posting. This image prompted me to review the Sharpless Catalogue and I am amazed at the different Nebula it exposed. While starting Astrophotography late in life, I don’t think I will run out of objects to target, just years. Oh for more clear skies in the U.K.

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Thanks everyone for the comments, sorry for the late reply, I have had my head buried up my backside sorting out Brexit problems with my business, as well as sorting out some tuning on my new 26c

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