Celestial hemisphere:  Northern  ·  Constellation: Cygnus (Cyg)  ·  Contains:  HD202198  ·  HD202364  ·  HD202811  ·  HD202863  ·  PK080-10.1
MWP (G080.8-10.6/PK080-10.1 aka Methuselah Nebula) and its neighbour ALV1 (G079.8-10.2) in HOO with RGB stars, andrey_ch
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MWP (G080.8-10.6/PK080-10.1 aka Methuselah Nebula) and its neighbour ALV1 (G079.8-10.2) in HOO with RGB stars

MWP (G080.8-10.6/PK080-10.1 aka Methuselah Nebula) and its neighbour ALV1 (G079.8-10.2) in HOO with RGB stars, andrey_ch
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MWP (G080.8-10.6/PK080-10.1 aka Methuselah Nebula) and its neighbour ALV1 (G079.8-10.2) in HOO with RGB stars

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Description

MWP1 (Motch-Werner-Pakull 1), also known as the Methuselah Nebula (due to its advanced age), was discovered in 1993 by C. Motch, K. Werner and M. Pakull). It is a rarely photographed faint bipolar planetary nebula measuring 13x9' in the constellation Cygnus. It is one of the largest known planetary nebulae with a size of about 15 light years and a distance of about 4.5k light years from Earth, and is also the oldest (estimated to be 150 thousand years old). Unlike typical planetary nebulae, which take about 10,000 to 20,000 years to dissipate below detection levels, this one is visible much longer. The star responsible for this amazing object is also one of the hottest stars known, so hot that it emits large amounts of X-rays.
There are various theories as to why this nebula can still be seen today. A bipolar structure may indicate the presence of a close binary central star or a star with a significant magnetic field. The central star, RX J2117.1+3412, is also a GW Vir pulsating star, a pulsating white dwarf with a very short period (a few minutes to just over an hour) whose luminosity varies due to radial gravitational wave pulsations within itself. In fact, it was the faint but pulsating X-ray emission from its parent star that first brought it to attention. This star is located slightly below the center of the nebula and appears blue.
Unlike most nebulae, the Ha signal in this object is much weaker than the OIII signal (barely visible inside the MWP), despite a total Ha integration of about 80 hours. And although these nebulae are quite faint, MWP1 and ALV1 have approximately the same relative brightness in Ha and OIII.

ALV1 (Alves 1) was discovered by Portuguese amateur Filipe Alves in 2009 and is a faint planetary nebula measuring about 3' 30". Information about this nebula can be found in the article "Discovery of new faint northern galactic planetary nebulae" by A. Acker at al in 2012. ALV1 was discovered while photographing the MWP1 nebula. Although little is known about ALV1, the article discusses that "a very blue star B ~ 18.2m is located approximately 12" from the geometric center of the nebula and may possibly be the central star of this object, thereby increasing the likelihood that it is a planetary planet. Note that it is not uncommon to find a slightly misaligned central star: this may be due to the interaction of the ISM [interstellar medium] and wind, the high proper motion of the central star, the presence of a binary system at the center, or simply some asymmetry of the nebula itself.” Its relatively large size, dimness and lack of clear structure also hint at significant age. The white dwarf's central star is also blue, but much dimmer and still visible in the image.

Faint Ha and OIII clouds are present in the background. Both of the nebulae seem to be immersed in the surrounding OIII arc, which probably forms an outer shell interacting with the interstellar medium, which forms the background Ha radiation. The front of this arch, especially the eastern and western wings, as well as the northern part, contain many interesting small-scale structures.

And now a little about the process of taking this photo. Dry numbers:
2253 subs were captured (257 GB of data) for the period from June to September 2023, of which:
1001x300s Ha (~83 hours)
1072x300s OIII (~89 hours)
90 hours of calibration/cosmetic correction/alignment/weighting and stacking (multiple passes per channel).
And countless hours to process ;)

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