Sh2-200: The Bear Claw Nebula (Carlos Uriarte)

Sh2-200: The Bear Claw Nebula

HOO + RGB Composition

HDW 2 is a very faint and low surface brightness former planetary nebula, making telescopic observations very difficult. Faint planetary nebulae like this one are best seen in detailed astrophotographs like this one, and even then, long exposures of many hours are still required. While in the past planetary nebulae might have been discovered through direct visual observations, the many discoveries made in the 21st century have been made through photographic means.
This nebula was first discovered by astronomer Stewart Sharpless in 1959 who included it in his catalog of HII regions under the name Sh2-200.

In 1983, astronomers Herbert Hartl, Johann Dengel, and Ronald Weinberger included Sh2-200 in the HDW catalog of possible planetary nebulae. However, it was not confirmed to be a true genuine planetary nebula until 2017, when spectra were taken as part of professional observations. In 1987, further narrowband observations by Herbert Hartl and Ronald Weinberger detected a large, faint outer halo extending beyond the core layer.

One feature that is not fully appreciated or clearly defined in the scientific literature is what are known as ISM-like halos. It is a type of structure that represents the ambient interstellar gas in the vicinity of the planetary nebula but is not physically related to it. Despite being very old and highly evolved, low-surface-brightness planetary nebulae like HDW 2 contain very hot and energetic central stars, which are the remnant cores of the parent star that died and shed its gaseous outer layers. The energy output of some central stars in planetary nebulae is so prodigious that it is capable of ionizing unrelated gas in the immediate vicinity and causing it to glow. The most popular example of this phenomenon is the large halo around NGC 3242.

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Status	Advanced success
Started	...
Astrometry.net job	6507320
PixInsight job	INBS4QVBSPHQFU5TISEXSCRMYST7LS21
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	03h11m07s.505
RA (top/left)	03h14m15s.840
RA (top/right)	03h12m23s.893
RA (bottom/right)	03h07m56s.340
RA (bottom/left)	03h09m53s.423

Dec (center)	+62°48′49″.00
Dec (top/left)	+62°34′58″.53
Dec (top/right)	+63°12′56″.98
Dec (bottom/right)	+63°02′24″.44
Dec (bottom/left)	+62°24′38″.55

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