Sh2-188: The Dolphin or Shrimp Nebula (James E.)

Sh2-188: The Dolphin or Shrimp Nebula

Well, this is one of those targets that (for me) end up on the last resort imaging list. I never found this object particularly interesting - even those images taken by the best imagers - so I tended to avoid it as I knew it would take lots of time to get a decent result. It seems most clear nights the past couple of months have coincided with imaging around the moon, so I needed a SHO target and finally gave in and spent a few nights loading up on Ha. I was surprised I could capture the entire shell with 12 hours Ha. I've included the (Russell Croman's StarXterminator) starless Ha and OIII images for reference.

I was surprised to see a couple of galaxies nearby - left and below image. From SIMBAD, the edge-on spiral is 2MFGC 1144 and the small elliptical is 2MASX J01290399+5822170.

The best description of this planetary nebula I found was a research paper "Sh2-188: a model for a speedy PN" by C. J. Wareing, et al, 2004. Sh2-188 is thought to be an ancient planetary nebula in the galactic disk. It appears to be one-sided with recent observations revealing structure behind the filamentary limb. Sh2-188 is interacting with the interstellar medium (ISM) is best simulated with a “triple-wind” model comprising of the usual “fast” and “slow” interacting stellar winds plus the wind due to motion through the ISM. Simulations at various velocities of the central star relative to the ISM found that a high velocity of 125 km per second best approximates the observed structure. The article suggests that Sh2-188 is younger than previously thought and that much of the mass lost has been swept downstream.

Imaged over several nights: Oct 20-21, 27, 2021.

Final
Original
B
C

B

Description: 12 hrs Ha data_starless

Uploaded: ...

C

Description: 4 hrs OIII data_starless

Uploaded: ...

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Status	Advanced success
Started	...
Astrometry.net job	5170593
PixInsight job	TYX894YOTIK7G44LEEAEU1ONHDS3CH8Q
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	01h30m04s.118
RA (top/left)	01h31m43s.484
RA (top/right)	01h31m47s.571
RA (bottom/right)	01h28m23s.162
RA (bottom/left)	01h28m22s.262

Dec (center)	+58°27′32″.89
Dec (top/left)	+58°11′07″.56
Dec (top/right)	+58°43′40″.53
Dec (bottom/right)	+58°43′53″.39
Dec (bottom/left)	+58°11′22″.16

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