HDW 2 - Sh2-200 (Gary Imm)

HDW 2 - Sh2-200

This object is known by many names - HDW 2 (Hartl-Dengl-Weinberger 2), Sharpless 2-200 and PNG 138.1+4.1. It is a beautiful and mysterious planetary nebula located 3600 light years away in the constellation of Cassiopeia. The bright portion of the nebula is only 6 minutes in diameter.

The Sh2-200 designation was first, recognizing the Ha region but not that this object is a planetary nebula. The HDW trio discovered in 1983 that this object is a PN. The HDW catalogue has 8 other nebulae.

There are so many unusual things that I love about this object. My favorite are the numerous wispy OIII strands which extend diagonally across the nebula. I have not seen an explanation of how this was formed. Another favorite is the gap in the OIII emission which extends all of the way around the circumference, which seems unusual to me. For a third favorite, a bright inner ring of OIII is also evident. And finally a fourth - it is amazing that an arc of bright stars is superimposed over the inner ring from our perspective.

The actual extent of the faint OIII emission is about 40 minutes, making this one of the largest PNs and also one which must be very old. The outer area is filled with Ha, with the strongest region being in a band at the bottom. Most sources I have read believe that this Ha emission also came from the same central star of the PN. I have not seen the actual central star identified - there are several possible candidates in the image.

Finally, the bright cluster of stars to the lower left is Trumpler 3, unfortunately overshadowed by this faint but outstanding object.

Narrowband imaging
Sharpless2 Objects
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All of My PN Images (264)
Ancient PN
Orphaned Beauties Catalog (Complete)
Sharpless Catalog (200/313)

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Status	Advanced success
Started	...
Astrometry.net job	2398454
PixInsight job	RRD917NHGTC0TBTBAD9SRZ2C3F0J6XRO
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	03h11m02s.934
RA (top/left)	03h08m32s.654
RA (top/right)	03h08m20s.766
RA (bottom/right)	03h13m28s.763
RA (bottom/left)	03h13m49s.175

Dec (center)	+62°47′42″.57
Dec (top/left)	+63°12′33″.76
Dec (top/right)	+62°24′01″.56
Dec (bottom/right)	+62°22′41″.95
Dec (bottom/left)	+63°11′11″.26

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HDW 2 - Sh2-200

HDW 2 - Sh2-200

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HDW 2 - Sh2-200

HDW 2 - Sh2-200

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