Back to forums

Anyone know what this object is (below the Garnet Star in IC 1396)

Off-topic IC1396 IC Objects Deep Sky Nebula
12 replies•294 views
Andrew Rambaut avatar
Andrew Rambaut avatar
Does anyone know what the blue object below the Garnet Star in the Elephant Trunk Nebula (IC 1396) is? This is with Ha-OIII narrowband and I have increased the saturation of the blue a bit so it is actually probably more of a blue-white colour. I presume it is a reflection nebula? This is a 327mm focal length with an ASI2600 so the pixels are 2.36" in size so the object is maybe 60 arcsecs across?
Well Written Engaging
andrea tasselli avatar
andrea tasselli avatar
GM 3-13, a PN.
Andrew Rambaut avatar
Andrew Rambaut avatar
andrea tasselli:
GM 3-13, a PN.

Lovely. Thanks.
Andrew Rambaut avatar
Andrew Rambaut avatar
Thanks @andrea tasselli  That identification got me to this thread: https://www.cloudynights.com/topic/846834-gm-3-13-planetary-nebula-in-cepheus/ which suggests (after some back and forth) that it may be PM 1-333
Andrew Rambaut avatar
Andrew Rambaut avatar
Or possibly https://app.astrobin.com/i/0dolq1  " In SIMBAD, this object is known as PN G100.4+04.6 (a “possible planetary nebula”), while in NED it is surprisingly known slightly differently as PN G100.5+04.7" Anyway, a nice little gem.
andrea tasselli avatar
andrea tasselli avatar
The last two refer to the PN's galactic coordinates so little surprise in a slight difference in the PN/s coordinates (which may either identified by the originator white dwarf or its photometric barycentre)
Andrew Rambaut avatar
Andrew Rambaut avatar
Yes - Simbad has the following:
At coords (J2000.0) 21:40:59.32176 +58:58:38.7768:

Object: IRAS 21394+5844 (Planetary Nebula)

Distance from query: 20.80 arcsec

Other Identifiers:

- PN G100.4+04.6

- IRAS 21394+5844

- PK 100+04 1

- PN PM 1-333

- WISE J214059.32+585838.7
Andrew Rambaut avatar
Andrew Rambaut avatar
I will point a 9.25" SCT at it tonight and see what I can see. Thanks for the help.
Well Written Respectful
Andrew Rambaut avatar
Andrew Rambaut avatar
Another thread mentions a paper (frustratingly not giving the citation) that suggests it is mainly emitting He II/Hß. But I captured it in the OIII frequency with a 3nm bandwidth (Optolong L-Ultimate). This is why I love this hobby - find a little weird blob on an image and dive down a deep rabbit hole. https://www.cloudynights.com/topic/494333-pn-g1004046pm-1-333-a-strange-looking-planetary/ Edit  - found the paper I think: http://doi.org/10.1088/0004-6256/137/5/4140
Engaging
andrea tasselli avatar
andrea tasselli avatar
Andrew Rambaut:
Another thread mentions a paper (frustratingly not giving the citation) that suggests it is mainly emitting He II/Hß. But I captured it in the OIII frequency with a 3nm bandwidth (Optolong L-Ultimate). This is why I love this hobby - find a little weird blob on an image and dive down a deep rabbit hole. https://www.cloudynights.com/topic/494333-pn-g1004046pm-1-333-a-strange-looking-planetary/ Edit  - found the paper I think: http://doi.org/10.1088/0004-6256/137/5/4140

Given the spectra I guess they were wrong. HeII emission while there is weak, with the two strangest emissions being in the OIII and the Ha ones, IOW a typical bi-lobed PN, see:
SPECTROSCOPIC CONFIRMATION OF THE PLANETARY NEBULA NATURE OF PM 1-242, PM 1-318, AND PM 1-333 AND MORPHOLOGICAL ANALYSIS OF THE NEBULAE - IOPscience
Andrew Rambaut avatar
Andrew Rambaut avatar
Given the tight bandwidth for OIII on my filter  (and how bright the object is in this frequency) I agree with you - the main emission must be OIII - that would accord with Table 2 in the paper - so I guess when they say "PM 1-333 is an extended planetary nebula with a high-excitation (He iiλ4686/Hβ up to ∼ 0.9) patchy circular main body containing two low-excitation knotty arcs. A low Ne([S ii]) of ∼ 450 cm−3 and Te([O iii]) of ∼ 15000 K are derived for this nebula. " in the Abstract they mean that these are the unusual features.
Insightful
AstroGinger avatar
AstroGinger avatar
A cosmic fish !
Andrew Rambaut avatar
Andrew Rambaut avatar
Yes - I was thinking the Parrotfish Nebula!