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A new "old" visual planetary nebula, and three others in Cygnus

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#1 Redbetter

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Posted 03 September 2019 - 03:18 AM

During some sessions this past new Moon, I targeted four planetary nebulae with the 20" that I had not logged previously.  I struck out (sort of) on one of them, but the others were seen.  The surprise was MWP 1, the Methuselah Nebula in Cygnus, south of 66 Cygni. 

 

I was not aware of MWP1 until a recent image was posted in a thread by CCDer.  The image was beautiful and I wondered why I had not heard of this nebula before.  I found the MWP 1 designation and checked Wikisky...and there was nothing there.  Zooming out I found something that looked like nebulosity well to the southwest of the position in Wikisky (south of 7th mag HD 202811 rather than east of it.)  Although tenuous, the blue hue in the DSS2 images suggested it would respond to an OIII filter, so I decided to give the area a quick look the next time out.  Unfortunately, it is not in Uranometria, even under its PK 80-10.1 or PN G80.3-10.4 designations.  

 

Before I get to the observations, let's consider what makes this planetary interesting other than being missing from Uranometria:  The moniker "Methusaleh" refers to the extreme age of this nebula, ~150,000 years, ancient for planetary nebula which typically dissipate in a few tens of thousands of years.  This makes it one of the oldest planetary nebula known.  The shell is now 13x9 arc minutes across, roughly 17 light years wide, at a distance of about 4500 light years.  (Link.)  The central star is a "PG 1159 star" that is transitioning into the hot portion of the white dwarf stage.  The star, RX J2117.1 + 3412, glows at 13.2 V mag at 150,000 degrees.  The resulting short wavelength emissions including soft x-rays.

 

For my first observation I had not researched the nebula, made a finder chart, or even considered where the central star might be in the busy field.  Instead I had just marked a spot in Uranometria where I expected the planetary to be.  I suspected that the brightest and broadest section of the nebula to the south would have sufficient intensity to be seen with a filter in dark transparent sky (21.70 MPSAS).  I started with a 31T5 for 81x and employed a DGM NPB to cover OIII, H-beta, and H-alpha.  This worked and I had little trouble seeing this section as a diffuse glow.  I then switched to the TeleVue OIII filter to further increase contrast and selectivity if the primary visible emission was OIII.  This both confirmed the NPB impression and provided somewhat greater contrast by darkening the surrounding sky. 

 

I researched a little more at home, printed a chart with the central star marked, and returned to MWP 1 again hoping to see the ends of the bipolar arcs east and west.  Unfortunately, seeing conditions were poorer and despite trying OIII with the 31, 20, and a 16mm eyepiece I was never certain that I was seeing true nebulosity on either end because of the difficulty of resolving the faintest field stars in the are.  I did confirm that I had impressions of some very faint glow extending past the central star, but it was very tenuous.  The very blue white central star was easily identified and was even more prominent among the other field stars when filtered.

 

Contrasting against the very old MWP 1, I observed NGC 7027, a very young planetary nebula that is very small.  Somehow I had never targeted it before (at least that I could find record of.)  This one has various nicknames including the "Pink Pillow Nebula" (Hubble images), Gummy Bear Nebula, etc.  It is small both in apparent size and real size, because it is only about 600 years old.  The nebula is unusually massive, 3 to 4 solar masses and is quite intense in brightness, appearing at moderate power as a comatic out of focus star.  Higher power revealed a compact boxy object with partitions into three sections with a bright knot in one (preceding edge) that was so intense as to appear to obscure a bright star.   

 

The other fun one was NGC 7048, also in Cygnus.  It was bright and easy, of moderate size.  At first with 156x and an OIII filter I thought it had some bipolar arcs on one end of the otherwise round body.  But employing 227x revealed that one of the extensions was a very faint field star just off one northern edge and the other was embedded field star on the adjacent northern edge.  The nebulosity was surprisingly smooth without a prominent annulus. 

 

I targeted IC 5117 in Cygnus twice, but had not reconned it other than looking up a misleading diameter of 12 arc seconds in the Uranometria Deep Sky Field Guide...uhhh, no, try 2 arc seconds.  I tried high power, I tried filters, but the problem was I didn't know precisely where it should be in the field, or the actual size, and the seeing was very poor both times I tried...bloating stars to about the same dimension.  Upon checking the position more carefully at home, I am certain I saw it, and recognized the asterism that it formed, but I didn't ID it at the time.  I also had some indication of the changing relative brightness with an OIII, but I was so frustrated by worsening seeing conditions that I gave up on it.


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#2 happylimpet

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Posted 03 September 2019 - 03:53 AM

Gosh. You know a star's hot when its known by its ROSAT X-ray designation.


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#3 Keith Rivich

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Posted 03 September 2019 - 11:19 AM

I remember looking at the Methuselah nebula many years ago in west Texas with my 12 1/2" scope. Very diffuse but not to terribly difficult. It is a fainter version of the Medusa nebula (Abell 21). 


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#4 mccarthymark

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Posted 03 September 2019 - 04:54 PM

Red, Awesome observation.  I observed this during the 2018 CalStar also with 20":

 

"MWP 1: 205x.  Exceedingly faint large shell seen with averted vision & OIII filter only; it hangs from a string of stars like a water drop. Brighter on the SW rim, and barely there through the rest of the shape; seems to have ghostly rings inside the shell?  Edges are soft but not diffuse. A small star is green with the OIII but it is not central to the nebulosity and not clear to me it is a central star.  [According to Kent Wallace in his "Visual Observations of Planetary Nebula," it is called the "Methuselah Nebula" due to its age, estimated at 150,000 years, old for a PNe; the shells of most dissipate within 50,000 years.  He also says the first known visual observation of this object was made during 2002 CalStar, probably in the same baseball field I was set up in, also in a 20-inch, and that a certain Jeff Gortatowsky verified the sighting!]"

 

You might also try the nearby Alves 1: 

 

"Alves 1 = ALV1 (PN G079.8-10.2): Very marginal observation.  Large amorphous glow in a scattering of stars, irregular shape, very exceedingly faint -- more felt than seen; maybe seen because I thought something should be there.  205x & OIII only. 

 

Here's an image which shows both of these together 


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#5 Redbetter

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Posted 03 September 2019 - 05:28 PM

Gosh. You know a star's hot when its known by its ROSAT X-ray designation.

 

Yes, that caught my attention as well.  I am trying to understand if the star is still playing a role in ionizing/illuminating the nebula from such great distances, or if all of this is some long afterglow from the initial ejection of the shell and ionization/illumination when it was still close to the star.  I, honestly had not thought much about this before.  But this one and the Veil supernova remnant shell have me thinking more about why they continue to glow so brightly so long after and so far away from the initial source of illumination.  

 

These particular types of stars are interesting critters at this phase, with a possible late, exposed-shell helium flash. 


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#6 azure1961p

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Posted 03 September 2019 - 05:52 PM

7027 is my fav planetary for sheer highsurface brightness. Under a dark sky.it looks positively odd with my 8".

 

Pete


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#7 sgottlieb

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Posted 03 September 2019 - 08:46 PM

Here's an observation of IC 5117 with my 18-inch.  It is a tiny one!

 

Picked up at 175x in a rich star field by blinking with an OIII filter.  Excellent contrast gain using the filter.  Forms the fainter component (V = 11.5) of a "double star" with a mag 10 star 21" ENE, but with the filter the planetary dominates the star.  Interestingly, there is similar double (Es 1339 = 10.8/11.5 at 24") in terms of separation and position angle ~3' NE!   Unfiltered, IC 5117 has a soft, bluish appearance.  Using 450x, a very small 2" disc was clearly visible but it was too small to resolve any structure.


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#8 Redbetter

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Posted 04 September 2019 - 08:23 AM

Third time is the charm.  I was able to detect IC 5117 last night, a wee bugger indeed!  It was right where I thought it had been based on changing relative brightness of stars with and without an OIII filter or a UHC.   I noticed an interesting effect in that the nebula/star looked slightly dimmer than the redder 9.9 mag star following when using the UHC, and slightly brighter with the OIII.  Without any filter the following star was substantially brighter.  Seeing was still in the mediocre/poor category but much better than my prior attempts--yet not even close to good enough to show a first diffraction ring in the 20". 

 

I could tell that the filtered IC 5117 was slightly larger in diameter, but the companion star was bloated enough that this was an insufficient test.  Interestingly, I found that some of the best comparison was at 417x unfiltered.  This showed the deep orange color of the companion star and spurious disk within a shattered/moving diffraction blur, contrasting with the greenish blue tint to the nebula/star.  And the nebula/star appeared to have some diameter compared to the orange companion's spurious disk.  I used powers of 278, 357, 417, 500, and 625x trying to find the best allowed by the seeing.

 

I don't believe the visual portion of this nebula is 2" wide, at least in less than excellent conditions.  I would put it at effectively 1.5" or less.  I found a Hubble image that seems to match this, with the brighter portion of the major axis at perhaps 1.5" and the brighter portion of the minor axis at ~1".  (Note, reading a bit deeper, it looks like the associated paper gives dimensions for the inner shell as 1.68 × 1.16".)   Link.



#9 uwe_glahn

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Posted 05 September 2019 - 11:06 AM

I logged three observation for IC 5117, one with a 16-inch (see the sketch) and two with the 27-inch. All but the last says "stellar".

The last observation was with 1465x, under very good transparency and seeing. I wrote: 1:2 E-W elongated with a knot at the E end; W end more widely; CS is popping in and out of view; CS filter confirms the CS"

sketch: 16", 515x, no filter, NELM 6m5+, Seeing II

IC5117.jpg

 

MWP 1 indeed shows the brightest section to the S. I detected this central section even with my old 16-inch. The arcs were surprisingly easy to me under good but not perfect transparency with the 27-inch. I had the best results with max. EP around 6mm.

sketch: 27", 113x, [OIII], NELM 6m5+, Seeing V

MWP1_27.jpg

 


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#10 Asbytec

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Posted 09 September 2019 - 09:28 AM

Higher power revealed a compact boxy object with partitions into three sections with a bright knot in one (preceding edge) that was so intense as to appear to obscure a bright star.

 

You guys are going at it. This is all I got. smile.gif

 

NGC 7027.jpg


Edited by Asbytec, 09 September 2019 - 09:47 AM.

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#11 Mike Lynch

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Posted 10 September 2019 - 07:10 AM

All,

 

     I have been trying to determine whether the Methuselah Nebula is in the deep sky database of Sky Safari 6+ by another name than the ones I've found in this topic. I've not been able to find it.

 

      Any help, including exact coordinates, would be appreciated. (Sky Safari, incidentally, uses the traditional hours, minutes, and seconds for RA and degrees, minutes, and seconds for Declination, rather than decimal hours and degrees.)

 

Thanks!

 

Mike



#12 JimK

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Posted 10 September 2019 - 10:24 AM

All,

 

     I have been trying to determine whether the Methuselah Nebula is in the deep sky database of Sky Safari 6+ by another name than the ones I've found in this topic. I've not been able to find it.

 

      Any help, including exact coordinates, would be appreciated. (Sky Safari, incidentally, uses the traditional hours, minutes, and seconds for RA and degrees, minutes, and seconds for Declination, rather than decimal hours and degrees.)

 

Thanks!

 

Mike

According to Kent Wallace in "Visual Observing of Planetary Nebulae" (p 337), MWP 1, Methuselah Nebula, is at 21 17 10.3, +34 09 34 (2000.0), is also known as PN G 080.3-10.4, PK 080-10.1, RXJ 2117+34, V 2027 Cyg, and was discovered in 1987 by Alain Maury, and first published by S.D Kawaler & P.N. Appleton (see 1992AAS...181.3902K, with some additional discovery info/images in 1993AJ....106.1973A).


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#13 Mike Lynch

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Posted 10 September 2019 - 10:33 AM

Jim,

 

     Thank you very much!

 

Mike 



#14 Redbetter

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Posted 11 September 2019 - 01:40 AM

Those are the same designations I gave in the opening post subject to the randomness of catalog syntax...  Syntax/spacing can be tricky when searching.  Extra zeroes are sometimes needed, sometimes not, as are additional digits after what would be the decimal at times.  Planetary nebula are particularly bad about this. 



#15 Mike Lynch

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Posted 11 September 2019 - 11:36 AM

... Syntax/spacing can be tricky when searching.  Extra zeroes are sometimes needed, sometimes not, as are additional digits after what would be the decimal at times.  Planetary nebula are particularly bad about this. 

How true!  That's why I tried to make sure I used the exact text / numbers / decimals / spaces when searching for this nebula in Sky Safari....with no results showing up.



#16 Fabrice MORAT

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Posted 03 October 2019 - 07:04 PM

After Uwe G., here is my contribution last week for MWP1 PN with 600mm Dobson and 88/119x power + OIII filter. (La Palma sky, excellent transparency and seeing III, height object = 66°). This drawing is quite deep because i've spent a lot of time to note each star with red light, so my eyes had all the time to be fully dark adapted. But it's possible to find on this sketch some faintest details not well positioned (because of average vision)

MWP1 forum.jpg

MWP 1 détail.jpg

By increasing order of difficulty :

- CS obvious  magv 12,3

- area 1 perceptible in average vision without filter

- area 2 sems mottled NW

- central area 3 like a zigzag milky lane NW

- area 4 as an oval W patch (Note the perception of the external filament, when several glimpses appeared, this detail was not so faint, i have drawn it when in doubt...)

All these delicate fragments have been verified by 5nm OIII filter (88x power) to be sure.

Finally, we have chance to capture visually this very old PN because its dilution into the ISM should have been well involved. At the end, my pastel drawing reminds me a Dumbell (M27) highly shredded with bipolarity clearly recognized. Fabrice M.


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