Planetary nebulae, EEVA-style

[Bill S]

K 1-20 is a pretty faint ghostly object to manage to catch.

I looked it up in Kent Wallace's Visual Observations of Planetary Nebulae. The entry says that it was discovered by Lubos Kohoutek and reported by him in 1963. It was found on the Palomar sky survey prints. Wallace reports seeing it with a 20 inch reflector requiring an OIII filter and averted vision and says it was first seen visually by Jack Marlin using a 17.5 inch in 1985.

It is also known as ARO 384.

Bill

 

[Martin Meredith]

Here's a dozen PNs I observed in the northern skies over the last two nights, mainly but not always before the moon came up (I was blaming Bilbao's light pollution halo until I realised what was the actual culprit...)

The sizes are quite varied, randing from 5 arcsecs to 5.7 arcmin. These all taken using the 8" f4 Quattro, Lodestar X2 mono and Baader LRGB filters, live combined, with roughly equal numbers of subs in each filter. More details below. No calibration frames used. Saturation has been turned up high for most of these. 

IC 5217 6.6" Lac 2m40 (32x5s) -- tiny but intense
HU 1-1 5.0" Cas 2m40 (32x5s) -- mnauve/grey, featureless but then again, occupies only 2.5 of my pixels
BV 5-1 18" Cas 3m45 (45x5s) -- what a strange object!
Simeiz 22 5.67' Cas 9m45 (39x15s) -- brighter than I imagined; beautiful crescent
NGC 7139 1.28' Cep 5m25s (65x5s) -- blood orange slice
NGC 6058 23" Her 5m20 (64x5s) -- electric
NGC 7354 23" Cep 5m20 (64x5s) -- lots of structure/colour
NGC 40 48" Cep 4m25 (53x5s) -- had to turn saturation *down*
M76 1.12' Per 4m10 (50x5s) -- red apple core with electric blue
IC 1747 13" Cas 4m30 (54x5s) -- incomplete doughnut
IC 289 35" Cas 7m15 (29x15s) -- subtle, interesting structure
EGB 1 4.5' Cas 7m45 (31x15s) -- there is something there (pale red) but not obvious, although a blue star is visible which is likely to be the central star

 

Simeiz 22 is well worth a look in mono too. It needs a huge stretch but the double stranded structure is clear.

 

Now I'm off to see what I can find out about BV 5-1....

Cheers

Martin

 

 

 

[Martin Meredith]

BV 5-1 is more easily found as either ARO 199 or BV 1

BV stands for Böhm-Vitense whose 1956 discovery paper is available [1], although no real details of BV 5-1 are provided as far as I can see. A more recent article [2] suggests that what we're seeing in optical images is the equatorial line, perpendicular to the axis of symmetry of the PN (my understanding is that it is edge-on to our line of sight). There are some good optical images in the paper by James Kaler and colleagues [3]

This view provides more idea of scale and context (and weirdness) .. and tracking errors maybe too.

[1] http://articles.adsabs.harvard.edu/pdf/1956PASP...68..430B

[2] https://www.aanda.org/articles/aa/pdf/2001/35/aah2956.pdf

[3] http://articles.adsabs.harvard.edu/pdf/1988AJ.....96.1407K

[Marvin Jenkins]

This whole thread is mind blowing. I can’t quite believe how deep space this is going. 
Just when I start getting my head around Barnard objects and all the others, this happens😱

Marv

[Mr Spock]

I don't understand this EEVA stuff but can't help but be impressed by the targets being captured. Gives you something to think about.

[Marvin Jenkins]

I think I understand it, just taken aback by what is being captured.

Definitely not in the realm of being able to do EEVA but right now I am happy to to do visual Astro.

I am happy to see there is another dimension that astro is pushing into, and that is definitely the EEVA dimension.

I will one day day be part of this so already a convert. Next clear night I will see what I can do in a limited way.

Marv

[Mike JW]

Hi Martin,

Wonderful set of captures. If I was certain my scope could reach focus with a filter wheel, I would order the gear immediately.

Mike

[Martin Meredith]

Hi Mike

Thanks. With PNs you never really know what you're going to get if, like me, you avoid looking them up beforehand...

Do you currently use an extender? I need to use one if I don't use the filterwheel, Replacing it with the filter wheel gives me a similar focal distance. Your Ultrastar will slide in until it almost touches the filters so the critical distance is to the back plane of the filters, plus a little extra.

Martin

 

[Mike JW]

Simeiz 22 (Sh 2 -188) is an intriguing object. Why just an arc?, why filaments?.

See Sh2-188 Nebula (iac.es)  for the full picture. Sure enough there is more going on than just an arc.

See 901405.pdf;sequence=1 (herts.ac.uk) for a model of how its structure has come about. Briefly put the model suggestion a triple wind hypothesis.  Initially there was the Asymptotic Giant Branch (AGM) wind. This is the slow solar wind that a star in the giant red stage is sending out. It would appear that this wind as it slammed into the Inter Stella Medium caused the bright arc (and tail) that we see. At this stage a PN had not formed. Next as the star collapsed the fast stellar wind blasted outward forming a ring structure (see the first link) as the two winds interacted. However the star is moving quite fast through the  inter stella medium (ISM) - 125+/-Kms towards the bright arc and this third wind along with the other two winds has given rise to the observed structure.  The bright arc is a result of the high velocity of the central star in the direction of this bright arc. The star is displaced from the geometric centre and its high velocity causing thin shock compressed  filaments concentric to the bright arc. Sh 2-188 is one of the largest PN known, about 8.5 lyrs across.

Mike

 

 

Edited October 29, 2021 by Mike JW

[Martin Meredith]

That's a great capture. Aperture really helps when it comes to faint nebulosity. Now I can make out 3 strands. The back story is fascinating. I recalled that PNs are capable of multiple ejections but the idea of slower processes such as you describe is a new one to me. I wonder if the Helix is also the product of such a process.

Martin

[Mike JW]

EGB -1. I have struggled to find any info on this one, other than it is about 2000lyrs away.

IC 1747 . The CS is mag 15.8. My shot hints at that dark region around the CS.  The thick outer ring has two much brighter sections - bi-polar. Outside of the thick ring I have just started to pick up a fainter fringe. I certainly did not expect to pick up the dark 'spokes' (x 3).

BV 5-1

and here is another BV in Cassiopeia 

BV 5-2 - another weird PN. Nice image - Böhm-Vitense 5-2 (BV 5-2, Sh 2-179) PN G121.6+00.0 photo - jshuder photos at pbase.com

Mike

[Martin Meredith]

Here's one from my last session (in October). At first I thought I was looking at a double star rather than a planetary nebula:

but as stacking progressed I could see that this appeared non-stellar, but at the same time not like any other PN I'd observed.

This is in fact a proto-planetary nebula known as the Egg Nebula. Although it appears to be made up of two starlike entities, the object is a single F5 type star that is surrounded by a dense layer of dust/gas; the two bright spots are actually unresolved (in my case) beams of light that have penetrated the thinner regions of the dust (see https://en.wikipedia.org/wiki/Egg_Nebula for more on this). You can just make out these narrowly-divergent beams at the ends of the PPN in my shot but someone with a higher resolution setup ought to be able to get a better view -- I am right at the pixel limit here.

Martin

 

[Mike JW]

Fascinating observation and web link. I will put it onto my list but fear with this on going poor weather I will have to wait until Cygnus reappears in the east.

Mike

[Martin Meredith]

Sorry to be posting Cygnus observations in late December -- a long wait for the next opportunity!

Here's another one from the same session. Outside the Messier/NGC/IC catalogues one might expect to see relatively faint PNs, but M 1-79, discovered by Minkowski in 1946 (aka ARO 365/VV 268) is an exception, with a published surface brightness of 20.6. It is also a very colourful object just over half an arcmin across, and categorised as an 'elliptical PN with internal structure'.

It sits in a relatively dense region of Cygnus in the Lacerta direction. Annotations (not shown) of some of the brighter stars suggests that it lies (visually) within with the very large open cluster NGC 7092 (which is over 2 degrees across and cannot be appreciated in this image).  Paper [1] gives a distance to the PN of 2.7 +/- 0.9 kpc which is about 10 times further out than the open cluster. I mention distances because they are notoriously hard to obtain for PNs -- table 3 of [1] gives an indication of the wide spread of estimates for M 1-79 (one of which is sufficiently low to place it within the open cluster).

 

 

 

I haven't observed many from the Minkoswki catalogue(s) but I'm running out of NGC/IC PNs and since the Abells are so faint I imagine I'll be seeking out more 'M' PNs in the future.

Martin

 

[1] 

[Martin Meredith]

Here's another from that last session. This is NGC 6765, also known as M 1-68 from the Minkowski catalogue. This one is conical and blue with a mauve base.

 

The SDSS image is fascinating and shows 3 whorls surrounding the base. Two of them are visible in my image (faint greyish disks below and to the left of the base of the PN; the third is just about there if you know where to look to the right). There is a discussion of this PN here:

https://www.cloudynights.com/topic/500597-the-other-pne-in-lyra-ngc-6765/

In fact, there are several more PNs in Lyra besides this and M57. I'll post a couple below.

Martin

 

 

[Martin Meredith]

This one is surely the other ring nebula in Lyra!

I always look for M57 by pointing towards the midpoint of the 'lower' (southern) side of the parallelogram of 4 stars making up part of Lyra. If instead you were to look at midpoint of the 'right' (eastern) side of the parallelogram, you'd find M1-64, another member of the Minkowski catalogue (use "pn M 1-64" to find it on Simbad/Aladin), easily spotted with a mag 14.9 stellar 'jewel' set in the ring to the N. This has a surface brightness of 18.8, sufficiently bright to everexpose the DSS image wash out all trace of colour. As a comparison, at just 18 arcsecs across this is about one fifth the apparent size of M57 (whose surface brightness however is 20.3).

 

[Martin Meredith]

... And even a 3rd 'ring' in Lyra. It is hard to be sure in this case but the DSS image shows the annular form well. This is K 3-27, a small grey smudge about 16 arcsec across, with a mag 18.3 central star (visible here outshining the nebula). The PN is challenging to spot in the full image. In the zoom there is a hint of a split (or two) in the ring. Try as I might I couldn't squeeze more than a slight tint of purple/blue out of this one.

There are a couple of other (known) PNs in Lyra including SP 4-1 -- a tiny blue dot -- and Abell 46 which is very faint (though shows up as a dense crescent in H-alpha) and has a beautiful bright blue central star.

Martin

[Mike JW]

Hi Martin,

Great to see these guys in colour. Makes the viewing so much more interesting.

Here is my NGC 6765, which adds nothing to your view - colour wins.

Mike

 

[Mike JW]

Abell 20 and 24 in CMi provide a couple of interesting PN challenges.

Abell 20 has a very blue CS and an evenly bright ring. Martin/Bill and others would make for a great colour shot. Also known as PK214+07.1

 

Abell 24 is 1730 lyrs away and shows up well  in Ha (another good one for the colour set ups)

Mike

 

 

[Martin Meredith]

I like the look of these and will certainly give them a go. I'm guessing you weren't using an Halpha filter?

Abell 24 looks too diffuse for me to pick up much based on previous attempts -- will be a good test for the new cam though.

Martin

 

 

[Mike JW]

Hi Martin,

Looking forward to see how you get on with visiting these two PNs. (No filters for me. My comments were based on images on the Web).

Mike

[Martin Meredith]

I might give them a go tonight in spite of the near-full moon (crazy, but intriguing to see what can be done, and clear nights are not too frequent here). Canis Ma/Mi, Monoceros and Puppis are some of my favourite regions. 

Actually, I did look at a couple of PNs last night, not too far from the moon, and was surprised yet again at what is possible.

This is NGC 2022, an object I was inspired to look at by Callum/BAA as the 'PN of the Year'. I stretched it a little more than I normally would to bring out the outer shell. The bright inner shell ring has two bright spots diametrically-opposed, one slightly dimmer than the other. I did wonder if one was simply a background star seen thru the PN but Hubble images confirm that these are part of the shell. Other images show the 'ring' to be two slightly offset semi-circles. I'd like to revisit this with no moon to see how much difference it makes.

 

I also looked at NGC 1535 in Eridanus, looking rather solitary in a sparse scattering of stars. This is a fascinating object to view, in some ways comparable with NGC 2022 in the sense of having a ring and shell, but somehow better-defined. The outer shell in particular is remarkably smooth with a fairly clear boundary. In high resolution pictures the halo is not quite so smooth but has a filamentary structure. The inner region shows plenty of detail too, like a cut lemon slice. I'm guessing in this case the stellar object visible in the outer shell is a background star.

Martin 

 

[Mike JW]

Great results and as always it makes want to rush out and buy the colour kit (which I will not be doing!).

Mike

[Martin Meredith]

This is NGC 246 in Cetus (also known as the Skull) not far from its transit at around 33 degrees, again under a near-full moon.This is a rather large object as PNs go and yet still reasonably bright, at least around part of the expanding edge. This one I have to revisit under moonless conditions.

One feature that struck me as I was observing was that the central star appears (optically) double. I thought at first that this was a tracking issue but as the colour built up the colour distinction became clear, and checking other images indeed there is another star right next to the blue central star (a mag 11.8 white dwarf).

10s exposures, gain 100, bin 2.

Martin

Edited January 16, 2022 by Martin Meredith

[Mike JW]

Doing well to spot the pair of stars in the centre and get the colour difference.

Mike