PN NGC7094's central star

[Clear Skies]

Hi all,

Early this morning I observed the planetary nebula NGC7094 in the constellation of Pegasus. A faint, round glow in my 12" SCT. Nothing spectacular.
What was worth noting, is the nebula's central star. Most if not all stars react to UHC, and especially OIII filters by dimming visually. Stellar PN's can often be teased out by "blinking"; alternating between a filtered and unfiltered view, to see which "star" remains visible, thereby revealing itself as the nebula.

The central star of NGC7094 appears to be an exception. It remained easily visible when filtered, either by an OIII or a UHC filter. I suspect this may be due to a shell of nebulosity surrounding the actual central star. If so, such a shell may be the cause of the central star remaining easily visible when filtered.

Anyone else noticed this effect?

This link (http://iopscience.iop.org/0004-637X/542/2/957/fulltext/51173.text.html) has some scientific info on NGC7094's central star.

Cheers,


Victor

[Ivan Maly]

I saw the central star in NGC 6543 as having a pretty vivid "planetary" color at a very high magnification (>1000x) in the same scope as yours, without a filter. Probably the same effect. Apart from the physical close, highly ionized shell, the star lifting the foreground nebulosity above the scotopic level comes to mind as a possibility.

[Marko]

A very bright central star shows generally using an NPB filter because it may drop a few mags but have plenty of 'suds' left to be seen in a 12" scope.

I have only one logged observation of Ngc7094 and claim the central star in my 18" dob BUT this was 5 years ago and I am afraid I was not specific enough to say the central star was seen with NPB which I sometimes do comment upon.

This is a nice one to re-observe given your thoughts. It would also be interesting to see if any mottled appearance can be detected in the dimmer central area of the shell away from the edges.

[skyraider]

Victor,

I absolutely noticed the same effect with this PN, as I saw NO dimming of it's central star when I used my Orion Ultra Block Filter. I did however notice that the other star that was inside the ring, did dim when the filter was in place. So there is definitely something unique about the central star in this nebula.

Marko,

I did not detect any "inner" nebulocity with or without a filter.

Below are my observing notes:

Spruce Knob, WV
Sept 26, 2014
11:31 PM EDT
Above average seeing
Above average transparency

25" f4 Obsession
TeleVue Ethos 10mm X1.15, 296x,

The Central Star is obvious and there is a second star that sits just inside band that is quite noticable. The nebula itself is a faint uncomplete ring. The diameter is quite large and the "ring band" is narrow when compared to M57. There is an asterism of stars that sits just above it that resembles an A-10 Fighter Jet. The galaxy PGC 67044 is fairly obvious as well.
With Orion Ultra Block Filter
The nebula becomes very obvious, and is a complete ring on occasion. The central star is STILL VERY obvious, but the second inner star becomes occasional. Again, compared to M57 the ring band is narrow in width and large in diameter. No "inner" nebulosity seen.

[Marko]

Ok. I had forgotten to look for this last new moon and due to other situations will not be able to check this time (now) but if you could not see mottling in a 25" it is not likely I would see it so thanks for the note.
As I did not post earlier my actual only observation I do it now 'for the record'. I call the other star out as 'north of center' but I was a bit off as it is really north-east. PA can be a tough thing is what I have found from 'the real world'.
This note reminds me of that CalStar which was one of the very best skies I have ever seen at that site. This year was a bit off from 2009.

Peg NGC 7094 Plan 21 36 53.0 +12 47 19 mag 13.6
Date: 09/20/09 Time: - Site: CalStarLSA
Scope: 18SmF3.7Pc Eyepiece: 7mmNag Power: 278.0x
NELM: 6.9 SQM: 21.44 Seeing: 5 Transparency: 5
'BestOfPlanitaries: 2' dia dia NPB filter. Clear central star. Irregular relief and outer shell. FS N of central star by lt 1' still inside the glow.'