M27 The Dumbbell Nebula in bi-colour

[steppenwolf]

Messier 27 - The Dumbbell Nebula

M27 is a classic and very popular planetary nebula in the constellation of Vulpecula. Through the eyepiece of a small telescope, M27 takes on the appearance of a ‘dumbbell’ or ‘apple core’ giving it its common name but photographically, the nebula takes on a very different shape, an ellipse at right angles to the more prominent core. A DSLR camera will easily capture this additional detail and deep exposures using a CCD camera will start to show the faint halo surrounding the main nebula. Narrowband images allow a wide range of false colour interpretations to be explored and this is what I am showing here.

Discovered in 1764, the true nature of the object was yet to be determined with the misnomer of ‘planetary’ being ascribed to William Herschel in whose telescope the objects appeared similar to planets because of their generally circular shape. This type of nebula lasts for a few tens of thousands of years which makes them a short-lived phenomenon in cosmic terms. Towards the end of a star’s life, the ‘Red Giant’ phase, the star’s outer layers are pushed outwards by powerful stellar winds. Once the majority of the star’s atmosphere has been lost, the hot luminous core emits ultra-violet radiation which ionizes the star’s outer layers previously dispelled, causing them to glow. Rich in Hydrogen Alpha (Ha) and doubly ionised Oxygen (OIII) and to a lesser but sometimes still significant amount, singly ionised Sulphur (SII), singly ionised Nitrogen (NII) and Hydrogen Beta (HB), these nebula respond very well to narrowband filtering.

This image was captured in just Ha and OIII with the Ha being mapped to the red channel and the OIII being mapped to both the green and blue channels. Mapped in this manner, red and blue colours similar to those produced by broadband imaging can be achieved but with the additional fine detail and contrast that narrowband imaging can produce. The Ha data was collected during Moonlight conditions and the OIII just after the Moon had set. I need more data to complete this one but I was especially pleased to see the halo in this preliminary version.

Image Stats

Mount: Mesu 200
Telescope: Sky-Watcher Esprit 150 ED Pro
CCD Camera: QSI 683 WSG-8
Sampling: 1.04”/pixel
Guiding: OAG/LodeStar
Filters: Astrodon 3nm Ha and 3nm OIII
Exposure: 23 x 1800 sec Ha, 13 x 1800 sec OIII
Date: 24/07/17 - 28/08/17 – much of which was under Lunar illumination
Calibration: Bias, Darks & Flats

Object Stats

RA: 19° 59’ 36.0”
Dec: 22° 45’ 57.0”
Magnitude: +7.3
Distance: 1360 light years

The Individual Ha and OIII Data

The Ha/OIII Image

[Uplooker]

Super image Steve. The outer shell is looking fantastic!

[triton1]

Stunning love the colours and the amount of extra detail.

[Mick J]

Outrageously good, I make that 18 hours so far - be interested to see where more data takes you.

[gnomus]

Stunning image Steve.  That shell around the nebula with the alternating blue and red colours is especially nice.  

[steppenwolf]

Thanks for your comments, folks.

[steppenwolf]

On 29/08/2017 at 23:31, gnomus said:

That shell around the nebula with the alternating blue and red colours is especially nice.  

I'm wondering how deep I will need to go to get halo data on the left side to complete the circle! It must be very faint indeed.

[toxic]

6 hours ago, steppenwolf said:

I'm wondering how deep I will need to go to get halo data on the left side to complete the circle! It must be very faint indeed.

awesome Dumbbell Steve . you already have a bit showing on the left 

[MartinB]

Lovely image Steve.  Good job on keeping the core detail whilst hammering the histogram to pull out the halo.

[steppenwolf]

Thanks, Martin, this was an 'interesting' object to process and I tried all sorts of tricks including inverse layer masking to pull out the dim detail in that pesky halo!

[MarsG76]

Fantastic work and result... the image looks very crisp with the fan of the outer edge.

 

[swag72]

This is a real beaut Steve ?

[steppenwolf]

21 hours ago, toxic said:

awesome Dumbbell Steve . you already have a bit showing on the left 

Thanks, Chris, yes here is a smidgen there but there's more to come from that side I feel!

[johnrt]

Great stuff Steve, this isn't as easy as you've made it look here!

[steppenwolf]

5 hours ago, swag72 said:

This is a real beaut Steve ?

Thanks, Sara, filters and optics in harmony!

3 hours ago, johnrt said:

Great stuff Steve, this isn't as easy as you've made it look here!

Thanks John, I'm pleased you have enjoyed it.

[Velvet]

Very nice there   Love it  

[steppenwolf]

Thanks, Velvet!

[steppenwolf]

The forecast clear sky last night didn't happen for me so I spent some time working on the outer halo using the original data. I was puzzled by the OIII portion not showing particularly well in the top left portion of the finished composite even though there was clearly some data in the raw image. This was more an experiment than a route to the finished image but it was interesting just how much more of the halo has been released. Nothing has been 'added' to this image, what you see is additional detail released from the original data but I have thrown a whole load of layering tricks at it.

BUT, is it an improvement or just an example of over-processing to extreme?

[alexbb]

Hello, Steve! I really liked a lot the mono images and I felt that the combination didn't show the outer halo enough. On the last image, I'd say it's an improvement, though I wouldn't push the Ha that much. But that's only my preference.

Clear skies!

[gorann]

I love them all four! Why not try a 50:50 blend of the two bi-colour versions? (or use layer masks and the brush tool and use the best parts out of each version)

[gnomus]

There is clearly more detail in the latest version.  I would prefer V2 with the colours of V1....  Sorry!

[steppenwolf]

59 minutes ago, moise212 said:

On the last image, I'd say it's an improvement, though I wouldn't push the Ha that much. But that's only my preference.

Neither would I normally push it that hard either - I prefer the raw data to speak for me!

44 minutes ago, gorann said:

I love them all four! Why not try a 50:50 blend of the two bi-colour versions? (or use layer masks and the brush tool and use the best parts out of each version)

In essence, that is what I have done here but to get the halo to show this strongly required a more red/green palette.

39 minutes ago, gnomus said:

There is clearly more detail in the latest version.  I would prefer V2 with the colours of V1....  Sorry!

Yup, I much prefer the colours in V1 too (which, of course is why I posted it in that colour in the first place) but it was interesting that the halo remained much more subtle in that one.

[Mick J]

26 minutes ago, gnomus said:

There is clearly more detail in the latest version.  I would prefer V2 with the colours of V1....  Sorry!

Agree, I was looking at a few M27's yesterday and so much red & blue in a lot of them. I like these a lot, supple colours in both. More data may help as you are suggesting, I hope we shall see, are the 3nm filters limiting anything ? just a thought  

freak-out-version love it.

  

[Rodd]

Nice

[steppenwolf]

1 hour ago, Mick J said:

are the 3nm filters limiting anything ? just a thought  

They will be cutting NII from the planetary core for certain but perhaps not from the halo.

1 hour ago, Mick J said:

freak-out-version love it

Well spotted!