Helix Nebula

2020-11-10 C63 Helix Nebula NGC7293 Stack_30frames_7187s

Caldwell 63

NGC 7293

Magnitude: +7.6
Apparent size:14.7 x 12.0 arc min (less than half a Moon).
Actual Diameter:3.4 light years.
Distance:790 light years.
Image date:2020-11-10.
Exposure:30 sub-frames @240 seconds = 120 minutes.
Field of View:47.7 x 31.7 arcmin. Up is 169 degrees E of N.

I think planetary nebulae are the most beautiful objects in the sky. They are short-lived marvels of relatively modest size compared to galaxies, globular clusters and most other types of nebula – and there are never two the same. The Helix Nebula is one of the closest and hence one of the largest planetary nebulae. So there was no need to crop this image.

Before there was a nebula, the central star of the Helix was an average sized star which ran out of fuel and – not being large enough to explode in a supernova – it shed its outer layers. The exposed inner core became a white dwarf star, while the released gases were ionised by the ultra-violet radiation from the white dwarf and will expand and fade for perhaps another twenty thousand years before it dissipates completely.


Some further information about NGC 7293 can be found at SIMBAD.

The precursor central hot white dwarf star WD 2226-210 is easily visible at magnitude 13.4, dead in the center of the ring and some further information about it can be found in this paper.


Here’s where the Helix is located, using images generated for me by Astrometry.net:

Helix Nebula in the Celestial Sphere
Helix Nebula in Aquarius

The Sun will eventually also follow the same evolutionary death cycle. If the resulting nebula were to be comparable to the current size of the Helix, it would reach about 85% of the distance to our nearest star, Proxima Centauri.

When that occurs, in about five billion years, all life on Earth will become extinct as the Sun swells into a red giant, becomes a planetary nebula and a white dwarf, before meeting its ultimate fate as a black dwarf.

By Szczureq – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=34794215

Our descendants

will never find out

what a planetary nebula

looks like from the inside.

Will humans still be around at that time to be fried alive by the Sun? Will they even be recognisable as humans? Will some of them escape in a rocket propelled life-ship, to roam Milkdromeda (as it will be then) in search of a rare habitable planet?

They will have due scientific warning of the impending disaster. However, recent history might indicate that political leadership is so often bereft of scientific literacy that it will lack the ability to act responsibly when the crisis looms.

Telescope Details

SkyWatcher Esprit 120 mm apochromatic 3-element refractor; 840 mm f/l @ f/7.
Field flattener; 2x Televue Powermate. ZWO Duo-band Hα (656nm) and OIII (500nm) filter.
SkyWatcher EQ6-R Pro mount; ZWO ASI120 guide camera.
Imaging camera: ZWO ASI 071 MC Pro (CMOS 28.4mm 16 Mpx).
Software: EQMOD, PHD2, SharpCap, Gimp.
Observatory location: 34° South.

Images © Roger Powell


    1. Hi Mark. Yes, the central star is a thirteenth magnitude object and really is dead centre. It’s temperature is around 100,000°K and its UV light is responsible for exciting the gases which make the ring glow at a specific wavelength.

      Liked by 1 person

  1. The camera you are using looks very interesting to me. I have a now vintage SBIG 10-XME which is a monochrome CCD. Processing is not my favorite thing to do and I am wondering about a color cam. I have a modified Canon DSLR but it doesn’t work well with my software. Something maybe about how the CMOS chip makes its Bayer pattern that makes it hard for my system to focus and expose flats. Anyway . . . nice work, keep sharing!

    Liked by 1 person

    1. I went with a colour camera because I do not have enough viewing opportunities to muck around with imaging and processing the same object with several different filters and I did not want the added complication that comes with the monochrome option.

      Colour may have its downside and I’ve seen some brilliant results from those who adopt the monochrome process but one shot colour suits me and I don’t regret it.

      Liked by 1 person

  2. Really nice! Unfortunately up here in the north it is not in a good position being quite low in the sky. However a color sensor might make it worth a shot thus avoiding the whole LRGB thing which will take forever. I am seeing these color CMOS sensors getting better and better and I really think soon the whole monochrome/ filters thing is going to become obsolete!

    Liked by 2 people

    1. Monochrome becoming obsolete? That’s interesting, coming from someone who successfully uses that method! It’s a bit too long-winded for me, I’m happy to be getting my more modest colour images. Who knows where astro-imaging will be in a few years time…..

      Liked by 1 person

    1. I’d guess that too – but despite the inevitable destruction of our atmosphere, resources and probably most of the population, an evolutionary pathway may be found. Maybe survivors will live at the poles or underground.

      Liked by 2 people

    1. They are a great contributor to inter-stellar gas clouds and future star generations, because more stars are destined to become planetary nebula. The really large stars that go supernova are more rare.

      Liked by 1 person

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