Helix Nebula NGC 7293

2021-09-08 NGC 7293 Helix Nebula

Caldwell 63 in Aquarius

Image exposure:
2.5 hours
Image field of view:
83.8 x 55.5 arcmin
Image date:

At seventh magnitude this planetary nebula is only 790 light years away and one of the best of its kind. It’s listed as one of the closest planetary nebulae and is also one of the brightest. Its angular diameter is about half the diameter of the Moon and its physical diameter is 3.4 light years.

The progenitor star which emitted the nebula about 10,000 years ago is still prominent in the centre. It was a red giant star before jettisoning its outer layers of gas – but now only the exposed internal core of the star remains, as a white dwarf.


White dwarfs are an evolutionary stage for stars with insufficient mass to collapse into a neutron star or black hole. The stages of evolution are:

Low mass star > Red giant star > Planetary Nebula > White dwarf star > Black dwarf.

The planetary nebula stage is the shortest, lasting typically only about ten to twenty thousand years.

The remnant core will spend the rest of its starry life as a white dwarf star, slowly cooling over perhaps trillions of years to become a cold black dwarf in the far distant future. None are believed to exist yet, as the Universe is not old enough.

It is the energetic radiation from the white dwarf star which is causing the ejecta to fluoresce.


Thanks for reading!

Cosmic Focus Observatory

34° S

Above us only sky….

Telescope:SkyWatcher Esprit 120 mm apochromatic refractor; 840 mm f/l @ f/7.
Optics:Field flattener; Astronomik light pollution filter.
Mount & Guiding:SkyWatcher EQ6-R Pro mount.
Imaging camera:ZWO ASI 071 MC cooled.

Images © Roger Powell
I’m one of the founder members of Macarthur Astronomical Society


    1. Yes, that’s why the number of planetary nebulae is limited. They’re just exotic expanding rings of gas and dust which eventually disperse into the inter-stellar medium.

      Liked by 1 person

  1. I was out two nights ago enjoying our recent string of clear nights. I caught a view of a similar nebula M57 just before it went behind the edge of the roofline. My view was much less vivid than yours. Before quitting, I looked at Alberio and its companion. Always a colorful view.


    1. The first time I saw the Ring Nebula through the eyepiece was one of those “wow” moments I won’t forget – a bit like seeing Saturn’s rings for the first time.

      Albireo is beautiful through the eyepiece too. I understand there is doubt whether it is a true binary or an optical double.

      I really should try imaging a few more double stars….


      1. The trouble with Albireo is that it is nearly straight up for me this time of year. It is hard to get positioned to look through the eyepiece. I guess I need to get a camera eyepiece and view on the computer. 🙂

        Liked by 1 person

        1. While you’re lying on the ground with your head cocked at an awkward angle and someone tripping over your legs, you can take solace in the fact that you are getting the best viewing experience of Albireo through the minimum amount of turbulent atmosphere….

          Liked by 1 person

    1. Maybe some similarities but what I like about planetary nebulae is that they are each unique. Unfortunately the majority of them are very distant and consequently appear very small. 🙂

      Liked by 1 person

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