Retina Nebula

IC 4406

A Unique Planetary Nebula in Lupus

Image exposure:
60 minutes
Image field of view:
7.98 x 7.98 arcmin
Image date:

Planetary nebulae are the signatures which represent the transition of an elderly mid-mass star* into a white dwarf. When the mid-mass star runs out of hydrogen fuel in its core, it swells up into a red giant, then puffs off its outer layers, revealing the high temperature core of the star.

The gas which is ejected forms a nebula which becomes ionised by the intense ultra-violet radiation emitted by the exposed hot core, now a white dwarf.

Because it no longer has any ability to generate nuclear fusion, the white dwarf will slowly cool over many billions of years and eventually become a black dwarf. Interestingly, the Universe is not yet old enough to be populated with any black dwarfs.

In planetary nebulae, the white dwarfs will normally reside at the centre, while the nebula expands away from it at high speed, dissipating into the inter-stellar medium – a process which lasts for only a few tens of thousand years.

*Our Sun is a middle-aged mid-mass star.

The nebula of IC 4406 is believed to be toroidal in shape, like a donut seen edge on. The white dwarf is not visible in my image but it does exist.

The Retina Nebula looks unique, as I don’t think there is another quite like it.

Yes, I know it looks more like a tv monitor than than an eye retina. Maybe it even looks like the roof of a car – but nobody would be so vain and so irresponsible to launch a motor vehicle into space, would they. . . . 😶

Astronomy News

In other astronomy news, the James Webb Space Telescope, launched on 25th December 2021, is nearing the end of its commissioning phase and is already working on its first science projects.

The first image is due to be released on 12th July. I am curious to know which astronomical object has been selected for the first image and what other delights will be released in the future as the science ramps up.


Telescope:Meade LX-90 200mm Schmidt-Cassegrain
(deforked); 2000 mm f/l @ f/10.
Optics:Astronomik light pollution filter.
Mount & Guiding:SkyWatcher EQ6-R Pro mount.
Imaging camera:ZWO ASI 071 MC cooled.

Images © Roger Powell

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  1. It looks like spandex stretched too much . . . very unique if one isn’t a regular at a gym or shops at Wal-Mart.

    By the way, did you read about the micro-meteor that struck one of the JWT’s mirrors? Last I heard, they think it won’t be a detriment to the function.

    Liked by 1 person

    1. That’s right, they knew they were always going to get hit by tiny space rocks. They say that it will not affect the images but gave no further reasoning.

      I wonder if they might use calibration techniques similar in principle to the darks and flats that amateur astronomers use to remove noisy pixels and dust specks in the image train. Or dithering methods. Or maybe the damage won’t show up because the dish segments are not at focal level.

      You can probably tell I don’t know much about infrared astronomy technology. . .



      1. The comment they made was that it was larger than what they had assumed might hit the mirrors and had designed for. But, yes, they said technical wizzardy would compensate.

        What I didn’t read is how they know the size of what hit.

        Liked by 1 person

          1. I can buy the interference hypothesis; a seismometer would only tell them the energy of the impact, not the size… unless they also know both speed and angle of approach.

            Anyway, collisions are apparently rare (there’s a whole lot of nothing up there) so this was just bad luck so early in the program. Still, they say they can compensate, so that’s good.

            Liked by 1 person

  2. “Interestingly, the Universe is not yet old enough to be populated with any black dwarfs.”

    Interesting indeed, never realized that. It demonstrates how YOUNG the Universe actually is relative to its own life expectancy.

    Liked by 1 person

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