Planetary Nebula IC 418
|Apparent magnitude: +9.3|
|Apparent dimensions: 0.2 arc-minutes|
|Image exposure: |
|Image date: |
It’s been a cloudy summer here so far, with plenty of rain and Sydney’s long-term weather forecast still looks something like this:
☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁ ☁
I managed one solitary imaging session a week ago and my targets were two planetary nebulae & the galaxy M77. Unfortunately, the galaxy was ruined by cloud and so this is the last image I’ll be posting until the weather clears up – unless there is a decent evening electrical storm to shoot.
IC 418 is interesting because of its colourful hues, which are unlike my other recently posted planetary nebulae images, most of which have been a cyan appearance. Confusingly, three of my reference books describe IC418 as “greenish-white”; “bright bluish disc”; “a nice reddish oval disc with a bright bluish central star”.
The white blob at the centre of my image could conceivably be the central star but I think it also possible that it could be a bright condensation of gas, over-exposed in my image and masking the star itself. Because of the short exposures (30 x 10 sec), no other star was visible in my image to use in comparison.
The major components of the nebula were described as ionised oxygen and hydrogen. The distance is estimated to be 3,400 light years and the diameter about 0.2 light year.
IC 418 is known as the Spirograph Nebula, because the intricate patterns which can be seen on images taken by the Hubble Space Telescope look similar to the patterns produced by a spirograph. (I wish I had one of those things to play with when I was a kid).
Well, the Webb Telescope has now taken up residence at Lagrange Point 2, 1.5 million kilometres from Earth and we eagerly await the completion of mirror and instrument commissioning, followed by the first images in a few months time.
However, the big news in astronomy this week has been the discovery of a black hole which has no accretion disc or any other object associated with it. You can’t see a black hole on its own, so how on Earth did they discover it?
The astounding answer is that it was passing in front of a background star which was then magnified by the distorted gravitational field of the black hole!
The discoverers refer to this high-magnification microlensing event as: MOA-2011-BLG-191/OGLE-2011-BLG-0462 and it’s in the direction of the Galactic bulge. This exquisite science is reported in their Arxiv paper .
Images © Roger Powell
|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.|
Cosmic Focus Observatory
Above us only sky….
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