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Observation by Ian Smith: Planetary Nebula Abell 16

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Ian Smith


Ian Smith


2021 Feb 17 - 00:00


2021 Apr 04 - 15:26


Abell 16

Planetarium overlay



Field centre

RA: 06h43m
Dec: +61°47'
Position angle: -92°01'

Field size

0°14' × 0°09'

  • Celestron Edge HD11 telescope
  • QSI6120 CCD camera, binned 2x2
  • Guided by ONAG and Ultrastar

Ha: 30x1200s; O3: 30x1200s; N2: 30x1200s



Target name

Abell 16


Planetary Nebula Abell 16

About this image

This is my attempt at Abell 16,  a faint planetary nebula in the constellation of Lynx.

In this image north is to the right and east is to the bottom. For the nebula, the narrow band channels have been blended according to the following scheme:

Red = 0.9*Ha+0.1*N2, Green = 0.5*(Red + O3), Blue = O3.

The background stars are 30x60s each in red, green and blue.


Abell 16 is one of the few examples of spherical PNe. Unfortunately, it is very faint and so is rarely imaged and doesn’t show up much in the professional literature. I found one study on the deceleration of nebula shells that talks about it, but otherwise it tends to show up in various surveys. From these we can glean the distance of (2413 lightyears), a diameter of ~3 lightyears and gas expansion speeds of ~37km/s.


PNe are the result of a slowly expanding shell of gas ejected by the progenitor star in its AGB phase, interacting with the faster stellar wind given off when the progenitor star’s core is exposed. Often these winds are shaped by magnetic fields, companion stars, the interstellar medium and other effects, but in this case the gases appeared to have expanded equally in all directions.

Given that this interaction results in the turbulent mixing of bubbles of hot gas, I have deliberately highlighted the layers containing structures with a size similar to the FHWM of the image to give the impression of a roiling, boiling sphere of expanding gasses.

Files associated with this observation
Like this image
Martina McGovern
Martina McGovern, 2021 Apr 04 - 17:22 UTC

Wow, amazing image, well done.

Grant Privett
Grant Privett, 2021 Apr 04 - 22:19 UTC

I would second Martina. Love the fine detail....

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