Abell 85 is a fascinating supernova remnant in the Cassiopeia constellation. It is a very dim object with an angular size that is about the same as the full moon. That is to say that if you could see it with your eyes, it would be as large as a full moon in the sky.
I chose this difficult target simply because I find it visually appealing and I love the challenge. As is often the case, after the fact when I research what an object actually is I am blown away with what I learn.
In this case, Abell 85 was formed about 10,000 years ago when a super massive star exploded in a supernova event. It was not discovered until 1955 by George Abell and was added Abell's catalogue of planetary nebulae because, well it was thought to be a planetary nebula. However by 1960 it had appeared in an early radio telescope survey conducted by Caltech. It was not until further research in the late 1960s that it was confirmed that it was in fact a supernova remnant and was classified as CTB1 (Caltech Observatory list B catalogue of radio sources).
Now it gets interesting. Continued observations provided discrepant conclusions about the source of the radio emissions and in particular why the emissions extended out of the NE side. It was not until 2017 that the presence of a pulsar was confirmed by a citizen scientist which was dubbed J0002. Pulsars are super dense, rapidly spinning neutron stars left behind when a massive star explodes. J0002 was discovered to be about 53 light years
outside of the bubble to the NE (roughly the 10:30 position in my image and not visible as these are radio not light emissions). It is thought that perhaps due to an uneven explosion, the neutron star was blasted away from the central point and is currently streaming through space like a cannonball at whopping 2.5 million miles per hour! That is five times faster than the average pulsar travels. There is a 13 light year-long tail streaming from behind the pulsar that points directly to the center of Abell 85 which is clear evidence that this was the likely original source.
Why is the balloon popped? I could not find a clear theory on why. It definitely is not directly related to pulsar J0002 which left the bubble at a different position. The visible emissions that we can see are caused by the remnants of the explosion expanding away from the central point. The leading edge of the bubble itself is expanding more freely with less resistance on the NE side (10:30) due to a density gradient in the interstellar gasses in that direction. It is possible that internal shock waves caused by this pressure gradient blew out the bubble on a weaker front. But that is just my own conclusion.
Although the blue oxygen emissions are concentrated on the western periphery, there is considered to be an abundance of oxygen and neon within the system. This suggests that this was a core-collapse supernova of a star between 10 and 70 solar masses.
This image was captured over many nights to fill time around other projects. Conditions were fantastic at SRO over the period which helped with the resolution on this very difficult to image target. It is a simple HOO pallet with RGB stars added. This is part of a large data backlog that I am working through which built up over the past months while I was traveling for business and vacation.
Interestingly, the colloquial and now popular name "Garlic Nebula" may well have been coined by an Astrobin user @goofi who first used it here in 2015
https://www.astrobin.com/208841/C/?q=garlic&camera=Note: Had I known all of this ahead of time, I would have framed it with north up to make the visualization of the features easier. Also it is entirely possible that I have misinterpreted some of the scientific documentation, and I welcome any corrections from the more enlightened pros.
CS
References:
https://www.nasa.gov/universe/nasas-fermi-satellite-clocks-cannonball-pulsar-speeding-through-space/https://academic.oup.com/mnras/article/527/1/803/7333979https://iopscience.iop.org/article/10.1088/0004-6256/140/6/1787
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