This is a fascinating area. We are seeing Puppis A, a 3700 year old Supernova, through the Vela Supernova remnant from 11,000 years ago. At 800 ly away Vela covers 10 degrees of the sky while Puppis A, at 7000 ly distant, covers a little less than 1 degree. That’s still too big for my FOV so we are only looking at a section of it. Most of the SNR is seen only in X-ray and this image from BBC Sky at Night helps put things in perspective:

https://www.skyatnightmagazine.com/space-science/puppis-a-supernova-remnantInset is my FOV and the magenta is the X-ray data of the SNR.

THE SWIRL

This set of concentric rings is what initially drew me to the object.

A recent paper by Parviz Ghavamian et al https://arxiv.org/pdf/2310.00661, studies this structure and concludes this:

“We suggest the possibility that the Swirl marks a ‘funnel’ carved into the supernova ejecta by a close, massive binary companion at the moment of explosion.”

The suggestion is that as the Supernova occurred the companion star got in the way producing a funnel shape of rings made of different material as the layers blew past the star.

Here’s my data arranged strictly as SHO and heavily stretched to see how the rings differ in makeup. Blue is OIII, Green is SII and Red is Ha.

BBC Sky At Night Magazine picked up on the paper with this article: https://www.skyatnightmagazine.com/space-science/puppis-a-supernova-remnant

“Arguments for a hidden star

With data in hand, they consider whether the Swirl could be material spewed into space by a wind from the progenitor before it went supernova.

If this hypothesis is true, we’d expect the Swirl’s rings to be uniform, with no changes in composition from place to place.

Instead, different rings are made of different things: the outermost one is nitrogen-rich, while inner components show oxygen and sulphur too.

As massive stars reach the end of their lives, they end up with an onion-like interior, their ‘burning’ of nuclear fuel producing layers of different heavy elements.

The pattern seen in the Swirl corresponds to being made up of a series of these layers – though the pattern does break down slightly in the innermost components.

But why do we see a series of rings? This is where the presence of a companion comes in.

If such a star exists, it would have got in the way of material flowing outwards during the supernova, producing a funnel shape, which we see as the Swirl.”

DATA CAPTURE

I had not intended to gather 127 hours of data on this. But after over a month of capture I stacked the data only to find my plate solving was off - significantly affecting the framing. I believe the issue was caused by Voyager syncing to PWI4 and adjusting the model. I removed any reference to syncing from my script and rebuilt the model, which solved the issue. But I needed some extra data to fill in and achieve my desired framing. In the end the faintness of the OIII in particular really needed this level of data so “no harm no foul”.

PROCESSING

I tried several approaches to combining the narrowband masters. Even with this much data I was having noise issues in the background. So I decided to add the narrowband to the broadband, primarily to reduce noise in the background. The broadband colors were quite close to what I was after in the narrowband so the blend worked well. This is the combination I used in linear space:

Red: RGB + Ha

Green: RGB + S*.5 + O*.5

Blue: RGB + O

The RGB data was already color calibrated. Adding the narrowband in this way only slightly shifted the background color (I did not remove the NB background but did remove the stars). After adding the narrowband I ran Background Neutralization to clean up the small shift.

The S data was quite different from the H data so that allows us to see the S as orange or yellow in the image.

LAST THOUGHT

What the heck is this? I haven’t been able to find reference to it yet. It sure looks like Wolf-Rayet star is involved and reminds my of the Crescent nebula.