This is one of the most difficult images I have tried to capture and interpret. It attempts to capture the remnants of two faint overlapping supernova explosions, Puppis A and Vela, located in the southern constellation of Puppis. The Puppis A SNR is about 7000 light years away and is about one degree is apparent diameter, while the Vela SNR is 4 times closer to us and is about 6 degrees in diameter. This image, one degree across, is centered on the Puppis A SNR and is in the upper right quadrant of the Vela SNR. The Puppis A SNR basically fits within this field of view, just barely, although you would never know it by looking at this image. X-ray images of this region clearly capture the classic spherical shapes of the Vela and Puppis A supernova remnants. However, for the Puppis A SNR in particular, the optical view does not map well to the X-ray shape.

I was challenged to capture this tough object by Lawrence Hazel. Curses to you, Larry, for all of the hours I have spend on this image! Joking aside, I love capturing images of unusual objects, and this is certainly one of the oddest and most difficult I have captured. The signals are faint and the objects are low in my sky at -43 degrees declination. I understand now why there are so few images of Puppis A on Astrobin.

It came as a shock to me that I could find no reference information which distinguishes between the optical contributions of the Vela and Puppis A SNRs to this field of view. I believe that the reddish HII structures in this image correspond mainly to the Puppis A SNR, due to a rough correspondence of the optical shape to the X-ray shape. I also believe that the bluish OIII structures correspond mainly to the Puppis A SNR, because of the scale of their structure. The closer Vela SNR may only be contributing fainter red and cyna hues to the image foreground, but I am not sure.

Although several of the typical arcing OIII gas fronts are visible in the image, there are many other structures here that are not familiar to me. Part of this is likely due to density differences in the interstellar medium, but it seems like other mechanisms must be involved as well. These structures are not typical for a SNR, and in fact if I looked at this image without prior knowledge, I don't think I would have recognized this as a SNR.

A hypervelocity neutron star (RX J0822-4300) within Puppis A known as the Cosmic Cannonball is located within this image field of view at center left. The star is moving away from the center of the Puppis A SNR at over 3 million miles per hour, making it one of the fastest moving stars ever found. Alas, neutron stars are tiny and do not show up in any optical images, including this one.