When supernova explode, they fling gas out into space, creating beautiful, gauzy remnant for us to drool over. Supernova remnant G352 is pretty, but weird. It's collecting extra material, misplaced its neutron star, and looks dramatically different depending on the wavelength.
The strange remnant is located about 24,000 light years from Earth, in the direction of Scorpius. The field of view in this composite is 14.5 arcminutes across, or about 1,000 light-years wide. It's a multi-spectral composite with each colour contribution coming from a different wavelength recorded by a different telescope.
Blue is x-rays, white is visible light, orange is infrared light, and pink is radio waves. X-rays are captured by NASA's Chandra X-ray Observatory. Optical data are from the Digitized Sky Survey. Infrared wavelengths are from the Spitzer Space Telescope, and finally, radio waves are photographed by the National Science Foundation's Karl G. Jansky Very Large Array.
So, how is this not-so-little pretty remnant so strange?
To start with, it appears that G352 is extremely greedy. The remnant has collected nearly 1032 kilograms of material — 45 times the mass of our sun. While all supernova remnants sweep up some additional material as they expand, that's a whole lot more than normal.
Not only that, but those cooler remnants aren't producing nearly as many X-rays as the hotter explosion debris. Most of the emitted X-rays are hotter (30 million degrees Celsius), not cooler (2 million degrees Celsius), suggesting that most of the X-rays are being produced by the explosion debris, and not the material swept up in the intervening time. This would make sense for a baby supernova, but G352 is 2,200 years old, and should have transitioned by now.
Next, check out G352 in different wavelengths. Breaking the composite apart, that's X-rays (blue) in the top left, with visible light (white) in the top right. Moving to the bottom row, the bottom left is infrared (orange), and bottom right is radio waves (pink).
The remnant is nice and bright in X-rays — that's normal. It's almost non-existent in visible light; again, awesome. The globs of infrared off to the sides are not directly related to the supernova, so we can ignore them. The radio waves is where things get unusual: why is the remnant an infilled ellipse in X-ray, but only the outer rings glowing in radio? Just what sort of evolutionary path is this remnant headed down, and what will it look like in the future?
Finally, a supernova this big should have left behind a neutron star, but we aren't finding it. Maybe it produced a faint neutron star, so faint we haven't detected it yet. Or, more exotically, maybe the supernova produced a black hole instead.
Overall, this is a whole lot of weird going on for one explosion. You can read more about how this system is shaping up to be downright strange, and some hypothesis for what's going on, in XMM-Newton and Chandra Observations of the Ejecta-Dominated Mixed-Morphology Galactic Supernova Remnant G352.7-0.1
Image credit: Credit: X-ray: NASA/CXC/Morehead State Univ/T.Pannuti et al.; Optical: DSS; Infrared: NASA/JPL-Caltech; Radio: NRAO/VLA/Argentinian Institute of Radioastronomy/G.Dubner. What more multi-spectral astrophotography? Check out Chandra's observations of a supernova in a binary system, or explore the Milky Way in infrared with Spitzer.