There’s plenty to learn from the skeletons left behind after supernova explosions tear through their surroundings. An X-ray view from space has revealed new details about a particularly extreme supernova remnant.
NuSTAR observations showing the spatial distribution of flux that indicates where overionized plasma resides in supernova remnant W49B. The overionized plasma is more highly concentrated on the western side of the remnant. [Yamaguchi et al. 2018]When some stars explode as powerful supernovae at the end of their lifetimes, they expel material into their surroundings, enriching the galaxy with heavy elements. As this matter is flung outwards at high speeds, it slams into the interstellar medium, generating shocks that heat the gas and ionize it.
We can study the young remnants of supernovae — the structures of gas and dust left behind shortly after these explosions — to learn more about how supernovae interact with the interstellar medium. One type of source is particularly intriguing: very young, hot supernova remnants that are “overionized”.
Overionized plasmas send us mixed signals: their level of ionization is higher than what we expect from the temperature we measure from their electrons. This is most likely an indication that the plasma has recently ...