An X-Ray Proper-motion Study of the Large Magellanic Cloud Supernova Remnant 0509-67.5
Benson T. Guest et al 2022 AJ 164 231
X-ray observations of an extragalactic supernova remnant show that the remnant is expanding at a blistering 6,120 kilometers per second, which suggests that the surrounding interstellar medium is low density.