@cosmic__explorer: 17,000 light-years | Blast wave velocity up to 13.8 million mph (2% c) X-ray observations spanning 2000 to 2025 reveal structural asymmetry in the shockwave propagation of Kepler’s Supernova Remnant. The southern margin expands at ~13.8M mph into low-density ambient gas, while the northern margin decelerates to ~4M mph due to collision with a denser circumstellar medium. Tracking these multi-decadal velocity vectors allows astrophysicists to reconstruct the progenitor system's mass-loss history prior to the Type Ia thermonuclear detonation. If the blast wave's deceleration directly measures interstellar gas density, how accurately can we model the original mass of the companion star before the explosion? #astrophysics #Astronomy #supernova #chandraxray #stellarphysics