2,000-year-old ‘guest star’ mystery from 185 AD solved by NASA X-ray study

Ancient Chinese astronomers saw a bright guest star in 185 AD. This supernova remnant, RCW 86, was unusually large. New research reveals the star exploded in a hidden bubble it created. This allowed debris to expand rapidly. A 'bounce back' effect from denser gas sent shockwaves, reheating gas. Chandra X-rays confirmed this. Synopsis Ancient Chinese astronomers saw a bright guest star in 185 AD. This supernova remnant, RCW 86, was unusually large. New research reveals the star exploded in a hidden bubble it created. This allowed debris to expand rapidly. A 'bounce back' ... [3594 chars]