Stellar Fireworks: Hubble Revisits a Strange Star’s 40-Year Nova Mystery

Hubble Telescope Revisits a Star System That is Still Extraordinarily Hot
If we could gaze down upon the magnificent spiral structure of our Milky Way galaxy from far above, and compress millions of years into seconds, we would see brief bursts of light, like the flashes from cameras popping off at a stadium event. These are novae, where a burned-out star, a white dwarf, ingests gas from a bloated red giant companion it is orbiting. One of the strangest of these events happened in 1975, when a nova called HM Sagittae grew 250 times brighter. It never really faded away as novae commonly do, but has maintained its brightness for decades. The latest Hubble observations show that the system has gotten hotter, but paradoxically faded a little.