A team of astronomers using the Hubble Space Telescope has found a star system that may have left behind a “zombie star” after an unusually weak supernova explosion. A supernova normally obliterates the exploding white dwarf, and the star effectively dies. Scientists believe this faint supernova may have left behind a surviving portion of the dwarf star—a sort of zombie star. The two inset images show before-and-after images captured by Hubble of Supernova 2012Z in the spiral galaxy NGC 1309. The white X at the top of the main image marks the location of the supernova in the galaxy.
Image Credit: NASA
Pay no attention to the bright star in the center of the picture. The really interesting stellar object in the frame is that blob of red near the bottom. It’s a small white dwarf undergoing a helium flash.
Normally, the white dwarf stage is the end of the life cycle of a low-mass star, but in some rare cases, a star reignites in a helium flash and expands to its previous red giant state. When this happens, huge amounts of gas and dust are ejected before the star shrinks to become a white dwarf again.
A helium flash is a dramatic and short-lived series of events, and this star—Sakurai’s Object, named for the Japanese amateur astronomer who discovered it in 1996—has allowed astronomers a rare opportunity to study a helium flash as it occurred.
Image Credit: ESO
The glowing green planetary nebula IC 1295 surrounds a dim and dying star. It is located about 3300 light-years away in the constellation of Scutum (The Shield). The white dwarf star is softly shedding its outer layers, like an unfolding flower in space. It will continue this process for a few tens of thousands of years.
Image Credit: ESO