What happens when a pair of stars orbits so close to each other that they share stellar material? According to a study led by José Prieto of Ohio State University and quoted by the New Scientist, they look like not unlike a rotating peanut.
Prieto and his team have already found two such binary star arrangements. One lies in dwarf galaxy Holmberg IX about 12 million light years from Earth, while the other is in the Small Magellanic Cloud next to our Milky Way galaxy. The New Scientist has put up a video on YouTube that simulates what the stars should look like:
The discovery of these star systems might solve a "small astrophysical puzzle," the New Scientist says. Stars that become supernovae tend to age into the iron-heavy, red-giant phase of their life cycles beforehand. However, in 2004 and 2006, two supernovae explosions were detected from much younger, yellow stars. Such young stars aren't supposed to have enough iron to go supernova—"unless, perhaps, these supernovae were produced by close-contact binary stars that share an outer envelope."