Astronomers find star-inside-star 40 years after first theorized

derekmead writes: After 40 years, astronomers have likely found a rather strange celestial body known as a Thorne–ytkow object (TZO), in which a neutron star is absorbed by a red supergiant. Originally predicted in the 1970s, the first non-theoretical TZO was found earlier this year, based on calculations presented in apaper forthcoming in MNRAS .

TZOs were predicted by astronomer Kip Thorne and Anna ytkow, who wasthen postdoctoral fellow at CalTech. The pair imagined what might happen if a neutron star in a binary system merged with its partner red supergiant.

This wouldn’t be like two average stars merging. Neutron stars are the ancient remnants of stars that grew too big and exploded. Their cores remain small—about 12.5 miles—as they shed material out into space. Red supergiants are the largest stars in the galaxy with radii up to 800 times that of our sun, but they aren’t dense.