When the researchers examined the entire system, they discovered that it is unique, offering astronomers a phenomenon not seen before among systems with massive stars. “It’s a missing link in binary star evolution,” says astrophysicist Maxwell Moe of the University of Arizona in Tucson, who was not involved in the new research.
For years, astronomers have noticed binary systems in which one star is actively tugging gas away from the other, and they’ve seen systems with a donor star that’s merely a naked stellar core. But HR 6819’s donor star has stopped providing mass to the recipient. “It still has a little bit of envelope left, but it’s rapidly contracting, evolving into a remnant core,” Moe adds.
The researchers are using the Very Large Telescope Array to track HR 6819 for a year in order to measure exactly how the stars are moving. “We want to really understand how the individual stars in the system tick,” she adds. The team will then utilize that data in computer calculations of binary star evolution simulations. It’s exciting to have a system at hand now that we can use as a foundation for further study.