Astronomers from the European Space Agency have used the Herschel space telescope to take an image of a dying star that they believe will provide insights into what our own Sun will look like billions of years into the future.
Called Kappa Coronae Borealis, the star is 1.5 solar masses, making it larger than our Sun. It is about 2.5 billion years old and situated approximately 100 light years from Earth. The star recently entered its subgiant phase, at which point a star begins to grow and engulf planets and asteroids in close proximity. According to the astronomers, obtaining a picture of a dying star with a debris disk and one or more planets is a rare accomplishment.
"The disc has survived the star's entire lifetime without being destroyed," Amy Bonsor of the Institute de Planétologie et d'Astrophysique de Grenoble said. "That's very different to our own solar system, where most of the debris was cleared away in a phase called the Late Heavy Bombardment era, around 600 million years after the Sun formed."
Stars about the size of our Sun usually meet their demise by turning into a red giant, followed by a supernova explosion or a transformation into a white or brown dwarf. According to the astronomers, Kappa Coronae Borealis will keep burning for hundreds of thousands of years. Interestingly, a third body also appears to be present in the star system. The astronomers theorize that the object is either a gas giant planet or a brown dwarf.
"It is a mysterious and intriguing system: is there a planet or even two planets sculpting one wide disc, or does the star have a brown dwarf companion that has split the disc in two?" Bonsor said.
Kappa Coronae Borealis is the first known finding of a subgiant star to have both a debris disc and planets in its orbit and more examples will be needed before determining how unusual the star is.
"Thanks to Herschel's sensitive far-infrared capabilities and its rich dataset, we already have hints of other subgiant stars that may also have dusty discs," Gӧran Pilbratt, ESA's Herschel project scientist, said. "More work will be needed to see if they also have planets."
