Astronomers have discovered that an aging red giant star has a closely orbiting stellar companion, which could be causing havoc to the star's processes. The discovery could help researchers better understand what will happen to Earth and the other solar system planets when the sun transforms into a red giant about five billion years from now.
The red giant in question is π1 Gruis, which scientists affectionately refer to as pi-one-Gru, which is located around 530 light-years from Earth. This red giant has the same mass as our sun, but the fact that it's in its "puffed out" red giant phase — also referred to as the asymptotic giant branch (AGB), due to its position on the Hertzsprung-Russell diagram of stellar evolution — means that π1 Gruis is now 350 to 400 times the size of our star.
