Red Giant Star’s companion Reveals Future of Our Sun

Astronomers have discovered a closely orbiting stellar companion around an aging red giant star, potentially disrupting its normal processes. This discovery offers valuable insights into what will happen to Earth and the other planets in our solar system when the sun transforms into a red giant in approximately five billion years.

The red giant, π1 Gruis (pi-one-Gru), resides about 530 light-years from Earth. While it has the same mass as our sun, its evolved state – the “puffed out” red giant phase, also known as the asymptotic giant branch (AGB) – means π1 Gruis is now 350 to 400 times larger than our star.

π1 Gruis also shines thousands of times brighter than the sun, making it incredibly difficult to detect orbiting companions, even if those companions are stars themselves.Finding companions to AGB stars has historically been a challenge. This team overcame this obstacle by utilizing the Atacama Large Millimeter/submillimeter Array (ALMA), a powerful array of 66 radio antennas in northern Chile.

ALMA excels at detecting the cool carbon monoxide gas surrounding aging stars. This gas reveals the presence of a companion star through subtle distortions in the gas’s movement.The team found a companion roughly 60% of the sun’s mass, orbiting π1 Gruis at a distance similar to that between Earth and Mars.

“This companion star is highly likely responsible for the unusual shape of the gas around π1 Gruis,” explains study lead author Dr. Maarten van den Besselaar, a PhD student at Radboud University in the Netherlands. “It’s disrupting the flow of gas and dust as the red giant expands, creating a complex and asymmetrical structure.”

Understanding these interactions is crucial.As our sun enters its red giant phase, it will expand and engulf Mercury and Venus, and potentially Earth. The presence of a companion star could substantially alter this process, potentially pushing planets into different orbits or even ejecting them from the solar system.

This research isn’t just about π1 Gruis. It provides a template for studying other red giants and their companions,helping astronomers refine their models of stellar evolution and predict the ultimate fate of planetary systems like our own. The team plans to continue observing π1 Gruis with ALMA to further unravel the dynamics between the red giant and its companion.