Astronomers have made an exciting discovery about an aging red giant star known as π1 Gruis, or pi-one-Gru. This star is about 530 light-years from Earth and is in a fascinating phase called the asymptotic giant branch (AGB). During this phase, the star has expanded dramatically, becoming 350 to 400 times the size of our sun and shining thousands of times brighter. This expansion presents challenges when trying to identify any nearby stars that may be orbiting it.
To solve this, scientists used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, a powerful tool with 66 radio antennas. “A key part of understanding the orbit of the companion is knowing the mass of the AGB star,” said Yoshiya Mori, the lead researcher from Monash University. Their analysis improved our understanding of the star’s mass and how it might interact with its companion star.
Stars become red giants when they run out of hydrogen for nuclear fusion. As their cores contract, the outer layers expand, sometimes reaching up to 1,000 times their original size. As red giants age, they pulsate and shed material into space. Ultimately, similar stars end as white dwarfs, surrounded by a cloud of gas and dust known as a planetary nebula. This process can be complicated if there are close companion stars, which can exert gravitational influence and even siphon mass from the giant star.
Understanding these processes is essential, not just for studying pi-one-Gru, but for predicting what might happen to our sun when it becomes a red giant in about five billion years. This research was published on November 10 in the journal Nature Astronomy.
Recent studies suggest that close companions to red giants may have less elliptical orbits than previously thought. This finding changes our perception of the evolution of companion stars and their effects on red giants. Team member Mats Esseldeurs from KU Leuven noted, “Understanding how close companions behave helps us predict what will happen to planets around the sun.” Such insights may significantly reshape our understanding of stellar evolution and its effects on planetary systems.
In a world where new discoveries about the universe are emerging daily, the implications of these findings could resonate for years to come. The complexities surrounding red giants and their companions not only teach us about individual stars but also about the fate of our own solar system.
