The North Star, Polaris, has been found to have a spotted surface in the first close-up image captured by astronomers. The image by the Center for High Angular Resolution Astronomy (CHARA) Array reveals large bright and dark spots on the star’s surface. “The CHARA images revealed large bright and dark spots on the surface of Polaris that changed over time,” said Gail Schaefer, director of the CHARA Array.
This marks the first time a Cepheid variable, a class of pulsating stars that includes Polaris, has been observed up close. Polaris is part of a triple star system and is located almost directly above Earth’s North Pole, making it a steadfast point of reference in the nighttime sky. As a Cepheid variable, Polaris pulsates radially, varying in diameter and temperature, which causes regular changes in its brightness.
Polaris’ spotted surface revealed
The researchers, led by Nancy Evans from the Harvard & Smithsonian’s Center for Astrophysics, aimed to use CHARA to measure the 30-year-long orbit of Polaris’ fainter companion star. The slight separation and large contrast in brightness between the two stars makes it extremely challenging to resolve the binary system during their closest approach,” said Evans.
The study also found that Polaris has a mass five times that of the Sun and a diameter 46 times larger. Cepheid variables like Polaris are crucial for astronomers because their true brightness depends on their pulsation period, making them essential tools for determining cosmic distances and measuring the universe’s expansion rate. We plan to continue imaging Polaris in the future,” said John Monnier, an astronomy professor at the University of Michigan.
“We hope to better understand the mechanism that generates the spots on the surface of Polaris.”
The findings were published in The Astrophysical Journal and provide new insights into the behavior and characteristics of Cepheid variables, which are vital cosmic markers for astronomers.
