Researchers at Georgia State University's Center for High Angular Resolution Astronomy (CHARA) Array have made groundbreaking discoveries about the North Star, also known as Polaris. Their findings, published in The Astrophysical Journal, provide unprecedented insights into the size, appearance, and behavior of this iconic celestial object.

Polaris, located at the North Pole of Earth, serves as a significant navigational aid and holds its own astronomical significance. It is part of a triple-star system and is classified as a pulsating variable star. The star undergoes regular fluctuations in brightness as its diameter expands and contracts over a four-day cycle.

Cepheid variables, the classification to which Polaris belongs, play a crucial role in astronomy. These stars, known as "standard candles," emit varying levels of brightness based on their pulsation period. By gauging a Cepheid's true luminosity, astronomers can accurately measure distances to galaxies and even determine the rate of the universe's expansion.

Led by Nancy Evans from the Center for Astrophysics at Harvard & Smithsonian, a team of astronomers embarked on a mission to observe Polaris using the advanced CHARA optical interferometric array of six telescopes at Mount Wilson, California. Their primary objective was to map the orbit of Polaris' close companion, which completes its orbit every 30 years.

However, capturing clear images of the binary system's close approach proved challenging due to the significant brightness difference and small separation between the two stars. Nevertheless, utilizing the collective power of the CHARA Array's telescopes, the researchers successfully detected the faint companion as it passed near Polaris.

The observations of Polaris were aided by the cutting-edge MIRC-X camera, developed jointly by astronomers at the University of Michigan and Exeter University in the United Kingdom. Equipped with the extraordinary capability to uncover intricate details of stellar surfaces, the camera played a pivotal role in this study.

The team's breakthrough came with astonishing revelations about Polaris' size and appearance. Tracking the orbital motion of the companion star helped researchers determine that Polaris possesses a mass five times greater than that of the sun. Additionally, detailed images unveiled a diameter 46 times larger than our sun's. Most intriguingly, the images revealed larger bright and dark spots on the surface of Polaris, which evolved over time.

Gail Schaefer, director of the CHARA Array, explained, "The CHARA images provided us with the first-ever glimpse of the surface of a Cepheid variable. We observed notable bright and dark spots that demonstrated variability."

Further investigations indicated that the presence of these spots and the star's rotation might be linked to a 120-day variation in measured velocity. This finding has sparked a desire within the scientific community to continue studying Polaris to uncover the mechanisms behind these intriguing surface features.

John Monnier, an astronomy professor at the University of Michigan, expressed their intentions to delve deeper into Polaris, stating, "We plan to continue imaging Polaris in the future. Our aim is to gain a better understanding of the mechanisms responsible for the formation of spots on its surface."

Remarkably, the observations of Polaris were made possible through the open access program at the CHARA Array, allowing astronomers worldwide to apply for research time through the National Optical-Infrared Astronomy Research Laboratory (NOIRLab).

The newfound understanding of Polaris, the North Star, not only deepens our comprehension of this prominent celestial object but also contributes to the wider field of astronomy. With ongoing research, scientists hope to unravel the secrets of Polaris, shedding light on the complex dynamics of Cepheid variables and uncovering further mysteries hidden within our infinite universe.