Astronomers have achieved a significant breakthrough with new high-resolution images of Polaris, also known as the North Star. Using the CHARA Array located on Mount Wilson in California, researchers have captured unprecedented details of the star’s surface. This is the first time scientists have been able to observe features such as large bright and dark spots on Polaris, similar to sunspots on our Sun. The advanced imaging technique employed by CHARA, which combines the light from six telescopes to create a single, highly detailed picture, has revealed these surprising features.

New Insights into Polaris’ Surface

The high-resolution images obtained from the CHARA Array have shown that Polaris, a Cepheid variable star, has noticeable surface spots. These spots, which fluctuate in brightness, were not previously detected. According to Dr Gail Schaefer, Director of the CHARA Array, “The CHARA images revealed large bright and dark spots on the surface of Polaris that changed over time.” This discovery is intriguing as Polaris’ variable brightness occurs in a predictable four-day cycle, making it valuable for cosmic distance measurements.

Polaris: A Star in a Triple System

Polaris, which is part of a triple-star system, has been observed to have a companion star that orbits it every 30 years. The challenge of resolving this faint companion, which was first documented by the Hubble Space Telescope in 2005, has been met with innovative techniques. Dr Nancy Evans from the Center for Astrophysics at Harvard & Smithsonian noted that the team used a speckle interferometer from the Apache Point Observatory to aid their observations. The recent study also confirmed that Polaris may be about five times more massive than the Sun, adding further interest to its detailed study.

Future Research Directions

The findings from the CHARA Array’s high-resolution imaging of Polaris provide a new perspective on Cepheid variable stars. The team, including John Monnier from the University of Michigan, plans to continue their observations to better understand the mechanisms behind the surface spots and their impact on the star’s behaviour. The results open up new questions about the star’s rotation and luminosity, which will be explored in future studies.

These groundbreaking observations mark a significant step forward in our understanding of Polaris and Cepheid variables, offering new insights into stellar dynamics and the nature of our North Star.