Dozens of Variable Stars Were Spotted in the Open Cluster NGC 6611

Astronomers have used three ground-based telescopes in Chile to search for variable stars in the open cluster NGC 6611. They identified 95 variable stars, most of which are likely cluster members. This discovery was published in the Monthly Notices of the Royal Astronomical Society on February 1st.

Studying variable stars can provide essential insights into stellar structure and evolution, and may aid in better understanding the distance scale of the universe.

NGC 6611

NGC 6611 is a young open cluster estimated to be less than three million years old, located approximately 5,500 light years away. It hosts at least two stellar populations and contains an abundant population of O and B-type stars, making it a promising target for variability searches among young and massive stars.

The astronomers, led by Gabriela Michalska of the University of Wrocław, Poland, conducted a variability study of NGC 6611 using two telescopes at the Cerro Tololo Inter-American Observatory and one telescope at Las Campanas Observatory over 34 nights spanning one year.

The team initially identified 6,038 stars in the field of NGC 6611, but most of them had poor-quality photometry. Further analysis resulted in the detection of 95 variable stars, with 61 classified as cluster members based on membership probability calculations. The study found that many of the variable stars were irregular variables, including 24 classical T Tauri stars and 13 weak-lined T Tauri stars candidates. Additionally, the study detected 17 eclipsing binaries and eight Delta Scuti pulsating stars.

The authors of the study hope that more precise observations of NGC 6611 will lead to the discovery of more periodic variables, enabling them to determine the standard magnitudes and colors of stars in this cluster. The high ratio of weak-lined T Tauri stars to classical T Tauri stars suggests that the star-forming process may be inactive in NGC 6611.

Read the original article on PHYS.

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