(ORDO NEWS) — Using three ground-based telescopes in Chile, astronomers searched for variable stars in the open cluster NGC 6611. As a result, they found 95 variables, most of which are members of the cluster.
The discovery and study of variable stars could provide important clues about aspects of stellar structure and evolution.
The study of variables could also be useful for a better understanding of the scale of distances in the universe.
The estimated age of NGC 6611 is less than 3 million years. This is one of the youngest open clusters. It is located about 5500 light years from us.
A group of astronomers led by Gabriela Michalska from the University of Wroclaw decided to study NGC 6611.
Scientists observed the cluster with two telescopes at the Cerro Tololo Inter-American Observatory and one telescope at the Las Campanas Observatory for 34 nights.
In total, the team initially identified 6,038 stars in the NGC 6611 region, but many of them have poor quality photometry.
Further analysis of data from three telescopes led to the discovery of 95 variable stars, and the probability of belonging to the cluster of 61 of them exceeds 80%.
Hence, they were classified as members of the cluster.
According to the study, 49 stars turned out to be irregular variables.
Among them, astronomers have identified 24 candidates for classical T Tauri stars (CTTS) and 13 candidates for faint-lined T Tauri stars (WTTS).
Moreover, out of 21 periodic variables, they found 17 WTTS candidates. This large ratio of WTTS stars to CTTS stars suggests that the star formation process in NGC 6611 is not very active.
17 eclipsing binary stars (EBS) have also been discovered.
Two of them were previously known, and four were recently identified as variables. The scientists added that eight more variables appear to be Delta Scuti stars.
The authors of the paper hope that more accurate observations of NGC 6611 will lead to the discovery of more periodic variables and allow them to calculate standard values ​​in this cluster.
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