Dozens of variable stars detected in the open cluster NGC 6611

Utilizing three ground-based telescopes in Chile, astronomers have carried out a seek for variable stars within the open cluster NGC 6611. In consequence, they detected 95 variables and the vast majority of them are most definitely cluster members. The invention was printed February 1 within the Month-to-month Notices of the Royal Astronomical Society.

Detecting and learning variable stars may provide vital hints into facets of stellar construction and evolution. Investigation of variables might be additionally useful for a greater understanding of the gap scale of the universe.

With an estimated age of lower than 3 million years, NGC 6611 is likely one of the youngest Galactic open clusters. It’s positioned some 5,500 light years away and hosts a minimum of two stellar populations. Earlier observations of NGC 6611 have discovered that it incorporates a wealthy inhabitants of the O and B-type stars, which makes it a promising goal for variability searches amongst younger and massive stars.

That’s the reason a group of astronomers led by Gabriela Michalska of the College of Wrocław, Poland, determined to carry out a variability research of NGC 6611. They noticed the cluster with two telescopes at Cerro Tololo Inter-American Observatory (CTIO) and one telescope at Las Campanas Observatory, throughout 34 nights spanning one yr.

“The observations of NGC 6611 had been carried out with three telescopes positioned in Chile. Many of the observations had been taken in no various hours per night time attributable to unhealthy climate or as a background venture,” the researchers wrote within the paper.

In total, the group initially recognized 6,038 stars within the area of NGC 6611, however a lot of them have photometry of poor high quality. Additional inspection of the blended information from the three telescopes led to the detection of 95 variable stars and 61 of them have membership likelihood calculated from correct motions, supplied by ESA’s Gaia satellite, higher than 80%. Subsequently, they had been categorized as cluster members.

In response to the research, 49 stars turned out to be irregular variables. Amongst them, the astronomers recognized 24 classical T Tauri star (CTTS) and 13 weak-lined T Tauri star (WTTS) candidates. Furthermore, out of the 21 periodic variables, they discovered 17 different WTTS candidates. Such a big ratio of WTTS to CTTS stars means that the star-forming course of is just not very energetic in NGC 6611.

The observations additionally detected 17 eclipsing binaries (EBs) within the investigated area of view. Two of them turned out to be beforehand identified EBs, and 4 different binary stars had been newly recognized as variables. The scientists added that eight different variables seem like Delta Scuti pulsating stars.

The authors of the paper hope that extra exact observations of NGC 6611 will end in discovering extra periodic variables and can enable them to calculate the usual magnitudes and colours of the celebrities on this cluster.

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