Using data from NASA’s Kepler space probe and ESA’s Gaia space probe, an international team of astronomers conducted a study of six massive stars in the open star cluster NGC 6866. This study aims to better understand the properties of these massive stars and of the cluster as a whole. NGC 6866, also known as OCL 183, is a relatively young open cluster located in the constellation Swan, approximately 3,900 light-years away. Discovered in 1783, many properties of the cluster, including its age, remain uncertain. Led by Karsten Brogaard of the University of Bologna, the team selected and analyzed six massive stars in the helium core combustion (HeCB) phase. They used data from Gaia’s Data Release 3 (DR3) and photometric light curves from the Kepler spacecraft to identify these stars and study their properties. The study found that the six giant planets have an average radius of about 10.1 times that of the Sun and an average mass of about 2.8 times that of the Sun. These stars are significantly smaller than predicted by current stellar models.

In addition, the ages of the stars are estimated to be between 443 and 580 million years old, and the cluster itself is estimated to be about 430 million years old. This suggests that NGC 6866 is younger than previously thought. The researchers note that future asteroid seismic missions, such as the DeNse High Precision Asteroid Seismic stellar fields (HAYDN) planned by ESA, have the potential to explore further details on the properties of the star NGC 6866 and other young open clusters. Overall, this study contributes to our understanding of open star clusters and their role in the formation and evolution of our galaxy.

Source: K. Brogaard et al., Estimating the asteroid seismic age of the open cluster NGC 6866 using Kepler and Gaia, arXiv (2023). DOI: 10.48550/arxiv.2308.12731