Asteroseismic and Astrometric Characterization of Members in the NGC 6866 Open Cluster

Abstract

Kepler, a NASA space telescope, has revolutionized our understanding of star clusters. Among the four open star clusters (OSCs) in its field of view (FOV), New General Catalogue (NGC) 6866 is the youngest and least studied. Young open clusters like NGC 6866 are expected to harbor a rich population of δ Scuti and binary stars, primarily main-sequence stars. However, studying OSCs poses a challenge in identifying true cluster members. How can asteroseismic and astrometric characterization of member stars in the NGC 6866 OSC, particularly focusing on binary systems, be used to estimate the age and distance of the cluster? In this work, we aimed to address this challenge by distinguishing between members and nonmembers of NGC 6866. Identifying member stars is crucial for searching for binary stars, which can then be used to determine the age and distance of the cluster. Gaia, the European Space Agency's (ESA) flagship astrometric mission, has enabled unprecedented insights into the Milky Way galaxy, including its structure, dynamics, and evolution. Data from the Gaia and Kepler satellites were employed to distinguish between stars that belong to the NGC 6866 open cluster and those that do not. We obtained the Gaia satellite data from the VizieR database for stars located within a 10 arcmin radius from the cluster's center. Additionally, we analyzed Kepler photometric data extracted by Balona et al. (2013a). To identify potential members, we calculated the distance moduli (using parallax) for the selected stars and plotted them on a HertzsprungRussell (H-R) diagram, which helped us determine their positions within the cluster. We also used proper motion as an additional criterion for discriminating between cluster members and non-members. Our analysis revealed 14 newly categorized δ Scuti stars situated along the main sequence of the NGC 6866 OSC. Furthermore, we identified a single binary star system, Kepler Input Catalogue (KIC) 8196903, among the δ Scuti stars using the binarogram technique. Ultimately, our estimation placed the age of the NGC 6866 OSC at approximately 0.86 Gyrs and determined its distance to be roughly 1497.90 parsecs (pc). This study highlights the need for larger datasets, longer observation periods, novel techniques, and utilizing the latest data releases to achieve a more comprehensive understanding of Open Star Clusters