Variable Star Population in the Open Cluster NGC 6819 Observed by the Kepler Spacecraft

0573380 - ASÚ 2024 RIV PL eng J - Journal Article
Sanjayan, S. - Baran, A.S. - Németh, Péter - Kinemuchi, K.
Variable Star Population in the Open Cluster NGC 6819 Observed by the Kepler Spacecraft.
Acta Astronomica. Roč. 72, č. 4 (2022), s. 267-295. ISSN 0001-5237. E-ISSN 0001-5237
Institutional support: RVO:67985815
Keywords : open clusters * associations * variables stars
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 2.2, year: 2022
Method of publishing: Limited access
https://doi.org/10.32023/0001-5237/72.4.3

We present the list of variable stars we found in the Kepler superstamp data covering approximately nine arcminutes from the central region of NGC 6819. This is a continuation of our earlier work. We classified the variable stars based on the variability type and we established their cluster membership based on the available Gaia Data Release 3 astrometry. Our search revealed 385 variable stars but only 128 were found to be cluster members. In the case of eclipsing and contact binaries we calculated the mid-times of eclipses and derived ephemerides. We searched for eclipse timing variation using the observed minus calculated diagrams. Only five objects show significant orbital period variation. We used isochrones calculated within the MESA Isochrones and Stellar Tracks project and derived the average age (2.54 Gyr), average distance (2.3 kpc) and iron content [Fe/H]=-0.01(2), of NGC 6819. We confirm this distance by the one derived from Gaia astrometry of the cluster members with membership probabilities greater than 0.9.
Permanent Link: https://hdl.handle.net/11104/0343844