Distance moduli of open cluster NGC 6819 from Red Giant Clump stars

• We study open cluster NGC 6819 using data from Kepler space mission.
• Data of Red Giant Clump stars are used to derive distance moduli of NGC 6819.
• Reddening adopted for the whole cluster and individual Red Giant Clump stars.
• Distance moduli obtained with Red Giant Clump stars are in agreement with other methods.
• Red Giant Clump stars can be used as ‘distance candles’ for open cluster NGC 6819.

In this paper we study Kepler open cluster NGC 6819 using Kepler data of Red Giant Clump (RGC) single member (SM) stars. The Kepler data spans a period of 4 years starting in 2009. In particular, we derive distance moduli for each individual RGC star, from which we get the mean distance modulus of μ0 = 11.520 ± 0.105 mag for the cluster when we use reddening from the Kepler Input Catalogue (KIC) for each RGC star. A value of μ0 = 11.747 ± 0.086 mag is obtained when uniform reddening value E(B−V)=0.15E(B−V)=0.15 is used for the cluster. The values of μ0 obtained with RGC stars are in agreement with the values in the literature with other methods. We report for the case of Kepler open cluster NGC 6819 that RGC stars can be used as ‘distance candles’ as has been done in the literature with other open clusters.