The brightest star (lucida) of NGC 6940 is the red giant FG Vulpeculae, a semiregular variable star whose magnitude ranges from 9.0 to 9.5 every 80 days approximately.

[3] NGC 6940 is rich in red giants, more than 20 according to WEBDA database.

Based on the spectroscopic analysis of twelve of them, the cluster age was estimated to be 1.1 billion years, with a turn-off mass of 2 M⊙.

[7] Three of these sources were identified as binary stars, from a total of six known to exist in the cluster.

The luminosity of the sources was typical of RS Canum Venaticorum variables, close binaries that could retain very active coronal sources despite the age of the cluster.