The Gaia-ESO survey: the inner disk intermediate-age open cluster NGC 6802

Milky Way open clusters are very diverse in terms of age, chemicalcomposition, and kinematic properties. Intermediate-age and old openclusters are less common, and it is even harder to find them inside thesolar Galactocentric radius, due to the high mortality rate and strongextinction inside this region. NGC 6802 is one of the inner disk openclusters (IOCs) observed by the Gaia-ESO survey (GES). This cluster isan important target for calibrating the abundances derived in the surveydue to the kinematic and chemical homogeneity of the members in openclusters. Using the measurements from Gaia-ESO internal data release 4(iDR4), we identify 95 main-sequence dwarfs as cluster members from theGIRAFFE target list, and eight giants as cluster members from the UVEStarget list. The dwarf cluster members have a median radial velocity of13.6 +/- 1.9 km s(-1), while the giant cluster members have a medianradial velocity of 12.0 +/- 0.9 km s(-1) and a median [Fe/H] of 0.10+/- 0.02 dex. The color-magnitude diagram of these cluster memberssuggests an age of 0.9 +/- 0.1 Gyr, with (m - M)(0) = 11.4 and E(B - V)= 0.86. We perform the first detailed chemical abundance analysis of NGC6802, including 27 elemental species. To gain a more general pictureabout IOCs, the measurements of NGC 6802 are compared with those ofother IOCs previously studied by GES, that is, NGC 4815, Trumpler 20,NGC 6705, and Berkeley 81. NGC 6802 shows similar C, N, Na, and Alabundances as other IOCs. These elements are compared withnucleosynthetic models as a function of cluster turn-off mass. Thealpha, iron-peak, and neutron-capture elements are also explored in aself-consistent way.