Pismis 18 photometry and radial velocities

Cluster abundance measurements of six radial-velocity member stars with UVES high-resolution spectroscopy are presented for 23 elements. The average radial velocity of 26 high confidence members is -27.5+/-2.5(std)km/s with an average proper motion of pmra=-5.65+/-0.08(std)mas/yr and pmdec=-2.29+/-0.11(std)mas/yr. According to the new estimates, based on high confidence members, Pismis 18 has an age of {tau}=700^+40^_-50_Myr, interstellar reddening of E(B-V)=0.562^+0.012^_-0.026_mag and a de-reddened distance modulus of DM_0_=11.96^+0.10^_-0.24_mag.

The median metallicity of the cluster (using the six UVES stars) is [Fe/H]=+0.23+/-0.05dex, with [{alpha}/Fe]=0.07+/-0.13 and a slight enhancement of s- and r- neutron-capture elements. With the present work, we fully characterized the open cluster Pismis 18.We confirmed its present location in the inner disc. We estimated a younger age than the previous literature values and we gave, for the first time, its metallicity and its detailed abundances.

Its [{alpha}/Fe] and [s-process/Fe], both slightly super-solar, are in agreement with other inner-disc open clusters observed by the Gaia-ESO survey.