New spectroscopic observations of the B[e]/K binary system MWC 623

The B[e]/K binary system MWC623 was reinvestigated using new spectroscopic observations. The absorption lines of the K and the B star do not exhibit a ny significant radial velocity variations over a time interval of 14 years. The spectral classification using a recent echelle spectrum yielded spectr al types of K2II-Ib and B4III. The luminosity class of the K star gives an estimate of the distance towards MWC623 of 2.4(-0.9)(+1.4) kpc. This is con sistent with the kinematic distance of 2.0(-0.3)(+0.6) kpc. The masses deri ved from the locations of the binary components in the H-R diagram are 7 +/ -1.5 M-circle dot and 7.5 +/-2.5 M-circle dot for the B and K star, respect ively, i.e. the mass ratio is close to 1. Both stars are coeval with an age of 50(-20)(+10) Myr as shown by the comparison with isochrones. The high l uminosity of the K star excludes a pre-main sequence evolutionary phase as explanation for the strong Li I lambda 6708 absorption line observed in the late-type component. Rather, the high lithium abundance is a consequence o f the young age. Likewise, the B[e] star is a slightly evolved object start ing it post-main sequence evolution.