\begin{table}%t3 \caption{\label{sp_par}Physical parameters of spectroscopically analyzed stars in Mercer~23.} %\centerline {\small \begin{tabular}{cccccccc} \hline\hline\noalign{\smallskip} Star & Sp Typ & $\log L$ & $\dot{\cal M}$\tablefootmark{a} & $T_{\rm eff}$ & $\log g$ & $E$($J$$-$$K_{S}$)& ($K_{\rm S}$$-$$M_{K_{\rm S}})_0$\\ & & [$L_\odot$]& [${\cal M_\odot}{\rm yr}^{-1}$] & [K] & & & \\ \hline\noalign{\smallskip} Obj1 & O5.5 I & 6.21 & $1.5\times 10^{-5}$ & 35~000 & 3.25 & 1.30 &14.20\\ Obj2 & WNL7-8 & 6.56 & $2.4\times 10^{-5}$ & 38~000 & 3.00 & & \\ Obj3 & B1/2 & 4.39 & & 32~500 & 4.25 & 1.29 &13.64\\ Obj4 & O9/B0 & 4.65 & & 32~500 & 4.25 & 1.32 &14.55\\ Obj5 & B3/4 & & & & & 1.38 &14.49\\ Obj6 & O6 If & 5.86 & $2.1\times 10^{-5}$ & 34~000 & 3.25 & 1.38 &13.67\\ Obj7 & B3/4 & & & & & 1.35 &13.84\\ Obj9 & B1/2 & 4.33 & & 30~000 & 4.25 & 1.37 &13.59\\ Obj10 & O9/B0 & 4.72 & & 30~000 & 4.25 & 1.39 &14.46\\ Obj11 & O9/B0 & 4.64 & & 30~000 & 4.25 & 1.36 &14.36\\ \hline \end{tabular}} \tablefoot{\tablefoottext{a}{Only objects 1, 2 and 6 had a modeled wind component providing a mass loss rate The value given in the table corresponds to a smooth wind. H/He ratio, $\beta$ parameter, clumping factor ($f$) and $V_{\infty}$, needed for the wind models and errors, are given in Sect.~4.4.}} \end{table}