\begin{table}%t1
\caption{\label{targets}Stellar parameters of the selected O stars. Spectral types are from \citet{walborn:1973,walborn:1976}. Hipparcos parallaxes were taken from \citet{perryman:1997}. All other parameters were taken from the "preferred solution'' (some stars have more than one possible set of parameters that fits the observations) of \citet{markova:2004}, except for 10 Lac, for which we used \citet{mokiem:2005}.
We show both the distance from Hipparcos and the distance used for the spectral modeling. As this latter value is used to determine the mass-loss rates, this distance was also used for predicting the thermal radio flux. For the preferred solutions of \citet{markova:2004}, we have scaled the distance from the original solution using the absolute magnitudes, as the reddening is assumed to be the same for both solutions.}
\small%\centerline
{
\begin{tabular}{l|lllll}
\hline\hline
                                             & \object{$\xi$~Per}   & \object{$\alpha$ Cam} & \object{15 Mon}	& \object{$\lambda$ Cep} & \object{10 Lac}	      \\
\hline	     
HD number                            	     & 24912		    & 30614		    & 47839		& 210839		& 214680		       \\
Association/Runaway                          & Runaway              & Runaway               & Mon OB1           & Runaway               & Lac OB1 \\
Spectral type                        	     & O7.5III(n)((f))$^{a}$  & O9.5 Ia	    & O7 V ((f))	& O6 I (n)fp		& O9 V  		       \\	
Parallax  (mas)                      	     & $1.84\pm0.70$	    & $0.47\pm0.60$	    & $3.09\pm0.53$	& $1.98\pm0.46$ 	& $3.08\pm0.62$ 	       \\
Hip. distance  (pc)                  	     & $\rm 540^{+330}_{-150}$  & $>$440		    & $\rm 323^{+67}_{-47}$ & $\rm 510^{+150}_{-100}$	& $\rm 320^{+90}_{-50}$	       \\     
Spectral mod. distance (pc)              	     & 895		    & 765		    & 710		& 1089  		& 320\\
Mass (${M}_\odot$)                    & 52                   & 22		    & 25		& 58			& 27     		       \\  
Radius (${R}_\odot$)           	     & 25.2		    & 19.6		    & 9.9		& 23			& 8.3           	       \\  
$T_{\rm eff}$  ($10^3$ K)           	     & 34.0      	    & 31.0		    & 37.5		& 36.2  		& 36.0	       \\
Luminosity ($10^5~{L}_\odot$)         & 7.6                  & 3.2		    & 1.7		& 8.1			& 1.0	       \\ 
Terminal velocity (km s$^{-1}$)              & 2400       	    & 1550		    & 2200		& 2200  		& 1140		    \\
Mass-loss ($10^{-6}~M_\odot$ y$^{-1}$)      & $4.0 \pm 1.0$        & $2.9\pm0.9$	    & $1.2\pm0.3$	& $7.7\pm2.3$    	& $6.1^{+8.8}_{-5.5} \times 10^{-2}$\\ 
\hline
\end{tabular}}
\smallskip
 $^{a}$ This is the spectral type given by \citet{walborn:1973}, however, a spectral type of O7.5I(n)((f)) was adopted by \citet{markova:2004}.
\end{table}