All Tables

Table 1: Stellar parameters of the selected O stars. Spectral types are from Walborn (1973,1976). Hipparcos parallaxes were taken from Perryman et al. (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 Markova et al. (2004), except for 10 Lac, for which we used Mokiem et al. (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 Markova et al. (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.
Table 2: Radio detections as a function of wavelength of our targets reported in the literature. When several measurements are available a weighted average is shown; upper limits are 3 $\sigma$ . Fluxes are from [1] Abbott et al. (1980), [2] Bieging et al. (1989), [3] Drake (1990), [4] Lamers & Leitherer (1993) and [5] Scuderi et al. (1998).
Table 3: Results of our new WSRT and archival VLA observations. The upper limits shown are 5 $\sigma$ upper limits.