¹Astronomical Institute, Charles University Prague, V Holesovickach 2, CZ-180 00 Praha, Czech Republic
²Astronomical Institute, Academy of Sciences of the Czech Republic, Fricova 298, 25165 Ondrejov, Czech Republic

Present knowledge of basic physical properties of O and B stars, based on orbital and light-curve solutions for eclipsing binaries, is briefly discussed. It is shown that there is a rather satisfactory agreement between observations and theory for normal, well detached binaries. However, a reliable determination of orbital and light-curve solutions for binaries with emission lines is all but easy. Most spectral lines usable for radial-velocity determination are usually affected by a time variable and often unrecognized contribution from the circumstellar matter in the form of emission and/or additional absorption lines. Also the shape of the light curves is affected by the presence of circumstellar matter and formal solutions which do not take these effects into account lead to unrealistic stellar temperatures and radii. Typical situations and some ways how to get around this problem are discussed and illustrated on several particular cases.

invited talk at the workshop New Directions for Close Binary Studies: The Royal Road to the Stars, to appear in Canakkale Onsekiz Mart University Publications
Preprints from hec@sunstel.asu.cas.cz
or on the web at ftp://astro.troja.mff.cuni.cz/hec/can2002.ps