1 Introduction

In this paper, new spectroscopic results for V337 Aql, V649 Cas, V382 Cyg, and V431 Pup are presented. Though various spectroscopic investigations of these eclipsing binary systems can be found in literature, there were reasons to revisit these objects on the basis of new observations: for V337 Aql and V431 Pup no orbits had been published yet; for V649 Cas the presence of a third body was already suggested by van Hamme (1992) - if confirmed, the strange masses found for this binary would eventually change to acceptable values; in case of V382 Cyg, rather different values of the radial velocity semi-amplitudes appeared in studies published by now.

The composite spectral type of our stars was classified as B 0.5p for V337 Aql (Hiltner 1956), B 0 Vn for V649 Cas (Cowley 1972), O 8 for V382 Cyg (Hiltner 1956), and B 1 III for V431 Pup (Feast et al. 1955). A rather wide range of deviating masses, partly inconsistent with the spectral types, had been given for such stars in previous studies. New investigations appeared necessary to clarify such discrepancies.