Analyses of multi-epoch , high-resolution ( R \sim 50000 ) optical spectra of seven early-type systems provided various important new insights with respect to their multiplicity .
First determinations of orbital periods were made for HD 92206 C ( 2 \aas@@fstack { d } 022 ) , HD 112244 ( 27 \aas@@fstack { d } 665 ) , HD 164438 ( 10 \aas@@fstack { d } 25 ) , HD 123056 A ( \sim 1314 d ) and HD 123056 B ( < 2 d ) ; the orbital period of HD 318015 could be improved ( 23 \aas@@fstack { d } 445975 ) .
Concerning multiplicity , a third component was discovered for HD 92206 C by means of He i line profiles .
For HD 93146 A , which was hitherto assumed to be SB1 , lines of a secondary component could be discerned .
HD 123056 turns out to be a multiple system consisting of a high-mass component A ( \approx O8.5 ) displaying a broad He ii 5411 Å feature with variable radial velocity , and of an inner pair B ( \approx B0 ) with double He i lines .
The binary HD 164816 was revisited and some of its system parameters were improved .
In particular , we determined its systemic velocity to be -7 km s ^ { -1 } , which coincides with the radial velocity of the cluster NGC 6530 .
This fact , together with its distance , suggests the cluster membership of HD 164816 .
The OB system HD 318015 ( V1082 Sco ) belongs to the rare class of eclipsing binaries with a supergiant primary ( B0.5/0.7 ) .
Our combined orbital and light-curve analysis suggests that the secondary resembles an O9.5 III star .
Our results for a limited sample corroborate the findings that many O stars are actually massive multiple systems .