Shp. Alencar et al., ABSOLUTE DIMENSIONS OF ECLIPSING BINARIES .21. V906 SCORPII - A TRIPLE SYSTEM MEMBER OF M7, Astronomy and astrophysics, 326(2), 1997, pp. 709-721
We present an analysis based on new uvby light curves and spectroscopi
c data of the detached triple-lined B-type type eclipsing binary V906
Sco. The uvby light curves are analysed with an extended version of th
e Wilson-Devinney program. The spectroscopic CCD observations are anal
ysed with both the Sterne and the Lehmann-Filhes methods. We conclude
from the combined analysis that the triple system V906 Sco is a member
of the open cluster M 7 and that its B-type eclipsing components are
still on the main sequence, at an age of (2.4 +/- 0.3) x 10(8) yrs, al
ready close to the TAMS (especially the more massive one). The system
is older than the time for circularization of the orbit, and the small
eccentricity is probably caused by the third component, which, howeve
r, is unlikely to be the main responsible for the apsidal motion, prob
ably more influenced by tidal and rotational deformation. We determine
absolute dimensions of high precision (errors < 2%): M-A = 3.25 +/- 0
.07, R-A = 3.52 +/- 0.04, M-B = 3.38 +/- 0.07 and R-B = 4.52 +/- 0.04,
in solar units. The system is detached, with both components in synch
ronous rotation, and therefore representative for normal stars.