The massive eclipsing system ALS 1135 and variable stars in the field of the distant OB association Bochum 7

The masses of both components were derived with an accuracy better than 1 per cent, and their radii, with an accuracy better than 3 per cent. Since the primary's mass is equal to about 25M, its radius was subsequently used to derive the age of the system which is equal to 4.3 ± 0.5Myr.

The result shows that this method represents a viable alternative to isochrone fitting. A photometric search of the field of ALS 1135 resulted in the discovery of 17 variable stars, including 7 pulsating ones. One of them is a slowly-pulsating B (SPB) star belonging to Vel OB1, the other six are δ Scuti stars.