Stellar companions and the age of HD 141569 and its circumstellar disk

We investigate the stellar environment of the beta Pictoris-like star HD 14 1569 with optical spectroscopy and near-infrared imaging. The B9.5 Ve prima ry and two other stars (types M2 and M4) both located in projection less th an 9 " away have the same radial velocity and proper motion and therefore a lmost certainly form a triple star system. From their X-ray flux, lithium a bsorption, and location on pre-main-sequence evolutionary tracks, the compa nions appear to be 5 Myr old. HD 141569A is now one of the few main-sequenc e stars with a circumstellar disk that has a well-determined age. The circu mstellar disk is composed of secondary debris material, thus placing an upp er limit on the time needed for disk processing. These three stars may be p art of an association of young stars.