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

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