EVIDENCE OF AN ACCRETION DISK AROUND THE HERBIG AE/BE STAR MWC 297

Absract The article discusses most young, low-mass stars are surrounded by circumstellar disks. The same is also true for intermediate-mass stars up to a spectral type of ∼B8. Direct detections of disks around early B or O stars are rare. This does not mean that high-mass stars do not have accretion disks; rather, it indicates that disks are much more short-lived around high-mass stars, so that by the time these stars become optically visible they have already dispersed their accretion disks. Furthermore, high-mass stars are generally more distant than low-mass stars, making it harder to spatially resolve their accretion disks. Even O stars with stellar masses of 20–30 Me appear to have disks in their heavy accretion phase. However, such stars are difficult to study.