Evidence for an interstellar origin of stellar shells

It is shown that the hot inner disks around rapidly rotating BA dwarfs ( stars conventionally called shell stars) are accreted from the interstellar medium because such disks rarely occur around stars within the heart of the local interstellar bubble, which has less than 10% of the density surrounding it. A working model is one in which stars accrete disks in dense interstellar regions, but in regions of low interstellar density, such as the local interstellar bubble, the stellar winds exceeds the accretion rate.