AAS 204th Meeting, June 2004
Session 24 Protoplanetary Disks and the Brown Dwarf Desert
Oral, Monday, May 31, 2004, 2:00-3:30pm, 601

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[24.01] Evidence for an Interstellar Origin for Hot Inner Disks around Rapidly Rotating Early-type Stars

H. A. Abt (KPNO)

At any one time, about one quarter of the rapidly rotating early-type stars show sharp absorption lines due to hot inner disks (temperatures ~ 10,000 K). The lines appear and disappear on time scales of decades, indicating that they are ephemeral, not primordial. Because no such lines occur around stars with projected rotational velocities less than about 200 km/s, the lines are formed in disks, not spherical shells. We looked in the cores of H alpha for disk lines in 181 rapidly rotating B9-A5 V or IV stars and all 97 northern shell stars listed in the Bright Star Catalogue. It was found that the 145 stars without disk lines are well distributed in galactic coordinates, but the 87 stars with disk lines avoid the core of the local interstellar bubble. A working model is that in dense regions these stars may accrete disks, but where the interstellar density is less than 10% than that outside the bubble, the stars loose them due to strong winds.

The author(s) of this abstract have provided an email address for comments about the abstract: abt@noao.edu

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