講演者: Ingrid Mann (神戸大学 大学院自然科学研究科 教授)   
  題名: Dust Destruction in Planetary Systems: Refuting the P-R Paradigm
  日時: 2006年05月12日（金）12:20-13:10
  場所: 自然科学3号館6階セミナー室 609号室






The Poynting-Robertson (P-R) effect gradually reduces orbital energy
and angular momentum of dust particles in bound orbit about a star.
The time span for particles to fall into the star as a result of the
P-R effect is much shorter than the age of main-sequence stars and
also shorter than the age of many pre-main sequence stars observed to
have dust shells. This comparison of the time scales is often given
as a proof that the dust clouds are not remnants of the star and/or
planetary system formation but rather are replenished by planetary
objects orbiting the stars. Though the P-R lifetime is short compared
to the age of the central star, in many cases the PR effect it not
the main process to limit the lifetime of dust, not even in the solar
system. In this presentation I will discuss processes of dust
formation and dust destruction by collisions and by stellar wind
interactions. I will then present examples how these processes
determine the dust distributions and are therefore important for
studying planetary debris disks including our own solar system dust
cloud.