06Nov2006Ge/Ay133

How are disks dissipated?

Hollenbach 2006, Cambridge Disks Meeting

Early disk evolution (infall from envelope):

Intermediate disk evolution (pre-main sequence):

The Radial & Vertical Chemical Structure of Disks

X-rays

R=300 AU

To clear the inner disk,

Chemistry can have a large influence on the thermal structure:

Jonkheid et al. (2004) UV field critical…

Dominated by Ly α and other lines! This has a large impact on the chemistry (CO, OH, CN, etc. do not photolyze at Ly α).

What does the VUV spectrum of a T Tauri star look like?

Heavy/Light lines = BP Tau/TW Hya

Bergin et al. (2003)

External Photoevaporation scenario:

Orion Proplyd

Local resonances canpropagate globally!

External Photoevaporation – Now SURFACE AREA Driven (Rapidly Shrinks)

Hollenbach et al. (2000, PP IV)

Putting it all together:A comparison of various disk dispersal mechanisms

The stellar encounter (SE) and external photo-evaporation time scales are calculated for the core of the Orion proto-stellar cluster.

What are the dominant processes at various disk radii?

VI. What are some of the implications?

Local resonances canpropagate globally!

Linbladresonanceequations: