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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: