PF-02-0010

Disk chemical and dynamical evolution at subsolar metallicity

Eduard Vorobyov, Rodrigo Guadarrama, Manuel Guedel, Ryoki Matsukoba, Takashi Hosokawa

Relatively little is known about the formation and evolution of circumstellar disks at metallicities corresponding to the Magellanic Clouds and other moderately metal deficient environments. We present our recent numerical hydrodynamics and thermo-chemical studies of the dynamical and chemical evolution of circumstellar disks around solar mass stars at subsolar metallicities (0.1-0.01 Zsun). Gravitational fragmentation is present in these disks, but the outcome differs from that of the solar metallicity disks as the metallicity drops below 0.1 Zsun. The chemical evolution of subsolar metallicity disks also differs from that of the solar metallicity counterparts. We find that the abundances of basic molecules in lower metallicity disks cannot be understood or reproduced by scaling down the respective species abundances of the reference solar metallicity model. This is because the chemical reactions responsible for the destruction and formation of the studied molecules change as the metallicity of the disk is reduced. We found a strong overabundance (relative to scaled down values) in the models with lower metallicity for gaseous species CN, CO, HCO+, and N2H+, which are particularly useful in observations.

[Poster PDF File]