  The effects of an accretion disk are crucial to understanding the evolution
of young stars. During the combined evolution, stellar and disk parameters
influence each other, motivating a combined stellar and disk model. This makes
a combined numerical model, evolving the disk alongside the star, the next
logical step in the progress of studying early stellar evolution. We aim to
understand the effects of metallicity on the accretion disk and the stellar
spin evolution during the T~Tauri phase. We combine the numerical treatment of
a hydrodynamic disk with stellar evolution, including a stellar spin model,
allowing a self-consistent calculation of the back-reactions between the
individual components. We present the self-consistent theoretical evolution of
T-Tauri stars coupled to a stellar disk. We find that disks in low metallicity
environments are heated differently and have shorter lifetimes, compared to
their solar metallicity counterparts. Differences in stellar radii, the
contraction rate of the stellar radius, and the shorter disk lifetimes result
in faster rotation of low metallicity stars. We present an additional
explanation for the observed short disk lifetimes in low metallicity clusters.
A combination of our model with previous studies (e.g., a metallicity-based
photo-evaporation) could help to understand disk evolution and dispersal at
different metallicities. Furthermore, the stellar spin evolution model includes
several important effects, previously ignored (e.g., the stellar magnetic field
strength and a realistic calculation of the disk lifetime) and we motivate to
include our results as initial or input parameters for further spin evolution
models, covering the stellar evolution towards and during the main sequence.
