Supernova explosions and star formation in the early universe

We study the formation of low-mass and extremely metal-poor stars in the early universe. We propose a model that early supernova (SN) explosions trigger the formation of low-mass stars via shell fragmentation. We first perform one-dimensional hydrodynamic calculations until an SN shell expanding through the metal-deficient interstellar medium becomes gravitationally unstable and fragments. We then calculate the evolution of the fragment core semi-analytically. The core eventually fragments again by the dust cooling and we show the low-mass protostars form in the extremely metal-poor environment.