We investigate the formation of extremely metal-poor (EMP) stars that are observed in the Galactic halo and neighboring ultra-faint dwarf galaxies. Their low metal abundances (${\rm [Fe/H]} < -3$) indicate that their parent clouds were enriched by a single or several supernovae (SNe) from the first (Pop III) stars. In this study, we perform numerical simulations of the formation sequence of a...
Dwarf galaxies were the most common type of systems in the Early Universe. The first stars were likely hosted by dwarf galaxies, which might have provided the bulk of ionizing photons driving the early phases of reionization. In the Local Group, metal-poor dwarf galaxies hosting 13 billion years old stars are extremely common. What can we learn from detailed observations of stars in these...
We calculate accretion mass of interstellar objects (ISOs) like Oumuamua onto low-mass population III stars (Pop. III survivors), and estimate surface pollution of Pop. III survivors. An ISO number density estimated from the discovery ofOumuamua is so high ($\sim 0.2$ au$^{-3}$) that Pop.~III survivors have chances at colliding with ISOs about $10^5$ times per $1$~Gyr. `Oumuamua itself...
1D stellar structure and evolution codes (SSECs) are widely used in astrophysics to determine fundamental stellar properties. Since our theoretical knowledge is incomplete, it is necessary to calibrate these codes empirically, especially free parameters such as the convective mixing length, or $\alpha_{\text{MLT}}$. Historically, we have relied on the Sun for this task. This has resulted in...
