8 papers
Non-LTE Ionization Modeling for Helium and Strontium in Neutron Star Merger Ejecta
Koya Chiba, Masaomi Tanaka, Shinya Wanajo +3
The material ejected from a binary neutron star merger produces "kilonova," a radioactively powered emission at ultraviolet, optical, and infrared wavelengths. The early-phase spec…
Lanthanide Impact on the Infra-Red Spectra of Nebular Phase Kilonovae
Quentin Pognan, Kyohei Kawaguchi, Shinya Wanajo +3
Nebular phase kilonovae (KNe) have significant infra-red (IR) emission thought to be mostly forbidden emission lines from rapid neutron capture (r-process) species in neutron star…
Potassium abundances in extremely metal poor stars: Implications for nucleosynthesis in the final stages of massive star evolution
M. N. Ishigaki, N. Tominaga, W. Aoki +5
We present a potassium (K) abundance analysis in extremely metal-poor (EMP) stars based on high-resolution () spectra obtained with the High Dispersion Spectrograph on…
The -Process Alliance: Enrichment of -process Elements in a Simulated Milky Way-like Galaxy
Yutaka Hirai, Timothy C. Beers, Young Sun Lee +11
We study the formation of stars with varying amounts of heavy elements synthesized by the rapid neutron-capture process (-process) based on our detailed cosmological zoom-in sim…
Detailed Chemical Abundance Analysis of Metal-Poor Turn-Off Stars: One with [Fe/H] < -4 and Three with [Fe/H] < -3
Takuma Suda, Patrick Francois, Shinya Wanajo +3
We present the analysis of four new extremely metal poor turn-off stars thanks to high-resolution spectra obtained with the Subaru/HDS spectrograph. We determined the abundances an…
Self-consistent scenario for jet and stellar explosion in collapsar: General relativistic magnetohydrodynamics simulation with dynamo
Masaru Shibata, Sho Fujibayashi, Shinya Wanajo +3
A resistive magnetohydrodynamics simulation with a dynamo term is performed for modeling the collapsar in full general relativity. As an initial condition, a spinning black hole an…