436 citations · 1.1k across the 19 of their papers we have counts for
19 papers
A comparative study on three modes of s-process nucleosynthesis in extremely metal-poor AGB stars
S. Yamada, T. Suada, Y. Komiya +2
Carbon-enhanced metal-poor (CEMP) stars in the Galactic halo have a wide range of neutron-capture element abundance patterns. To identify their origin, we investigated three modes…
Are Faint Supernovae Responsible for Carbon-Enhanced Metal-Poor Stars?
Yutaka Komiya, Takuma Suda, Shimako Yamada +1
Mixing and fallback models in faint supernova models are supposed to reproduce the abundance patterns of observed carbon-enhanced metal-poor (CEMP) stars in the Galactic halo. A fi…
R-process Element Cosmic Rays from Neutron Star Mergers
Yutaka Komiya, Toshikazu Shigeyama
Neutron star mergers (NSMs) are one of the most plausible sources of r-process elements in the universe. Therefore NSMs can also be a major source of ultra-heavy elements in cosmic…
Contribution of Neutron Star Mergers to the R-process Chemical Evolution in the Hierarchical Galaxy Formation
Yutaka Komiya, Toshikazu Shigeyama
The main astronomical source of r-process elements has not yet been identified. One plausible site is neutron star mergers (NSMs), but from perspective of the Galactic chemical evo…
Population III stars around the Milky Way
Yutaka Komiya, Takuma Suda, Masayuki Y. Fujimoto
We explore the possibility of observing Population III (Pop~III) stars, born of the primordial gas. Pop~III stars with masses below should survive to date though are…
The most iron-deficient stars as the polluted population III stars
Yutaka Komiya, Takuma Suda, Masayuki Y. Fujimoto
We investigate the origin of the most iron-poor stars including SMSS J031300.36-670839.3 with [Fe/H] < -7.52. We compute the change of surface metallicity of stars with the accreti…
Properties of Galaxies around AGNs with Most Massive Supermassive Black Hole Revealed by the Clustering Analysis
Yuji Shirasaki, Yutaka Komiya, Masatoshi Ohishi +1
We present results of the clustering analysis between active galactic nuclei (AGNs) and galaxies at redshift 0.1-1.0 for investigating properties of galaxies associated with the AG…
The New Model of Chemical Evolution of r-process Elements Based on The Hierarchical Galaxy Formation I: Ba and Eu
Yutaka Komiya, Shimako Yamada, Takuma Suda +1
We investigate the chemical enrichment of r-process elements in the early evolutionary stages of the Milky Way halo within the framework of hierarchical galaxy formation using a se…
Current signatures and search for Pop. III stars in the Local Universe
Yutaka Komiya, Takuma Suda, Masayuki Fujimoto
Recent numerical studies argue that low-mass stars can be formed even at zero-metallicity environment. These low-mass Population III(Pop.~III) stars are thought to be still shining…
The Stellar Abundances for Galactic Archaeology (SAGA) Database III - Analysis of Enrichment Histories for Elements and Two Modes of Star Formation during the Early Evolution of Milky Way
Shimako Yamada, Takuma Suda, Yutaka Komiya +2
We study the enrichment histories for nine elements, C, four alpha-elements of Mg, Si, Ca, and Ti, Sc, and three iron-peak elements of Co, Ni, and Zn, by using a large number of st…
A Cross-correlation Analysis of AGN and Galaxies using Virtual Observatory: Dependence on Virial Mass of Super-Massive Black Hole
Yutaka Komiya, Yuji Shirasaki, Masatoshi Ohishi +1
We present results of the cross-correlation analysis between active galactic nuclei (AGNs) and galaxies at redshift 0.1-1. We obtain data of ~10,000 SDSS AGNs in which their virial…
Transition of the Stellar Initial Mass Function Explored with Binary Population Synthesis
Takuma Suda, Yutaka Komiya, Shimako Yamada +7
The stellar initial mass function (IMF) plays a crucial role in determining the number of surviving stars in galaxies, the chemical composition of the interstellar medium, and the…
Prototype Implementation of Web and Desktop Applications for ALMA Science Verification Data and the Lessons Learned
Satoshi Eguchi, Wataru Kawasaki, Yuji Shirasaki +4
ALMA is estimated to generate TB scale data during only one observation; astronomers manage to identify which part of the data they are really interested in. Now we have been devel…
Extremely Metal-Poor Stars and a Hierarchical Chemical Evolution Model
Yutaka Komiya
Early phases of the chemical evolution and formation history of extremely metal poor (EMP) stars are investigated using hierarchical galaxy formation models. We build a merger tree…
The Stellar Abundances for Galactic Archaeology (SAGA) Database II - Implications for Mixing and Nucleosynthesis in Extremely Metal-Poor Stars and Chemical Enrichment of the Galaxy
Takuma Suda, Shimako Yamada, Yutaka Katsuta +4
We discuss the characteristics of known extremely metal-poor (EMP) stars in the Galaxy using the Stellar Abundances for Galactic Archaeology (SAGA) database (Suda et al. 2008, PASJ…
Formation History of Metal-Poor Halo Stars with Hierarchical Model and the Effect of ISM accretion on the Most Metal-Poor Stars
Yutaka Komiya, Asao Habe, Takuma Suda +1
We investigate the star formation and chemical evolution in the early universe by considering the merging history of the Galaxy in the ΛCDM scenario according to the extended Press…
Early-Age Evolution of the Milky Way Related by Extremely Metal-Poor Stars
Yutaka Komiya, Takuma Suda, Masayuki Y. Fujimoto
We exploit the recent observations of extremely metal-poor (EMP) stars in the Galactic halo and investigate the constraints on the IMF of the stellar population that left these low…
The Stellar Abundances for Galactic Archeology (SAGA) Database - Compilation of the Characteristics of Known Extremely Metal-Poor Stars
Takuma Suda, Yutaka Katsuta, Shimako Yamada +6
We describe the construction of a database of extremely metal-poor (EMP) stars in the Galactic halo whose elemental abundances have been determined. Our database contains detailed…
The Origin of Carbon-Enhancement and Initial Mass Function of Extremely Metal-Poor Stars in the Galactic Halo
Yutaka Komiya, Takuma Suda, Hiroki Minaguchi +3
It is known that the carbon-enhanced, extremely metal-poor (CEMP) stars constitute a substantial proportion in the extremely metal-poor (EMP) stars of the Galactic Halo, by far lar…