842 citations · 3.5k across the 66 of their papers we have counts for
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Revealing α-Element's Past with Subaru/IRD: Oxygen Abundance of 35 Very Metal-Poor Stars from Near-IR OH lines
Bakuh Danang Setyo Budi, Wako Aoki, Nicholas Storm +10
Oxygen abundances in very and extremely metal-poor (V/EMP) stars provide critical constraints on early massive stars' nucleosynthesis. An Oxygen abundance analysis is presented for…
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…
Th/Eu abundance ratio of red giants in the Kepler Field
Ainun Azhari, Tadafumi Matsuno, Wako Aoki +2
The r-process production in the early universe has been well constrained by the extensive studies of metal-poor stars. However, the r-process enrichment in the metal-rich regime is…
Four-hundred Very Metal-Poor Stars Studied with LAMOST and Subaru. II. Elemental abundances
Haining Li, Wako Aoki, Tadafumi Matsuno +9
We present homogeneous abundance analysis of over 20 elements for 385 very metal-poor (VMP) stars based on the LAMOST survey and follow-up observations with the Subaru Telescope. I…
Four-hundred Very Metal-poor Stars studied with LAMOST and Subaru. I. Survey Design, Follow-up Program, and Binary Frequency
Wako Aoki, Haining Li, Tadafumi Matsuno +11
The chemical abundances of very metal-poor stars provide important constraints on the nucleosynthesis of the first generation of stars and early chemical evolution of the Galaxy. W…
Star Formation Timescales of the Halo Populations from Asteroseismology and Chemical Abundances
Tadafumi Matsuno, Wako Aoki, Luca Casagrande +9
We combine asteroseismology, optical high-resolution spectroscopy, and kinematic analysis for 26 halo red giant branch stars in the \textit{Kepler} field in the range of $-2.5<[\ma…
Inferring the velocity of early massive stars from the abundances of extremely metal-poor stars
Arthur Choplin, Nozomu Tominaga, M. N. Ishigaki
The nature of the first massive stars may be inferred by investigating the origin of the extremely metal-poor (EMP) stars, likely formed from the ejecta of one or a few previous ma…
Evidence for the accretion origin of halo stars with an extreme r-process enhancement
Qian-Fan Xing, Gang Zhao, Wako Aoki +4
Small stellar systems like dwarf galaxies are suggested to be the main building blocks of our Galaxy by numerical simulations in Lambda CDM models. The existence of star streams li…
Evidence for an aspherical Population III supernova explosion inferred from the hyper metal-poor star HE1327-2326
Rana Ezzeddine, Anna Frebel, Ian U. Roederer +6
We present observational evidence that an aspherical supernova explosion could have occurred in the First stars in the early universe. Our results are based on the First determinat…
Line identification and photometric history of the hot post-AGB star Hen 3-1013 (IRAS 14331-6435)
V. P. Arkhipova, M. Parthasarathy, N. P. Ikonnikova +4
We present a study of the high-resolution optical spectrum for the hot post-asymptotic giant branch (post-AGB) star, Hen 3-1013, identified as the optical counterpart of the infrar…
LAMOST J2217+2104: a new member of carbon-enhanced extremely metal-poor stars with excesses of Mg and Si
Wako Aoki, Tadafumi Matsuno, Satoshi Honda +4
We report on the elemental abundances of the carbon-enhanced metal-poor (CEMP) star J2217+2104 discovered by our metal-poor star survey with LAMOST and Subaru. This object is a red…
Optical high-resolution spectroscopy of 14 young -rich stars
Tadafumi Matsuno, David Yong, Wako Aoki +1
We report chemical abundances of 14 young -rich stars including neutron-capture elements based on high-quality optical spectra from HIRES/Keck I and differential line-by-line an…
The Initial mass function of the first stars inferred from extremely metal-poor stars
Miho N. Ishigaki, Nozomu Tominaga, Chiaki Kobayashi +1
We compare elemental abundance patterns of extremely metal-poor (EMP; [Fe/H]) stars with supernova yields of metal-free stars in order to obtain insights into the c…
Enrichment in r-process elements from multiple distinct events in the early Draco dwarf spheroidal galaxy
Takuji Tsujimoto, Tadafumi Matsuno, Wako Aoki +2
The stellar record of elemental abundances in satellite galaxies is important to identify the origin of r-process because such a small stellar system could have hosted a single r-p…
Multicolor light curves simulations of Population III core-collapse supernovae: from shock breakout to Co decay
Alexey Tolstov, Ken'ichi Nomoto, Nozomu Tominaga +3
The properties of the first generation of stars and their supernova (SN) explosions remains unknown due to the lack of their actual observations. Recently many transient surveys ar…
Sodium Absorption Systems toward SN Ia 2014J Originate on Interstellar Scales
K. Maeda, A. Tajitsu, K. S. Kawabata +21
Na I D absorbing systems toward Type Ia supernovae (SNe Ia) have been intensively studied over the last decade with the aim of finding circumstellar material (CSM), which is an ind…
Type IIb Supernova 2013df Entering Into An Interaction Phase: A Link between the Progenitor and the Mass Loss
K. Maeda, T. Hattori, D. Milisavljevic +23
We report the late-time evolution of Type IIb Supernova (SN IIb) 2013df. SN 2013df showed a dramatic change in its spectral features at ~1 year after the explosion. Early on it sho…
The Chemical composition of the post-AGB F-supergiant CRL 2688
Miho N. Ishigaki, Mudumba Parthasarathy, Bacham E. Reddy +5
We present an analysis of a high resolution (R~50,000) optical spectrum of the central region of the proto-planetary nebula CRL 2688. This object is thought to have recently moved…