82 citations · 169 across the 6 of their papers we have counts for
6 papers
On the photospheric abundances of the B-type fast rotator Regulus
Yoichi Takeda
A spectroscopic study of Regulus (late B-type rapidly-rotating star) was conducted with an aim of investigating its photospheric chemical abundances (especially for light elements)…
Photospheric abundances of the rapidly-rotating A-type star Altair
Yoichi Takeda
Altair is an A-type star known to have an appreciably oblate shape owing to its very fast rotation (~300 km/s). Despite of numerous publications on this star, its chemical abundanc…
Fundamental stellar parameters and age-metallicity relation of Kepler red giants in comparison with theoretical evolutionary tracks
Y. Takeda, A. Tajitsu, B. Sato +3
Spectroscopic parameters (effective temperature, metallicity, etc) were determined for a large sample of ~100 red giants in the Kepler field, for which mass, radius, and evolutiona…
C, N, O, and Na Abundances of Cepheid Variables: Implications on the Mixing Process in the Envelope
Y. Takeda, D. -I. Kang, I. Han +2
With an aim of investigating the nature of evolution-induced mixing in the envelope of evolved intermediate-mass stars, we carried out an extensive spectroscopic study for 12 Cephe…
Potassium Abundances in Red Giants of Mildly to Very Metal-Poor Globular Clusters
Y. Takeda, H. Kaneko, N. Matsumoto +3
A non-LTE analysis of K I resonance lines at 7664.91 and 7698.97 A was carried out for 15 red giants belonging to three globular clusters of different metallicity (M 4, M 13, and M…
Non-LTE Analysis for the Sodium Abundances of Metal-Poor Stars in the Galactic Disk and Halo
Yoichi Takeda, Gang Zhao, Masahide Takada-Hidai +3
We performed an extensive non-LTE analysis of the neutral sodium lines of Na {\sc i} 5683/5688, 5890/5896, 6154/6161, and 8183/8195 for disk/halo stars of F--K type covering a wide…