1.1k citations · 1.6k across the 23 of their papers we have counts for
7 papers · 1 filter
Photospheric carbon, nitrogen, and oxygen abundances of A-type main-sequence stars
Yoichi Takeda, Satoshi Kawanomoto, Naoko Ohishi +4
Based on the spectrum fitting method applied to CI 5380, NI 7486, and OI 6156-8 lines, we determined the abundances of C, N, and O for 100 mostly A-type main-sequence stars (late B…
Fourier analysis of He 4471/Mg 4481 line profiles for separating rotational velocity and axial inclination in rapidly-rotating B-type stars
Y. Takeda, S. Kawanomoto, N. Ohishi
While the effect of rotation on spectral lines is complicated in rapidly-rotating stars because of the appreciable gravity-darkening effect differing from line to line, it is possi…
On the Sodium versus Iron Correlation in Late B-Type Stars
Yoichi Takeda, Satoshi Kawanomoto, Naoko Ohishi
With an aim to study whether the close correlation between [Na/H] and [Fe/H] recently found in A-type stars further persists in the regime of B-type stars, the abundances of Na wer…
Detection of Low-Level Activities in Solar-Analog Stars from the Emission Strengths of Ca II 3934 Line
Yoichi Takeda, Akito Tajitsu, Satoshi Honda +3
Activity studies of solar-type stars, especially with reference to the status of our current Sun among them, have exposed the importance of (1) homogeneously selecting the sample s…
Lithium, Sodium, and Potassium Abundances in Sharp-Lined A-Type Stars
Yoichi Takeda, Dong-Il Kang, Inwoo Han +4
The abundances of alkali elements (Li, Na, and K) were determined from the Li I 6708, Na I 5682/5688, and K I 7699 lines by taking into account the non-LTE effect for 24 sharp-line…
Beryllium Abundances of Solar-Analog Stars
Yoichi Takeda, Akito Tajitsu, Satoshi Honda +3
An extensive beryllium abundance analysis was conducted for 118 solar analogs (along with 87 FGK standard stars) by applying the spectrum synthesis technique to the near-UV region…
Behavior of Li abundances in solar-analog stars II. Evidence of the connection with rotation and stellar activity
Y. Takeda, S. Honda, S. Kawanomoto +2
We previously attempted to ascertain why the Li I 6708 line-strengths of Sun-like stars differ so significantly despite the superficial similarities of stellar parameters. We carri…