Y. Takeda

Publications195
h-index34
Citations3,958
Highly Influential Citations550
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Non-LTE Line-Formation and Abundances of Sulfur and Zinc in F, G, and K Stars
Extensive statistical-equilibrium calculations on neutral sulfur and zinc were carried out, in order to investigate how the non-LTE effect plays a role in the determination of S and Zn abundances in…
Oxygen line formation in late-F through early-K disk/halo stars. Infrared O I triplet and [O I] lines
In order to investigate the formation of O  7771-5 and (O ) 6300/6363 lines, extensive non-LTE calculations for neutral atomic oxygen were carried out for wide ranges of model atmosphere…
Stellar Parameters and Elemental Abundances of Late-G Giants
The properties of 322 intermediate-mass late-G giants (comprising 10 planet-host stars) selected as the targets of the Okayama Planet Search Program, many of which are red-clump giants, were…
Photospheric CNO Abundances of Solar-Type Stars
We determined the C, N, and O abundances of 160 nearby F, G, and K dwarfs and subgiants by using spectra obtained with the HIDES spectrograph at Okayama Astrophysical Observatory, with the purposes…
Planetary Companions around Three Intermediate-Mass G and K Giants: 18 Delphini, ξ Aquilae, and HD 81688
We report on the detection of 3 new extrasolar planets from a precise Doppler survey of G and K giants at Okayama Astrophysical Observatory. The host stars, 18 Del (G6 III), � Aql (K0 III) and HD…
Fundamental Parameters and Elemental Abundances of 160 F-G-K Stars Based on OAO Spectrum Database
The properties of 160 F, G, and K disk dwarfs/subgiants (including 27 planet-host stars) mostly within � 0:6 . [Fe/H] . +0:4 ,t he Okayama Astrophysical Observatory spectrum collection of which had…
Non-LTE Analysis of the Sodium Abundance of Metal-Poor Stars in the Galactic Disk and Halo
We performed an extensive non-LTE analysis of the neutral sodium lines of Na i 5683/5688, 5890/5896, 6154/6161, and 8183/8195 in disk/halo stars of types F-K covering a wide metallicity range ( 4 <…
A Planetary Companion to the Hyades Giant ∊ Tauri
Wereportthedetection of anextrasolarplanet orbitingTau,oneof thegiantstarsintheHyadesopencluster.This is the first planet ever discovered in an open cluster. Precise Doppler measurements of this star…
Spectroscopic Study on the Atmospheric Parameters of Nearby F-K Dwarfs and Subgiants
Based on a collection of high-dispersion spectra obtained at Okayama Astrophysical Observatory, the atmospheric parameters (Teff ,l ogg, vt ,a nd [Fe/H]) of 160 mid-F through early-K stars were…
Lithium Abundances of F-, G-, and K-Type Stars: Profile-Fitting Analysis of the Li I 6708 Doublet
An extensive profile-fitting analysis was performed for the Li(+Fe) 6707–6708 u A feature of nearby 160 F–K dwarfs/subgiants (including 27 planet-host stars) in the Galactic disk (7000K Teff5000K,…
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