| Issue |
A&A
Volume 468, Number 2, June III 2007
The XMM-Newton extended survey of the Taurus molecular cloud
|
|
|---|---|---|
| Page(s) | 663 - 677 | |
| Section | Stellar atmospheres | |
| DOI | https://doi.org/10.1051/0004-6361:20077220 | |
| Published online | 29 March 2007 | |
Behavior of Li abundances in solar-analog stars*,**
Evidence for line-width dependence
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan e-mail: takedayi@cc.nao.ac.jp
Received:
2
February
2007
Accepted:
5
March
2007
Context.It is known that the surface lithium abundances
of field solar-analog G dwarfs show a large
dispersion of 
2 dex (among which our Sun is
located at the lower end) despite the similarity of
stellar parameters, and planet-host stars tend to show
comparatively lower Li abundances in the narrow Teff range.
Aims.To investigate the reason for these phenomena, an extensive study of Li abundances and their dependence on stellar parameters was carried out for a homogeneous sample of 118 selected solar analogs based on high-dispersion spectra obtained at Okayama Astrophysical Observatory.
Methods.The atmospheric parameters were spectroscopically determined by using the equivalent widths of Fe i and Fe ii lines, the ages/masses were estimated from stellar evolutionary tracks, and the width of the macrobroadening (rotation plus macroturbulence) function as well as Li abundances (ALi) were established by spectrum-fitting analyses.
Results.The resulting ALi vs. Teff relation
revealed a characteristic inverse-triangle-like distribution
enclosed by two clear-cut boundaries (the slanted one running from ~5900 K to ~5800 K and the vertical one at ~5700 K), while the Sun is located
around its lowest apex. More significantly, ALi in this
region of large dispersion was found to closely correlate
with the macrobroadening width 
, which is considered
to be the most important parameter.
Conclusions.With a reasonable assumption that the difference of rotational velocity is mainly responsible for the variety of vr+m, we may conclude that the stellar angular momentum plays the decisive role in determining the surface Li abundances of solar-analog stars in the Teff range of ~5900–5700 K. The low-Li tendency of planet-host stars may thus be interpreted in terms of rotational characteristics.
Key words: stars: abundances / stars: atmospheres / stars: fundamental parameters / stars: late-type / Sun: fundamental parameters
© ESO, 2007
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