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Lithium depletion in solar-like stars: no planet connection
We have determined precise stellar parameters and lithium abundances ina sample of 117 stars with basic properties very similar to the Sun.This sample selection reduces biasing effects and systematic errors inthe analysis. We estimate the ages of our sample stars mainly fromisochrone fitting but also from measurements of rotation period andX-ray luminosity and test the connection between lithium abundance, age,and stellar parameters. We find strong evidence for increasing lithiumdepletion with age. Our sample includes 14 stars that are known to hostplanets and it does not support recent claims that planet-host starshave experienced more lithium depletion than stars without planets. Wefind the solar lithium abundance normal for a star of its age, mass, andmetallicity. Furthermore, we analyze published data for 82 stars thatwere reported to support an enhanced lithium depletion in planet hosts.We show that those stars in fact follow an age trend very similar tothat found with our sample and that the presence of giant planets is notrelated to low lithium abundances. Finally, we discuss the systematicbiases that led to the incorrect conclusion of an enhanced lithiumdepletion in planet-host stars.
| Accurate abundance patterns of solar twins and analogs. Does the anomalous solar chemical composition come from planet formation?
We derive the abundance of 19 elements in a sample of 64 stars withfundamental parameters very similar to solar, which minimizes the impactof systematic errors in our spectroscopic 1D-LTE differential analysis,using high-resolution (R?60 000), high signal-to-noise ratio(S/N?200) spectra. The estimated errors in the elemental abundancesrelative to solar are as small as ?0.025 dex. The abundance ratios[X/Fe] as a function of [Fe/H] agree closely with previously establishedpatterns of Galactic thin-disk chemical evolution. Interestingly, themajority of our stars show a significant correlation between [X/Fe] andcondensation temperature (T_C). In the sample of 22 stars withparameters closest to solar, we find that, on average, low TCelements are depleted with respect to high TC elements in thesolar twins relative to the Sun by about 0.08 dex (?20%). Anincreasing trend is observed for the abundances as a function ofTC for 900
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Osservazione e dati astrometrici
| Costellazione: | Orsa Maggiore |
| Ascensione retta: | 09h23m39.60s |
| Declinazione: | +66°08'14.1" |
| Magnitudine apparente: | 8.929 |
| Distanza: | 65.147 parsec |
| Moto proprio RA: | -83.7 |
| Moto proprio Dec: | -75.4 |
| B-T magnitude: | 9.721 |
| V-T magnitude: | 8.995 |
Cataloghi e designazioni:
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