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A High-Resolution Spectrum of the Extremely Metal-rich Bulge G Dwarf OGLE-2006-BLG-265
We present an R=45,000 Keck spectrum of the microlensed Galactic bulge Gdwarf OGLE-2006-BLG-265, which has high (~60) signal-to-noise ratiodespite its short (15 minute) exposure time, because the source wasmagnified by A~135. While it is very metal-rich ([Fe/H]=0.56), thehigher temperature of this star compared with the luminous red giantsusually measured in the bulge gives its spectrum many unblended atomiclines. We measure the abundances of 17 elements, including the firstabundances for S and Cu in a bulge star. The [?/Fe] ratios aresubsolar, while the odd-Z elements are slightly supersolar, trends thatare also seen in the more metal-rich stars in the bulge and the localGalactic disk. Because the star is a dwarf, the [O/Fe], [Na/Fe], and[Al/Fe] ratios cannot be attributed to internal mixing, as is sometimesclaimed for giants. Similar high-resolution spectra could be obtainedfor about a dozen bulge dwarf stars per year by means of well-designedtarget-of-opportunity observations.The data presented here were obtained at the W. M. Keck Observatory,which is operated as a scientific partnership among the CaliforniaInstitute of Technology, the University of California, and the NationalAeronautics and Space Administration. The Observatory was made possibleby the generous financial support of the W. M. Keck Foundation.
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Pozíciós és asztrometriai adatok
| Csillagkép: | Sas |
| Rektaszcenzió: | 23h41m45.38s |
| Deklináció: | -20°10'14.4" |
| Vizuális fényesség: | 8.312 |
| Távolság: | 636.943 parszek |
| RA sajátmozgás: | -5.5 |
| Dec sajátmozgás: | -9 |
| B-T magnitude: | 10.014 |
| V-T magnitude: | 8.453 |
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