Sulphur in the metal poor globular cluster NGC 6397
نویسندگان
چکیده
منابع مشابه
Photometry of Variable Stars in the Globular Cluster NGC 6397
Time series BV I photometry is presented for 16 short-period variables located in the central region of the globular cluster NGC 6397. The sample includes 9 newly detected variables. The light curve of cataclysmic variable CV6 shows variability with a period of 0.2356 days. We confirm an earlier reported period of 0.472 days for cataclysmic variable CV1. Phased light curves of both CVs exhibit ...
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Context. To alleviate the discrepancy between the prediction of the primordial lithium abundance in the universe and the abundances observed in Pop II dwarfs and subgiant stars, it has been suggested that the stars observable today have undergone photospheric depletion of lithium. Aims. To identify the cause of this depletion, it is important to accurately establish the behaviour of lithium abu...
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High-resolution échelle spectra of five giants and eleven subgiants of the metal-poor globular cluster NGC 6397 were obtained at the ESO 3.5m (NTT) and 3.6m telescopes. A detailed analysis of the 16 sample stars was carried out, providing atmospheric parameters (Teff , log g, [Fe/H], vt) and element abundances. The metallicity of the cluster is [Fe/H] = −2.0 with a r.m.s. of ±0.05, irrespective...
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We present spectroscopic and photometric observations of the eclipsing binary V32 located in the central field of the globular cluster NGC 6397. The variable is a single-line spectroscopic binary with an orbital period of 9.8783 d and a large eccentricity of e = 0.32. Its systemic velocity (γ = 20.7 km s) and metallicity ([Fe/H] ∼ -1.9) are both consistent with cluster membership. The primary c...
متن کاملL etter to the E ditor Lithium in the Globular Cluster NGC 6397 ⋆
Context. The lithium abundance predicted by the standard big bang nucleosynthesis with the baryonic density accurately measured from the fluctuations of the cosmic microwave background is a factor of three higher than that observed in metal-poor dwarf stars of the Galactic halo, the so-called Spite Plateau. Most Globular Clusters are believed to host a single stellar populations. They can thus ...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2011
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361/201117678