THE HELIUM ABUNDANCE IN THE METAL-POOR GLOBULAR CLUSTERS M30 AND NGC 6397
نویسندگان
چکیده
منابع مشابه
High resolution abundance analysis of 16 giants and subgiants in the metal - poor globular cluster NGC 6397 ?
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...
متن کاملThe peculiar millisecond pulsars in the globular clusters NGC 6397 and NGC 6752
The millisecond pulsars discovered in globular clusters are diagnostic tools for studying the dynamics of the clusters, the intracluster ionized gas and the evolution of the binaries embedded in the cluster. In the first two years of a search at 1.4 GHz in progress at the Parkes radio telescope 12 new millisecond pulsars have been discovered in 6 globular clusters in which no pulsars were previ...
متن کاملChemical Abundances of Three Metal-poor Globular Clusters (ngc 6287, Ngc 6293, and Ngc 6541) in the Inner Halo
We present a chemical abundance study of three inner old halo clusters NGC 6287, NGC 6293, and NGC 6541, finding [Fe/H] = −2.01 ± 0.05, −1.99 ± 0.02, and −1.76 ± 0.02 (internal), respectively, and our metallicity measurements are in good agreement with previous estimates. We also present the radial velocity measurements of the clusters. Our radial velocity measurements for NGC 6293 and NGC 6541...
متن کاملSignatures of intrinsic Li depletion and Li - Na anti - correlation in the metal - poor globular cluster NGC 6397 ⋆ , ⋆ ⋆
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...
متن کاملV I Photometry of Globular Clusters Ngc 6293 and Ngc 6541: the Formation of the Metal-poor Inner Halo Globular Clusters
We present V I photometry of the metal-poor inner halo globular clusters NGC 6293 and NGC 6541 using the planetary camera of the WFPC2 on board Hubble Space Telescope (HST). Our color-magnitude diagrams of the clusters show well-defined blue horizontal branch (BHB) populations, consistent with their low metallicities and old ages. NGC 6293 appears to have blue straggler stars in the cluster’s c...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2014
ISSN: 0004-637X,1538-4357
DOI: 10.1088/0004-637x/786/1/14