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We present a study on the detailed elemental abundances of newly identified bright very metal-poor stars with the detection of lithium, initially observed as part of the SDSS/MARVELS pre-survey. These stars were selected for high-resolution…

太阳与恒星天体物理 · 物理学 2022-10-05 Avrajit Bandyopadhyay , Thirupathi Sivarani , Timothy C. Beers , A. Susmitha , Prasanta K Nayak , Jeewan C Pandey

We test a scenario in which radial migration could affect the Li abundance pattern of dwarf stars in the solar neighbourhood. This may confirm that the Li abundance in these stars can not serve as a probe for the Li abundance in the…

The application to main-sequence stars of the rotation-induced mixing theory in the presence of mu-gradients leads to partial mixing in the lithium destruction region, not visible in the atmosphere. The induced lithium depletion becomes…

天体物理学 · 物理学 2007-05-23 Jose Dias do Nascimento , Sylvie Theado , Sylvie Vauclair

The measurement of the cosmic microwave background has strongly constrained the cosmological parameters of the Universe. When the measured density of baryons (ordinary matter) is combined with standard Big Bang nucleosynthesis calculations,…

天体物理学 · 物理学 2009-11-11 A. J. Korn , F. Grundahl , O. Richard , P. S. Barklem , L. Mashonkina , R. Collet , N. Piskunov , B. Gustafsson

Lithium abundances are presented for 91 dwarf and subgiant stars in the Galactic bulge. The analysis is based on line synthesis of the 7Li line at 6707 {\AA} in high-resolution spectra obtained during gravitational microlensing events, when…

星系天体物理 · 物理学 2020-02-26 T. Bensby , S. Feltzing , J. C. Yee , J. A. Johnson , A. Gould , M. Asplund , J. Meléndez , S. Lucatello

The light element lithium is formed by nucleosynthesis during the Big Bang. Its abundance can help to define the parameters of the early universe. To find this primordial value, it is necessary to determine Li abundances in the oldest stars…

太阳与恒星天体物理 · 物理学 2023-07-28 Ann Merchant Boesgaard , Constantine P. Deliyannis

The Li-rich stars are a class of rare objects with A(Li) higher than that of other stars in the same evolutionary stage. Their origin is still debated and valuable routes are the Cameron-Fowler mechanism, mass transfer process in a binary…

太阳与恒星天体物理 · 物理学 2024-09-04 A. Mucciarelli , P. Bonifacio , L. Monaco , M. Salaris , M. Matteuzzi

We present Lithium abundance determination for a sample of K giant stars in the galactic bulge. The stars presented here are the only 13 stars with detectable Lithium line (6767.18 A) among ~400 stars for which we have spectra in this…

太阳与恒星天体物理 · 物理学 2015-05-13 O. A. Gonzalez , M. Zoccali , L. Monaco , V. Hill , S. Cassisi , D. Minniti , A. Renzini , B. Barbuy , S. Ortolani , A. Gomez

We derive atmospheric parameters and lithium abundances for 671 stars and include our measurements in a literature compilation of 1381 dwarf and subgiant stars. First, a "lithium desert" in the effective temperature (Teff) versus lithium…

太阳与恒星天体物理 · 物理学 2015-06-05 I. Ramirez , J. R. Fish , D. L. Lambert , C. Allende Prieto

Preliminary abundances of lithium and a few other elements have been obtained for 31 field Am stars with good Hipparcos parallaxes, as well as for 36 normal A and F stars. Radial and projected rotational velocities were determined as well.…

天体物理学 · 物理学 2009-11-11 P. North , F. Betrix , C. Besson

Lithium abundances have been determined in more than 100 metal-poor halo stars both in the field and in clusters. From these data we find trends of Li with both temperature and metallicity and a real dispersion in Li abundances in the Spite…

天体物理学 · 物理学 2009-11-11 Ann Merchant Boesgaard , Megan C. Novicki , Alex Stephens

Lithium abundances are presented for a sample of 181 nearby F and G dwarfs with accurate {\it Hipparcos} parallaxes. The stars are on circular orbits about the Galactic centre and, hence, are identified as belonging to the thin disk. This…

天体物理学 · 物理学 2009-11-10 David L. Lambert , Bacham E. Reddy

We have measured stellar parameters, [Fe/H], lithium abundances, rotation, and 12C/13C in a small sample of red giants in three open clusters that are each home to a red giant star that hosts a substellar companion (NGC2423 3, NGC4349 127,…

太阳与恒星天体物理 · 物理学 2016-02-17 Joleen K. Carlberg , Verne V. Smith , Katia Cunha , Kenneth G. Carpenter

Recent dramatic improvements in the modeling of abundance evolution due to diffusion in A stars have been achieved with the help of monochromatic opacity tables from the OPAL group. An important result in the context of stellar pulsations…

天体物理学 · 物理学 2007-05-23 S. Turcotte , J. Richer , G. Michaud , J. Christensen-Dalsgaard

We present NLTE Li abundances for 88 stars in the metallicity range -3.5 < [Fe/H] < -1.0. The effective temperatures are based on the infrared flux method with improved E(B-V) values obtained mostly from interstellar NaI D lines. The Li…

太阳与恒星天体物理 · 物理学 2015-05-19 Jorge Melendez , Luca Casagrande , Ivan Ramirez , Martin Asplund , William Schuster

Lithium and zirconium abundances (the latter taken as representative for s-process enrichment) are determined for a large sample of massive Galactic O-rich AGB stars, for which high resolution optical spectroscopy has been obtained…

天体物理学 · 物理学 2009-11-11 D. A. Garcia-Hernandez , P. Garcia-Lario , B. Plez , A. Manchado , F. D'Antona , J. Lub , H. Habing

The source of the Galactic Lithium (Li) has long been a puzzle. With the discovery of Li in novae, extensive research has been conducted. However, there still exists a significant disparity between the observed abundance of lithium in novae…

太阳与恒星天体物理 · 物理学 2024-06-25 Jun Gao , Chunhua Zhu , Guoliang Lü , Jinlong Yu , Lin Li , Helei Liu , Sufen Guo

I summarize the results of 15 years of research on the surface abundances of stars in globular clusters. Globular-cluster stars afford a unique view of the physical processes that shape the surface abundances of stars on and beyond the…

太阳与恒星天体物理 · 物理学 2021-11-02 A. J. Korn

The depletion of lithium during the pre-main sequence and main sequence phases of stellar evolution plays a crucial role in the comparison of the predictions of big bang nucleosynthesis with the abundances observed in halo stars. In the…

天体物理学 · 物理学 2011-05-05 M. H. Pinsonneault , T. P. Walker , G. Steigman , V. K. Narayanan

We report on the abundance analysis of Li in solar-type (G-type main sequence) superflare stars which were found by the analysis of Kepler photometric data. Li is a key element to understand the evolution of the stellar convection zone…

太阳与恒星天体物理 · 物理学 2015-07-15 Satoshi Honda , Yuta Notsu , Hiroyuki Maehara , Shota Notsu , Takuya Shibayama , Daisaku Nogami , Kazunari Shibata