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The determination of Li and proton-capture element abundances in globular cluster (GC) giants allows us to constrain several key questions on the multiple population scenarios in GCs, from formation and early evolution, to pollution and…

Solar and Stellar Astrophysics · Physics 2015-05-19 Valentina D'Orazi , Anna F. Marino

We discuss the high lithium abundances in the secondary stars of X-ray binaries. We show that no lithium production in these stars is necessary, and that the abundances can be explained simply due to the tidally locked rotation of the…

Astrophysics · Physics 2009-11-10 T. J. Maccarone , P. G. Jonker , A. I. Sills

The dependence of lithium abundance on modified gravity in low-mass stellar objects is demonstrated. This may introduce an additional uncertainty to age determination techniques of young stars and globular clusters if they rely on the light…

General Relativity and Quantum Cosmology · Physics 2021-02-24 Aneta Wojnar

Recent spectroscopic explorations of large Galactic stellar samples stars have revealed the existence of red giants with [$\alpha$/Fe] ratios that are anomalously high, given their relatively young ages. We revisit the GALAH DR3 survey to…

Solar and Stellar Astrophysics · Physics 2022-12-21 S. Borisov , N. Prantzos , C. Charbonnel

The recent discovery of low-mass red giants with enhanced atmospherical Li abundance in galactic low-metallicity stellar clusters adds to the mysterious phenomenon of the Li-rich giants. We propose a combined scenario for the Li-enrichment:…

Astrophysics · Physics 2007-05-23 P. A. Denissenkov , A. Weiss

The early-R stars are carbon-rich K-type giants. They are enhanced in C12, C13 and N14, have approximately solar oxygen, magnesium isotopes, s-process and iron abundances, have the luminosity of core-helium burning stars, are not rapid…

Astrophysics · Physics 2009-11-13 Robert G. Izzard , C. Simon Jeffery , John Lattanzio

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…

Astrophysics · Physics 2009-11-11 Ann Merchant Boesgaard , Megan C. Novicki , Alex Stephens

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…

Solar and Stellar Astrophysics · Physics 2015-05-13 O. A. Gonzalez , M. Zoccali , L. Monaco , V. Hill , S. Cassisi , D. Minniti , A. Renzini , B. Barbuy , S. Ortolani , A. Gomez

Lithium rich stars in globular clusters are rare. In fact, only 14 have been found so far, in different evolutionary phases from dwarfs to giants. Different mechanisms have been proposed to explain this enhancement, but it is still an open…

The presence of a large amount of Li in giants is still a mystery. Most of the super Li-rich giants reported in recent studies are in the solar metallicity regime. Here, we study the five metal-poor super Li-rich giants (SLRs) from GALAH…

Solar and Stellar Astrophysics · Physics 2024-03-26 Antony Susmitha , Anohita Mallick , Bacham E. Reddy

Carbon-enhanced metal-poor (CEMP) stars are believed to show the chemical imprints of more massive stars (M > 0.8 Msun) that are now extinct. In particular, it is expected that the observed abundance of Li should deviate in these stars from…

Solar and Stellar Astrophysics · Physics 2012-06-01 T. Masseron , J. A. Johnson , S. Lucatello , A. Karakas , B. Plez , T. C. Beers , N. Christlieb

I shall review what has been learnt during 20 years of lithium observations in stars belonging to metal-poor globular clusters. The focus will be on little evolved main-sequence, turnoff-point (TOP) and subgiant-branch (SGB) stars expected…

Solar and Stellar Astrophysics · Physics 2012-06-28 A. J. Korn

We find that hot jupiter host stars within the T$_\mathrm{eff}$ range 5900-6300K show lower Li abundances, by 0.14 dex, than stars without detected planets. This offset has a significance at the level 7$\sigma$, pointing to a stronger…

The surface lithium abundance A(Li) of warm metal-poor dwarf stars exhibits a narrow plateau down to [Fe/H]~-2.8 dex, while at lower metallicities the average value drops by 0.3 dex with a significant star-by-star scatter (called lithium…

Solar and Stellar Astrophysics · Physics 2022-06-01 A. Mucciarelli , L. Monaco , P. Bonifacio , M. Salaris , M. Deal , M. Spite , O. Richard , R. Lallement

Rotational velocity, lithium abundance, and the mass depth of the outer convective zone are key parameters in the study of the processes at work in the stellar interior, in particular when examining the poorly understood processes operating…

Solar and Stellar Astrophysics · Physics 2015-05-19 J. D. do Nascimento , J. S. da Costa , J. R. De Medeiros

Among stars in Galactic globular clusters the carbon abundance tends to decrease with increasing luminosity on the upper red giant branch, particularly within the lowest metallicity clusters. While such a phenomena is not predicted by…

Solar and Stellar Astrophysics · Physics 2019-04-08 Jeffrey M. Gerber , Michael M. Briley , Graeme H. Smith

In this paper we report two new super Li-rich K giants: KIC 2305930 and KIC 12645107 with Li abundances exceeding that of ISM (A(Li) $\geq$ 3.2 dex). Importantly, both the giants have been classified as core He-burning red clump stars based…

Solar and Stellar Astrophysics · Physics 2018-05-23 Yerra Bharat Kumar , Raghubar Singh , B. Eswar Reddy , Gang Zhao

Using observations of rapidly rotating roAp star HD 12098, obtained with 6m telescope of SAO RAS in 2005-2008 in nine rotational phases (0.001-0.817), and code V. Tsymbal ROTATE we identified 3 lithium spots on the surface of star, one of…

Solar and Stellar Astrophysics · Physics 2013-04-16 A. Shavrina , N. S. Polosukhina , N. A. Drake , D. O. Kudryavtsev , V. F. Gopka , V. A. Yushchenko , A. V. Yushchenko

I summarize the stellar side of the cosmological lithium problem(s). Evidence from independent studies is accumulating and indicates that stars may very well be fully responsible for lowering their surface lithium from the predicted…

Solar and Stellar Astrophysics · Physics 2024-06-17 A. J. Korn

A non-LTE analysis of K I resonance lines at 7664.91 and 7698.97 A was carried out for 15 red giants belonging to three globular clusters of different metallicity (M 4, M 13, and M 15) along with two reference early-K giants (rho Boo and…

Solar and Stellar Astrophysics · Physics 2015-05-13 Y. Takeda , H. Kaneko , N. Matsumoto , S. Oshino , H. Ito , T. Shibuya