相关论文: Lithium in Open Cluster Red Giants Hosting Substel…

The aim of this work is to search for Li-rich giants in a sample of clusters where planets have been searched, thus we can study the planet engulfment scenario to explain Li replenishment using a proper comparison sample of stars without…

A small fraction of red giants are known to be lithium (Li) rich, in contradiction with expectations from stellar evolutionary theory. A possible explanation for these atypical giants is the engulfment of a Li-rich planet or brown dwarf by…

It has recently been suggested that all giant stars with mass below 2 $M_{\odot}$ suffer an episode of surface lithium enrichment between the tip of the red giant branch (RGB) and the red clump (RC). We test if the above result can be…

The Gaia-ESO survey recently reported on a large sample of lithium (Li) abundance determinations for evolved stars in the rich open cluster Trumpler 20. They argue for a scenario where virtually all stars experience post main sequence…

Lithium-rich red giants have been a long-standing mystery in stellar astrophysics. A leading theory to explain these chemically peculiar and rare objects is interactions with a close companion. To investigate their companion fraction, we…

Although not predicted by standard stellar evolution, the surface abundance of light elements, such as lithium (Li), carbon, and nitrogen, changes during the red giant branch (RGB) as a result of extra-mixing. This is associated usually…

The orders of magnitude variation in lithium abundances of evolved stars have long been a puzzle. Diluted signals, ambiguous evolutionary states and unknown masses have made it challenging to both map the expected lithium signals and…

To understand the underlying mechanisms for high lithium abundances among core He-burning or red clump (RC) giants, we analyzed a sample of 5227 RC giants of mass M $\leq$ 2~M$_{\odot}$ using spectra and asteroseismic data. We found 120 RC…

Open clusters serve as laboratories to study and evaluate stellar evolution and Galactic chemical evolution models. Chemical peculiarities, such as lithium-rich giants, are rarely observed in these stellar systems. This work focuses on…

A Li-rich red giant star (2M19411367+4003382) recently discovered in the direction of NGC 6819 belongs to the rare subset of Li-rich stars that have not yet evolved to the luminosity bump, an evolutionary stage where models predict Li can…

Using the sample of 348 stars from the PennState-Torun Centre for Astronomy Planet Search, for which uniformly determined atmospheric parameters are available, with chemical abundances and rotational velocities presented here, we…

The temperature distribution of field Li-rich red giants suggests the presence of a population of Li-rich red clump (RC) stars. One proposed explanation for this population is that all stars with masses near 2 $M_\odot$ experience a…

With an aim to shed light on the origin of Li anomaly observed in a small fraction of red giants, we carried out a spectroscopic study on the observational characteristics of selected 20 bright Li-rich giants, in comparison with a large…

Lithium is extensively known to be a good tracer of non-standard mixing processes occurring in stellar interiors. We present the results of a new large Lithium survey in red giant stars and combine it with surveys from the literature to…

We present FLAMES/GIRAFFE spectroscopy obtained at the Very Large Telescope (VLT). Using these observations we have been able for the first time to observe the Li I doublet in the Main Sequence stars of a Globular Cluster. We also observed…

Thanks to the high multiplex and efficiency of Giraffe at the VLT we have been able for the first time to observe the Li I doublet in the Main Sequence (MS) stars of a Globular Cluster. At the same time we observed Li in a sample of…

High lithium-7 ($\mathrm{^7Li}$) abundances in giants are indicative of non-standard physical processes affecting the star. Mechanisms that could produce this signature include contamination from an external source, such as planets, or…

We have gathered optical-region spectra, derived model atmosphere parameters, and computed elemental abundances for 15 red giant stars in the open cluster NGC 7789. We focus on the light element group CNOLi that provides clues to…

We present a chemical abundance study of giant stars in the Galactic open cluster NGC 5822, which hosts two barium stars (#002 and #201) and three lithium-enriched giants (#006, #102, and #240). Using high-resolution optical and…

Stellar models predict that lithium (Li) inside a star is destroyed during the first dredge-up phase, yet 1.2% of red giant stars are Li-rich. We aim to uncover possible origins of this population, by analysing 1155 Li-rich giants (A(Li)…