The Penn State - Torun Centre for Astronomy Planet Search stars. II. Lithium abundance analysis of the Red Giant Clump sample

Abstract

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 investigate various channels of Li enrichment in giants. Our work is based on the HET/HRS spectra. The A(Li) was determined from the 670.8nm line, while we use a more extended set of lines for alpha-elements abundances. In a series of K-S tests, we compare Li-rich giants with other stars in the sample. We also use available IR photometric and kinematical data in search for evidence of mass-loss. We investigate properties of the most Li-abundant giants in more detail by using multi-epoch precise radial velocities. We present Li and alpha-elements abundances, as well as vsini for 348 stars. We detected Li in 92 stars, of which 82 are giants. 11 of them show significant Li abundance A(Li)>1.4 and 7 of them are Li-overabundant objects, according to criterion of A(Li)>1.5 and their location on HR diagram, including two giants with Li abundances close to meteoritic level. For another 271 stars, upper limits of A(Li) are presented. We show that Li-rich giants are among the most massive stars from our sample and show larger than average effective temperatures. They are indistinguishable from the complete sample in terms of their distribution of luminosity, [Fe/H], vsini, and alpha-elements abundances. Our results do not point out to one specific Li enrichment mechanism operating in our sample of giants. On the contrary, in some cases, we cannot identify fingerprints of any of known scenarios. We show, however, that the 4 most Li-rich giant in our sample either have low-mass companions or have RV variations at the level of ~100 m/s, which strongly suggests that the presence of companions is an important factor in the Li-enrichment processes in giants.

Accepted for publication in A&A, 13 figures, 11 tables, 26 pages

References in corpus (11)

• Scaled solar tracks and isochrones in a large region of the Z-Y plane I. From the ZAMS to the TP-AGB end for 0.15 - 2.5 Mo stars
• Thermohaline mixing: A physical mechanism governing the photospheric composition of low-mass giants
• Precise radial velocities of giant stars. III. Spectroscopic stellar parameters
• Oxygen Abundances in Nearby Stars. Clues to the formation and evolution of the Galactic disk
• Can Extra Mixing in RGB and AGB Stars Be Attributed to Magnetic Mechanisms?
• Observable Signatures of Planet Accretion in Red Giant Stars I: Rapid Rotation and Light Element Replenishment
• A Planetary Mass Companion to the K0 Giant HD 17092
• The Role of Planet Accretion in Creating the Next Generation of Red Giant Rapid Rotators
• Rotation and Macroturbulence in Metal-poor Field Red Giant and Red Horizontal Branch Stars
• Lithium Abundances in a Sample of Planet Hosting Dwarfs
• The Super Lithium-Rich Red Giant Rapid Rotator G0928+73.2600: A Case for Planet Accretion?

Cited by in corpus (11)

• A Comparison of Stellar Elemental Abundance Techniques and Measurements
• Star-planet interactions: II. Is planet engulfment the origin of fast rotating red giants?
• The orbital evolution of asteroids, pebbles and planets from giant branch stellar radiation and winds
• Lithium-rich Giants in LAMOST Survey. I. The Catalog
• Population synthesis of helium white dwarf--red giant star mergers and the formation of lithium-rich giants and carbon stars
• Three red giants with substellar-mass companions
• Tracking Advanced Planetary Systems with HARPS-N (TAPAS). I. A multiple planetary system around the red giant star TYC 1422-614-1
• Far-infrared study of K giants in the solar neighborhood: Connection between Li enrichment and mass-loss
• On Lithium-6 as diagnostic of the lithium-enrichment mechanism in red giants
• Gemini-GRACES high-quality spectra of Kepler evolved stars with transiting planets I. Detailed characterization of multi-planet systems Kepler-278 and Kepler-391
• Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. V.: A Massive Jupiter orbiting the very low metallicity giant star BD+03 2562 and a possible planet around HD~103485