Lithium in the active sub-giant HD123351. A quantitative analysis with 3D and 1D model atmospheres using different observed spectra

Here we present a spectroscopic comparative analysis of the Li doublet region of HD 123351, an active sub-giant star of solar metallicity. We fit the Li profile in three observed spectra characterized by different qualities: two very-high resolution spectra (Gecko@CFHT, R=120 000, SNR=400 and PEPSI@LBT, R=150 000, SNR=663) and a high-resolution SOPHIE@OHP spectrum (R=40 000, SNR=300). We adopt a set of model atmospheres, both 3D and 1D, having different stellar parameters (T_{eff} and log g). The 3D models are taken from the CIFIST grid of COBOLD model atmospheres and departures from LTE are considered for the lithium components. For the blends other than the lithium in this wavelength region we adopt the linelist of Melendez et al. (2012, A&A, 543, 29). We find consistent results for all three observations and an overall good fit with the selected list of atomic and molecular lines, indicating a high 6Li content.

The presence of 6Li is not expected in cool stellar atmospheres. Its detection is of crucial importance for understanding mixing processes in stars and external lithium production mechanisms, possibly related to stellar activity or planetray accretion of 6Li-rich material.

Comparison of observed spectra of the Li doublet region of HD 123351 around 670.8 nm. The Gecko (blue dotted line), SOPHIE (red dashed line) and PEPSI (green dashed-dotted line) spectra are superimposed on the Solar flux atlas by Kurucz (2005) (black continuous line) for a comparison. The locations of the Li I components and the dominant blends attributed to Fe  and CN are also indicated.


Read more:  Mott, Steffen, Caffau, & Strassmeier 2017, MemSAI 88, 68