Leibniz-Institut für Astrophysik Potsdam (AIP),
An der Sternwarte 16,
e-mail: firstname.lastname@example.org; email@example.com; firstname.lastname@example.org
Received: 16 October 2014
Accepted: 12 January 2015
Context. Although the relationship between lithium abundance in stars and their magnetic activity is commonly accepted, it is still unclear how the different phenomena related to it can increase the amount of Li, reduce its depletion, or be a source of bias for the measurements.
Aims. We study the rotational modulation of chromospheric and photospheric parameters of the young, active, single K2 dwarf LQ Hya and their connection with the variability of the Li i 6708 Å line.
Methods. A total of 199 high-resolution STELLA spectra and quasi-simultaneous photometry were used to compute effective temperature, gravity, and chromospheric activity indicators such as Hα and Hβ emission, Balmer decrement, and chromospheric electron density, as a function of the rotational phase. The variation of the Li i 6708 Å line was characterized in terms of equivalent width, abundance, and of 6Li/7Li isotopic ratio in the form of line shifts.
Results. Photospheric and chromospheric parameters show clear rotational modulation. Effective temperatures and continuum variations reveal a higher concentration of cool spots on the side of the star on which we also detect stronger chromospheric activity. Increased electron densities and the modulation of the He i D3 line suggest that the source of this activity can be a combination of plages and repeated low-intensity flares. The Li line and other temperature-sensitive lines are clearly enhanced by the spots located on the most active side of the star. Li abundances calculated taking into account the temperature variations simultaneously show, although with high dispersion, a small overabundance of this element that correlates well with the surface magnetic activity. In addition, the Li line center is more intensely redshifted than in the other hemisphere, which might be interpreted as a weak enrichment of 6Li.
Key words: stars: abundances / stars: activity / stars: chromospheres / stars: flare / stars: rotation / stars: individual: LQ Hydrae
Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC, and the Vienna-Potsdam Automatic Photoelectric Telescopes at Fairborn Observatory in Arizona, operated by AIP.
The numerical results of the spectral analysis are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/575/A57
© ESO, 2015