Anomalous abundance of lithium in the roAp star HD 12098 recently discovered in the northern hemisphere of the sky

Abstract

of Sciences) using the NES echelle spectrometer have revealed several stars with an anomalous lithium abundance. The oscillating star HD 12098, which is the first roAp star in the northern hemisphere of the sky, merits special attention. Strong, variable LiI 6708 Å line was observed in the spectrum of this star. There are not enough observations for a reliable analysis by Doppler mapping, but there are enough to indicate the presence of lithium spots on the surface of this star similar to the roAp stars HD 83368 and HD 60435, on whose surfaces spots with a high lithium abundance have been reliably detected. Parameters for a model of its atmosphere have been chosen using the method of synthetic spectra based on atmospheric models including lines from the VALD list and several additional blended REE lines calculated by the authors. The profile of the lithium LiI 6708 Å blend has been calculated taking the magnetic field into account using the SYNTHM code. A lithium abundance has been determined for two phases of the rotation of HD 12098 that is anomalously high compared to the solar and meteoritic abundances. The large difference in the lithium abundance in the two phases (in two different regions on the star's surface) exceeds 0.5 dex and is very close to that which we have found by analyzing the spectra of the roAp stars HD 83368 and HD 60435. Thus, we have discovered yet another roAp star, HD 12098, with lithium spots on its surface.

Abnormal lithium abundance in several Ap-Bp stars

“…The oscillating star HD 12098, first roAp star, opened recently on northern sky [3], was among these stars. The spectrum of this star showed strong and variable Li I line 6708 Å, analysis of which revealed a high abundance of lithium [1]. It has been shown the presence of lithium spots on the surface of the star [17], similar to two roAp stars HD 83368 and HD 60435, for which lithium spots were previously detected on their surface [15].…”

New results of the spectral observations of CP stars

“…In the spectrum of this star we detected a strong and variable Li I 6708Å, indicating that Li spots must exist on the surface of this star, which is the first roAp star discovered on the northern hemisphere. Quantitative analysis of this star is presented in Shavrina et al (2008).…”