The abundances of heavy elements in BL138 – red giant of local group fornax dwarf spheroidal galaxy

Using the spectrum obtained with FLAMES/GIRAFFE multi-object spectrograph installed at ESO Very Large Telescope we investigated the absorption lines of heavy elements in the spectrum of BL138. This red giant star belongs to one of the Local Group members – Fornax dwarf spheroidal galaxy. The abundances of 12 stable chemical elements, namely Y, Zr, Nb, Mo, Ru, La, Ce, Pr, Nd, Eu, Dy, Er, Lu, and Hf. The abundance of radioactive elements Ac and Th are also investigated. The analysis of these abundances and also previously published investigation of BL138 allowed claiming that the distribution of abundances is different from that in the solar photosphere. The signs of r-process in the abundance pattern of BL138 are not important. The production of elements from barium to hafnium can be explained by s-process. The abundances of elements from yttrium to ruthenium are lower than it can be expected in the case of s-process synthesis. That is why it can be expected that several nuclear processes took place in the synthesis of these elements. The possibility of detection the actinium absorption line in the spectrum of BL138 clearly indicate the possibility of physical process which results in continuous production of actinium in the atmosphere of BL138. The actinium abundance can be close to logN(Ac)=1.9. It can be the result of hydrogen accretion from interstellar medium on stellar photosphere. The trends of abundances with second ionization potentials of corresponding chemical elements, and also by the emissions in the profiles of hydrogen H α line confirm this identification.