Evaluating Promethium Abundance in the Atmospheres of Magnetically Peculiar Star HD 25 354

This study examines the absorption lines of promethium, a radioactive element with a short half-life, in the spectra of the magnetic peculiar star HD 25 354, which belongs to the spectral class A0Vp. It also determines the promethium abundance in the star's atmosphere. The analysis utilized an archival spectrum of HD 25 354 from the ELODIE database, obtained in 1996, covering the wavelength range of 400.0-680.0 nm, with a spectral resolution of R = 42 000 and a signal-to-noise ratio (S/N) of 100, recorded at the 1.93-m telescope at the Haute-Provence Observatory. Additionally, spectra collected by F. Musaev in 2006, using the 2-m telescope at Terskol Peak Observatory, were analyzed. These spectra covered the wavelength range of 370.0-940.0 nm, with S/N = 200 and R = 60 000. The previously determined atmospheric parameters of the star (T-eff = 12 800 K, log g = 4.15, V-micro = 0.23 km/s) and the chemical composition of its elements were used to calculate a synthetic spectrum over a wide range. This synthetic spectrum generally gave a satisfactory approximation of the observed spectrum. By comparing the synthetic spectrum of HD 25 354 with the observed data, 11 lines of promethium were identified, and its abundance was determined. The promethium abundance was found to be consistent with the abundance levels of other lanthanides, with a value of log N = 5.8-5.9 on the hydrogen scale, where log N(H) = 12. According to literature data, the promethium abundance in the atmosphere of HR 465 (log N = 5.05) is also within the range of lanthanide abundance.