To understand the origin of the abundance peculiarities of non-magnetic A-type stars, we present the first detailed chemical abundance analysis of a metallic line star HD 23193 (A2m) and an A-type subgiant HD 170920 (A5) which could have been a HgMn star on the main sequence. Our analysis is based on medium (R∼14 000) and high (R∼40 000) resolution spectroscopic data of the stars. The abundance of 18 elements are derived: C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Zn, Sr, Y, and Ba. The masses of HD 23193 and HD 170920 are estimated from evolutionary tracks, as 2.3±0.1 M and 2.9±0.1 M . The ages are found 635±33 Myr for HD 23193 and 480±50 Myr for HD 170920 using isochrones. The abundance pattern of HD 23193 shows deviations from solar values in the iron-peak elements and indicates remarkable overabundances of Sr (1.16), Y (1.03), and Ba (1.24) with respect to the solar abundances. We compare the derived abundances of this moderately rotating (vsini = 37.5 km s −1 ) Am star to the theoretical chemical evolution models including rotational mixing. The theoretically predicted abundances resemble our derived abundance pattern, except for a few elements (Si and Cr). For HD 170920, we find nearly solar abundances, except for C (−0.43), S (0.16), Ti (0.15), Ni (0.16), Zn (0.41), Y (0.57), and Ba (0.97). Its low rotational velocity (vsini = 14.5 km s −1 ), reduced carbon abundance, and enhanced heavy element abundances suggest that the star is most-likely an evolved HgMn star.

We determined the preliminary atmospheric parameters of the two A type stars HD 154713 and HD 137928. These stars’ high resolution echelle spectra, covering a wavelength range of 3800-7900 A, were obtained from the Coude Echelle Spectrograph attached to the 1.5 m telescope at the TÜBITAK National Observatory on the 24 th of April 2018. We derived the fundamental parameters by making use of photometric calibrations and profiles of hydrogen Balmer lines in our observed spectra. We estimated the metallicity ([Fe/H]) of HD 154713 as 0.41 and HD 137928 0.29. The metallicity value of HD 154713 may indicate it to be an Am star candidate.

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The abundance and detailed chemical analysis of HD 196821 are discussed, based on medium-and high-resolution spectra. The nature of this star is controversial: it has been classified variously as 𝜆 Bootis, Ap of the Si-Cr group, and HgMn. The atmospheric parameters are determined from the H β profile line from the medium-resolution spectra. We measure the chemical abundances of 19 atomic species from the high-resolution spectrum. The atmosphere of this star has slightly lower abundances of the light elements oxygen and magnesium with respect to solar values. Nevertheless, phosphorus, scandium, and chromium, as well as the heavy elements Sr, Y, Ba, and Yb, are enhanced compared to the solar values. The abundances of silicon, titanium, iron, and nickel are close to solar. HD 196821 shows an obvious overabundance of Mn II (2.11 dex) and Hg II (5.32 dex). Such a pattern is characteristic of chemically peculiar stars, particularly mercury-manganese stars. We also investigate the possible photometric variability of the star. The transiting exoplanet survey satellite light curve of HD 196821 reveals a rotational period of 5.7182 days and a harmonic of 2.8286 days, indicating the presence of high-contrast star-spots on its surface.

The atmospheric parameters and chemical abundances of two neglected Atype stars, 28 Peg and HD 202240, were derived using high resolution spectra obtained at the TÜBİTAK National Observatory. We determined the photo-