Detailed photospheric abundances of 28 Peg and HD 202240

Abstract

The atmospheric parameters and chemical abundances of two neglected A-type stars, 28 Peg and HD 202240, were derived using high resolution spectra obtained at the TUBITAK National Observatory. We determined the photospheric abundances of eleven elements for 28 Peg and twenty for HD 202240, using equivalent-width measurement and spectral synthesis methods. Their abundance patterns are in good agreement with those of chemically normal A-type stars having similar atmospheric parameters. We pinpoint the position of these stars on the H-R diagram and estimate their masses and ages as; $2.60\pm0.10\ M_\odot$ and $650\pm50\ Myr$ for 28 Peg and $4.50\pm0.09\ M_\odot$ and $150\pm10\ Myr$ for HD 202240. To compare our abundance determinations with those of stars having similar ages and atmospheric parameters, we select members of open clusters. We notice that our target stars exhibit similar abundance patterns with these members.