Possible presence of magnetic fields and iron content of atmospheres of “Metallic” Am-stars

Abstract

Measurements with a CCD camera were made of two Fell lines at λ=6747.7 Å and 6149.2 Å in the spectra of 12 Am stars. The greater line strength of Fell λ 6147.7 Å relative to that of λ 6149.2 Å can be taken as evidence of a magnetic field in the atmosphere of the classical Am-star 15 Vul. Our observations support the conclusion of Mathys and Lanz [1] that a magnetic field is present in the atmosphere of yet another Am star, o Peg. For the rest of the stars studied the differences in the equivalent widths of the Fell lines can be explained by blending of the Fell line λ 6147.7 Å. Using the Fell line λ 6149.2 Å, which is free of blending, we estimate the iron content of the atmospheres of 12 Am stars with effective temperatures ranging from 7400 K to 9800 K. Our results indicate a star-to-star variation in log ε (Fe) of no less than 0.5 dex, a value greater than the measurement accuracy.