Spectroscopic analysis of alpha andromedae

A detailed abundance analysis of the Hg–Mn star And is carried out with the method of fine analysis based on high-dispersion spectrograms obtained at the Haute Provence Observatory. In the derivation of effective temperature, we have considered the spectral energy distribution from far UV to the near IR, the line blanketing in the UV region and the reddening of And. The observed energy distribution, manganese ionization equilibrium and hydrogen-line profiles indicate that the atmosphere can be represented by a model withT _eff=13850350 K, logg=3.850.15 (in CGS) and with =3.00.5 km s^–1. Our analysis shows that the abundances of C and Si are normal; Mg, S, and Fe slightly overabundant; and P, Mn, Ga, Sr, Y, Zr, Eu, and Hg are considerably overabundant by 2.02, 2.68, 5.48, 1.13, 3.70, 3.35, 4.40, and 6.02 dex, respectively, relative to the solar values. A comparison of our abundances with those by others shows large discrepancies.A discussion of the atmospheric structure of And suggests that the star has a circumstellar envelope, and that there is some contribution to the observed spectrum from that envelope.On leave of absence from the Dept. of Astronomy, Faculty of Sciences, University of Ankara, Ankara, Turkey.