Abundances in 4 Lacertae and $\nu$ Cephei

Abstract

Using Kurucz's ATLAS9 model atmospheres I performed LTE fine analyses of the supergiants 4 Lac and $\nu$ Cep. The spectra were obtained at 1.22-m telescope of the Dominion Astrophysical Observatory (DAO) by Saul J. Adelman. The atmospheric parameters were derived using the wings of ${\rm H}\beta$ and ${\rm H}\gamma$ profiles for each star, and from Fe I/II, Fe II/III, and Si II/III equilibria for 4 Lac, and from Fe I/II and Cr I/II equilibria for $\nu$ Cep. A microturbulence of $2.7\,{\rm km\,s}^{-1}$ for 4 Lac was found from Fe II lines while a mean value of $5.2\,{\rm km\,s}^{-1}$ for $\nu$ Cep from Cr II, Ti II and Fe II lines. The rotational and macroturbulent velocities are, respectively, $14\pm2{\rm km\,s}^{-1}$ and $15\pm 2\,{\rm km\,s}^{-1}$ for 4 Lac, and $26 \pm 2{\rm km\,s}^{-1}$ and $12 \pm 2{\rm km\,s}^{-1}$ for $\nu$ Cep. Their He, CNO and light element abundances are solar or overabundant while their iron peak and heavy element abundances are solar or underabundant. The derived results show that 4 Lac has nuclearly processed matter in its photosphere while $\nu$ Cep does not.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html