The chemical composition, gravity and temperature of Vega.

Several flux-constant, line-blanketed model stellar atmospheres have been computed for the bright star Vega. The stellar effective temperature has been found to be 9650 K by comparisions of observed and computed absolute fluxes at 5556 A and of relative absolute fluxes between 3300 and 10800 A. The Balmer line profiles give log g=3.9 +- 0.2, consistent with the result from the Balmer jump and with that found from the radius and (estimated) mass. Te Ti II and Fe II curves of growth give abundances of log N(Ti)=4.7 +- 0.3 and log N(Fe)=7.1 +- 0.3 on the scale log N(H)=12.0. These abundances are slightly less than normalized meteoritic values and solar values deduced from ionized lines. The local thermodynamic equilbrium (LTE) Fe I curve of growth gives log N(Fe)=6.9 +- 0.3, whereas correction for non-LTE effects suggests log N(Fe)=7.5 +- 0.3.