We show that the UV spectrum ( 1280–3200 Å ) of the “ superficially normal ” A-star Vega , as observed by the IUE satellite at a resolution comparable to the star ’ s rotational broadening width , can be fit remarkably well by a single-temperature synthetic spectrum based on LTE atmosphere models and a newly constructed UV line list .
If Vega were a normal , equator-on , slow-rotating star , then its spectrum and our analysis would indicate a temperature of T _ { eff } \simeq 9550 K , surface gravity of \log g \simeq 3.7 , general surface metallicity of [ m/H ] \simeq - 0.5 , and a microturbulence velocity of v _ { turb } \simeq 2.0 km s ^ { -1 } .
Given its rapid rotation and nearly pole-on orientation , however , these parameters must be regarded as representing averages across the observed hemisphere .
Modeling the complex UV line spectrum has allowed us to determine the specific surface abundances for 17 different chemical elements , including CNO , the light metals , and the iron group elements .
The resultant abundance pattern agrees in general with previous results , although there is considerable scatter in the literature .
Despite its peculiarities , Vega has turned out to provide a powerful test of the extent of our abilities to model the atmospheric properties of the early A-stars , particularly the detailed UV line spectrum .
The value of the measurements from this pilot study will increase as this analysis is extended to more objects in the rich high-dispersion IUE data archive , including both normal and peculiar objects .