  We describe and analyze HST/STIS observations of the G2 V star alpha Centauri
A (alpha Cen A, HD 128620), a star similar to the Sun. The high resolution
echelle spectra obtained with the E140H and E230H gratings cover the complete
spectral range 1133-3150 Angstrom with a resolution of 2.6 km/s, an absolute
flux calibration accurate to +/-5%, and an absolute wavelength accuracy of
0.6-1.3 km/s. We present here a study of the E140H spectrum covering the
1140-1670 Angstrom spectral range, which includes 671 emission lines
representing 37 different ions and the molecules CO and H_2. For alpha Cen A
and the quiet and active Sun, we intercompare the redshifts, nonthermal line
widths, and parameters of two Gaussian representations of transition region
lines (e.g., Si IV, C IV), infer the electron density from the O IV intersystem
lines, and compare their differential emission measure distributions. One
purpose of this study is to compare the alpha Cen A and solar UV spectra to
determine how the atmosphere and heating processes in alpha Cen A differ from
the Sun as a result of the small differences in gravity, age, and chemical
composition of the two stars. A second purpose is to provide an excellent high
resolution UV spectrum of a solar-like star that can serve as a proxy for the
Sun observed as a point source when comparing other stars to the Sun.
