  We present analysis of both the resolved X-ray emission line profiles and the
broadband X-ray spectrum of the O2 If* star HD 93129A, measured with the
Chandra HETGS. This star is among the earliest and most massive stars in the
Galaxy, and provides a test of the embedded wind shock scenario in a very dense
and powerful wind. A major new result is that continuum absorption by the dense
wind is the primary cause of the hardness of the observed X-ray spectrum, while
intrinsically hard emission from colliding wind shocks contributes less than
10% of the X-ray flux. We find results consistent with the predictions of
numerical simulations of the line-driving instability, including line
broadening indicating an onset radius of X-ray emission of several tenths
Rstar. Helium-like forbidden-to-intercombination line ratios are consistent
with this onset radius, and inconsistent with being formed in a wind-collision
interface with the star's closest visual companion at a distance of ~100 AU.
The broadband X-ray spectrum is fit with a dominant emission temperature of
just kT = 0.6 keV along with significant wind absorption. The broadband wind
absorption and the line profiles provide two independent measurements of the
wind mass-loss rate: Mdot = 5.2_{-1.5}^{+1.8} \times 10^{-6} Msun/yr and Mdot =
6.8_{-2.2}^{+2.8} \times 10^{-6} Msun/yr, respectively. This is the first
consistent modeling of the X-ray line profile shapes and broadband X-ray
spectral energy distribution in a massive star, and represents a reduction of a
factor of 3 to 4 compared to the standard H-alpha mass-loss rate that assumes a
smooth wind.
