  The spectral energy distributions (SEDs), spanning the mid-infrared to
millimeter wavelengths, of a sample of 13 high-mass protostellar objects
(HMPOs) were studied using a large archive of 2-D axisymmetric radiative
transfer models. Measurements from the Spitzer GLIMPSE and MIPSGAL surveys and
the MSX survey were used in addition to our own surveys at millimeter and
submillimeter wavelengths to construct the SEDs, which were then fit to the
archive of models. These models assumed that stars of all masses form via
accretion and allowed us to make estimates for the masses, luminosities and
envelope accretion rates for the HMPOs. The models fit the observed SEDs well.
The implied envelope accretion rates are high, $\approx 10^{-2.5} \msun/yr$,
consistent with the accretion-based scenario of massive star formation. With
the fitted accretion rates and with mass estimates of up to $\sim 20 \msun$ for
these objects, it appears plausible that stars with stellar masses $M_{\ast} >
20 \msun$ can form via accretion.

Astrophysics