Spectral Energy Distributions of High Mass Proto Stellar Objects - Evidence for High Accretion Rates

Abstract

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.