We present an evolutionary sequence of models of the photoionized disk-wind outflow around forming massive stars based on the Core Accretion model .
The outflow is expected to be the first structure to be ionized by the protostar and can confine the expansion of the H ii region , especially in lateral directions in the plane of the accretion disk .
The ionizing luminosity increases as Kelvin-Helmholz contraction proceeds , and the H ii region is formed when the stellar mass reaches \sim 10 \ > – \ > 20 M _ { \odot } depending on the initial cloud core properties .
Although some part of outer disk surface remains neutral due to shielding by the inner disk and the disk wind , almost the whole of the outflow is ionized in 10 ^ { 3 } – 10 ^ { 4 } { yr } after initial H ii region formation .
Having calculated the extent and temperature structure of the H ii region within the immediate protostellar environment , we then make predictions for the strength of its free-free continuum and recombination line emission .
The free-free radio emission from the ionized outflow has a flux density of \sim ( 20 \ > – \ > 200 ) \times ( \nu / 10 { GHz } ) ^ { p } \ > { mJy } for a source at a distance of 1 kpc with a spectral index p \simeq 0.4 \ > – \ > 0.7 , and the apparent size is typically \sim 500 AU at 10 GHz .
The H 40 \alpha line profile has a width of about 100 \ > { \ > km\ > s ^ { -1 } } .
These properties of our model are consistent with observed radio winds and jets around forming massive protostars .