We present Submillimeter Array observations , in the 1.3 mm continuum and the CH _ { 3 } CN ( 12 _ { K } –11 _ { K } ) line of 17 hot molecular cores associated with young high-mass stars .
The angular resolution of the observations ranges from 1 \farcs 0 to 4 \farcs 0 .
The continuum observations reveal large ( > 3500 AU ) dusty structures with gas masses from 7 to 375 M _ { \odot } , that probably surround multiple young stars .
The CH _ { 3 } CN line emission is detected toward all the molecular cores at least up to the K = 6 -component and is mostly associated with the emission peaks of the dusty objects .
We used the multiple K -components of the CH _ { 3 } CN and both the rotational diagram method and a simultaneous synthetic LTE model with the XCLASS program to estimate the temperatures and column densities of the cores .
For all sources , we obtained reasonable fits from XCLASS by using a model that combines two components : an extended and warm envelope , and a compact hot core of molecular gas , suggesting internal heating by recently formed massive stars .
The rotational temperatures lie in the range of 40-132 K and 122-485 K for the extended and compact components , respectively .
From the continuum and CH _ { 3 } CN results , we infer fractional abundances from 10 ^ { -9 } to 10 ^ { -7 } toward the compact inner components , that increase with the rotational temperature .
Our results agree with a chemical scenario in which the CH _ { 3 } CN molecule is efficiently formed in the gas phase above 100-300 K , and its abundance increases with temperature .