  A number of works infer radial temperature profiles of envelopes surrounding
young stellar objects using several rotational transitions in a pixel-by-pixel
or azimuthally-averaged basis. However, in many cases the assumption that the
rotational temperature is constant along the line of sight is made, while this
is not the case when a partially resolved envelope, assumed to be spherically
symmetric, is used to obtain values of temperature for different projected
radii. This kind of analysis (homogeneous analysis) is intrinsically
inconsistent. By using a spherical envelope model to interpret NH3 (1, 1) and
(2, 2) observations, we tested how robust it is to infer radial temperature
profiles of an envelope. The temperature and density of the model envelope are
power laws of radius, but the density can be flat for an inner central part.
The homogeneous analysis was applied to obtain radial temperature profiles, and
resulted that for small projected radii, where the optical depth of the lines
is high, the homogeneous temperature can be much higher than the actual
envelope temperature. In general, for larger projected radii, both the
temperature and the temperature power-law index can be underestimated by as
much as 40%, and 0.15, respectively. We applied this study to the infrared dark
cloud G14.225-0.506 for which the radial temperature profile was previously
derived from the dust emission at submillimeter wavelengths and the spectral
energy distribution. As expected, the homogeneous analysis underestimated both
the temperature and the temperature power-law index.
