  In this work, we choose a minimal coupling interaction between massive Klein
Gordon (KG) quantum scalar free fields and Janis-Newman-Winicour (JNW)
spherically symmetric static black hole, to produce its Hawking temperature and
luminosity. This is done by calculating asymptotic wave solutions at near and
far from the black hole horizon. They are orthogonal mode solutions of local
Hilbert spaces. By using these mode solutions, we calculated Bogolubov
coefficients and then, we investigated number density matrix of created
particles. Mathematical calculations show that this is not exactly similar to
the Planck`s black body radiation energy density distribution but, it is "gray"
body radiation distribution depended to the emitted Hawking particles
frequency. Their difference is a non-vanishing absorptivity factor of
backscattered particles after to form horizon of a collapsing body. Our
motivation is determination of position of Hawking created pairs in which, two
different proposals are proposed, so called as "fairwall" and "quantum
atmosphere".
