We show that the electron thermal conductivity may strongly affect the heliosheath plasma flow and the global pattern of the solar wind ( SW ) interaction with the local interstellar medium ( LISM ) .
In particular , it leads to strong reduction of the inner heliosheath thickness that makes possible to explain ( qualitatively ) why Voyager 1 ( V1 ) has crossed the heliopause at unexpectedly small heliocentric distance of 122 AU .
To estimate the effect of thermal conductivity we consider a limiting case when thermal conduction is very effective .
To do that we assume the plasma flow in the entire heliosphere is nearly isothermal .

Due to this effect , the heliospheric distance of the termination shock has increased by about 15 AU in V1 direction compared to the adiabatic case with \gamma = 5 / 3 .
The heliospheric distance of the heliopause has decreased by about 27 AU .
As a result , the thickness of the inner heliosheath in the model has decreased by about 42 AU and become equal to 32 AU .