Plane quasi-static thermoelastic problems are studied for domains of a
rbitrary shape with a slit. Special attention is paid to the case of p
oint heat sources. Three types of boundary conditions are considered o
n the sides of the slit: ideal contact, zero temperature, and heat iso
lation. For each of them the leading terms of the asymptotics of tensi
le and shear stress-intensity factors as t --> 0 are obtained. We show
, in particular, that a point heat source placed near one of the ends
of a finite rectilinear crack, while inducing compressive stresses nea
r this end, can cause dangerous tensile stresses in a neighborhood of
the other end.