A scenario for the origin of the system PSR B 1757 - 24/supernova remnant ( SNR ) G 5.4 - 1.2 is proposed .
It is suggested that both objects are the remnants of a supernova ( SN ) that exploded within a pre-existing bubble blown-up by a runaway massive star ( the SN progenitor ) during the final ( Wolf-Rayet ) phase of its evolution .
This suggestion implies that ( a ) the SN blast centre was significantly offset from the geometric centre of the wind-blown bubble ( i.e .
from the centre of the future SNR ) , ( b ) the bubble was surrounded by a massive wind-driven shell , and ( c ) the SN blast wave was drastically decelerated by the interaction with the shell .
Therefore , one can understand how the relatively young and low-velocity pulsar PSR B 1757 - 24 was able to escape from the associated SNR G 5.4 - 1.2 and why the inferred vector of pulsar transverse velocity does not point away from the geometric centre of the SNR .
A possible origin of the radio source G 5.27 - 0.9 ( located between PSR B 1757 - 24 and the SNR G 5.4 - 1.2 ) is proposed .
It is suggested that G 5.27 - 0.9 is a lobe of a low Mach number ( \simeq 1.7 ) jet of gas outflowing from the interior of G 5.4 - 1.2 through the hole bored in the SNR ’ s shell by the escaping pulsar .
It is also suggested that the non-thermal emission of the comet-shaped pulsar wind nebula originates in the vicinity of the termination shock and in the cylindric region of subsonically moving shocked pulsar wind .
The role of magnetized wind-driven shells ( swept-up during the Wolf-Rayet phase from the ambient interstellar medium with the regular magnetic field ) in formation of elongated axisymmetric SNRs is discussed .