Absorption features from the Lyman and Werner bands of interstellar molecular hydrogen were recorded by the Interstellar Medium Absorption Profile Spectrograph ( IMAPS ) at \lambda / \Delta \lambda = 80 , 000 in the spectra of \delta Ori A and \epsilon Ori .
The objective was to find and study more examples of an unusual phenomenon found for one of the velocity components of H _ { 2 } in the spectrum of \zeta Ori by Jenkins & Peimbert ( 1997 ) .
Specifically , they detected a gradual shift in velocity and broadening for features arising from progressively higher rotational excitations J .
This effect appears to be absent in the spectra of both \delta and \epsilon Ori , which are only a few degrees away in the sky from \zeta Ori .
The absence of atomic material at a large negative velocity in the spectra of \delta and \epsilon Ori ( and its presence in \zeta Ori ) supports a proposal by Jenkins & Peimbert that the line of sight to \zeta intercepts a bow shock facing away from us , perhaps created by the collision of wind-like material with some foreground obstruction .
One edge of the molecular cloud complex Lynds 1630 is situated close to \zeta Ori in the sky , but we present some evidence that seems to indicate that the cloud is more distant , in which case it could not serve as the obstruction .
However it is possible that the outermost extension of a high-speed jet from a star forming within the cloud can explain the high-velocity material and the shock front created by it .

For both stars , the H _ { 2 } absorption features are separated into two velocity components .
Total H _ { 2 } column densities toward \delta and \epsilon Ori are 5.5 \times 10 ^ { 14 } and 1.9 \times 10 ^ { 16 } { cm } ^ { -2 } , respectively .
When these values are compared to the column densities of H I , the fractions of H atoms bound in molecular form 2 N ( { H } _ { 2 } ) / [ 2 N ( { H } _ { 2 } ) + N ( { H~ { } I } ) ] = 7 \times 10 ^ { -6 } for \delta and 1.3 \times 10 ^ { -4 } for \epsilon .
The rotation temperatures of the molecules with J > 2 toward \epsilon Ori indicate that the gas is in the general vicinity of the stars that emit UV fluxes capable of rotationally pumping the molecules .
For the strongest component of H _ { 2 } toward \delta Ori , the pumping rate is lower and consistent with a general UV flux level in the plane of the Galaxy .