A parsec-size bow shock around Betelgeuse

We present new high-resolution IRAS (HiRes) images at 60 and 100 mu m of a bow shock or shell with a mean radius of 6' surrounding Betelgeuse (ct Orionis). The outermost section of this structure is at similar to 7' which corresponds to a physical scale of 0.8 pc at a distance of 400 pc. The images were made by applying a relative Burg entropy maximization algorithm to suppress the ringing around bright sources and allow the detection of nearby low surface brightness features. The shell is relatively narrow at 60 mu m (at the 1' HiRes resolution), asymmetric and oriented along the star's direction of motion. We propose that the shell is confined by the ram pressure of the interstellar medium. Using a shell flux of 110 Jy (at 60 mu m) within a radius of 7:5 we estimate mass of 0.14M(.) for the shell. (C) 1997 American Astronomical Society.