THE BOW SHOCK STRUCTURE OF IRS-7 - WIND-WIND COLLISION NEAR THE GALACTIC-CENTER

High-resolution multiconfiguration VLA observations of IRS 7, a mass-losing supergiant near the Galactic center, reveal ionized gas with a bow shock structure at lambda = 2 cm. The apex of the bow shock is facing more toward the cluster of blue stellar objects, known as IRS 16, than Sgr A*, the compact nonthermal source near the dynamical center of the Galaxy. This implies that the shape of the mass-losing envelope of IRS 7 is influenced by Galactic winds from IRS 16. By comparing the morphology of the ionized envelope of IRS 7 with simple theoretical modeling of the bow shock structure, we conclude that the shape of the shock results from the collision between the Galactic center and stellar winds rather than from the motion of IRS 7 through the interstellar medium. In particular, we account for the observed flaring of the shock surface in terms of the Galactic wind originating from a region near the dynamical center of the Galaxy (the IRS 16 complex). In addition, our theoretical fits of the bow structure yield an independent positioning of IRS 7 itself, which is consistent with that due to near-IR astrometry.