Stellar mergers produce ``explosive outflows" that serve as transient sources of infrared line luminosity and inject mechanical energy early into the natal molecular cloud. -1 resolution maps of the, 63 and 145, ̆pmum fine-structure line emission from the wide-angle outflow in Orion BN/KL, the nearest explosive outflow. The data were obtained with SOFIA and include new, sensitive, 158, ̆pmum and OH line maps. They allowed us to disentangle the quiescent cloud gas, traced by a narrow component with a full width at half maximum (FWHM) of, from the outflow, traced by a broader ≃, 4, km, s-1 component with a line FWHM of about ; the latter exhibits a spatial distribution similar to that of the shock-excited H₂ emission seen with JWST. The ≃, 20--30, km, s^-1, 63, ̆pmum line displays a full width at zero intensity (FWZI) of ∼85, km, s -1 and shows foreground narrow absorptions against strong continuum sources. The OH, 119, ̆pmum line shows a prominent P-Cygni profile covering ∼160, km, s -1, similar to the FWZI of the CO lines. The total line luminosity is remarkably high, 86. 5, and a mass. The and intensity ratios reach very high values in the line wings (20–30 and 40–60, respectively), exceeding those found in photodissociation regions. These ratios are consistent with the presence of dense (n_̊m H, ≃, 105 to 10⁶, cm^-3) and warm (T, łesssim, 500, K), 63 and 145, ̆pmum of which 55, rate of is emitted in the broad component. This luminosity is comparable to the H₂ and CO line luminosities, implying an outflow mass-loss dot M ≃ (9. 1± 2. 6), 10^ -3 -1 M, ≃, (3. 3--5. 9), , 63, /, 145, 158 post-shock gas. We analyzed the fine-structure line-wing intensities using magnetized shock models that include UV irradiation, to which the line intensity is particularly sensitive. We find that the 158, ̆pmum and intensities are consistent with emission from dissociative shocks with velocities of and preshock gas densities of a few 10⁴, cm^ J-type -1 -3, illuminated by external UV radiation generated by surrounding fast shocks and possibly by massive (proto) stars in the region. We also report a broad, 63, ̆pmum emission feature around the BN star, which we attribute to an unresolved outflow or wind bow shock.
Goicoechea et al. (Wed,) studied this question.