GBT22A-269

Probing the C+/C interface in the Orion Bar

Abstract

Emission from photodissociation regions (PDRs) dominates the non-stellar IR and submm spectrum of star-forming galaxies, and it is in PDRs that the coupling between UV photons and neutral gas takes place. Thus, PDRs are used to model a wide variety of galactic and extragalactic environments. However, high angular resolution observations of the prototypical strongly-irradiated PDR, the Orion Bar, pose challenges to standard PDR models. In particular, the separation of the C+/C interface and the dissociation front is smaller than predicted. We propose to observe carbon radio recombination lines at high-angular resolution (8" and 4.5") using the VLA and the GBT to measure separation between the C+/C interface and the dissociation front, while simultaneously determining the gas density and temperature. These independent constraints on the PDR structure and properties are fundamental to understand PDRs, and to inform the development of the next generation of PDR models.

Investigators

Name	Institution
Pedro Salas *	Green Bank Observatory
Alexander Tielens	Leiden, University of
Javier Goicoechea	Paris, Observatoire de
Sara Cuadrado	Consejo Superior de Investigaciones Científicas
Dave Frayer	Green Bank Observatory
Larry Morgan	Green Bank Observatory

* indicates the PI