PDRs4All: A JWST Early Release Science Program on Radiative Feedback from Massive Stars

Abstract

Massive stars disrupt their natal molecular cloud material through radiative and mechanical feedback processes. These processes have profound effects on the evolution of interstellar matter in our Galaxy and throughout the universe, from the era of vigorous star formation at redshifts of 1–3 to the present day. The dominant feedback processes can be probed by observations of the Photo-Dissociation Regions (PDRs) where the far-ultraviolet photons of massive stars create warm regions of gas and dust in the neutral atomic and molecular gas. PDR emission provides a unique tool to study in detail the physical and chemical processes that are relevant for most of the mass in inter- and circumstellar media including diffuse clouds, proto-planetary disks, and molecular cloud surfaces, globules, planetary nebulae, and star-forming regions. PDR emission dominates the infrared (IR) spectra of star-forming galaxies. Most of the Galactic and extragalactic observations obtained with the James Webb Space Telescope (JWST) will therefore arise in PDR emission. In this paper we present an Early Release Science program using the MIRI, NIRSpec, and NIRCam instruments dedicated to the observations of an emblematic and nearby PDR: the Orion Bar. These early JWST observations will provide template data sets designed to identify key PDR characteristics in JWST observations. These data will serve to benchmark PDR models and extend them into the JWST era. We also present the Science-Enabling products that we will provide to the community. These template data sets and Science-Enabling products will guide the preparation of future proposals on star-forming regions in our Galaxy and beyond and will facilitate data analysis and interpretation of forthcoming JWST observations.

Electronic effects in the dissociative ionisation of pyrene clusters

“…This is particularly true in the case of dissociative ionisation upon VUV irradiation, as studied in this work, a key process for the evolution of PAH clusters in PDRs that may be revealed by the observations from the James Webb Space Observatory. 57…”

The James Webb Space Telescope Mission

“…These interactions create Photo-Dissociation Regions (PDRs), which dominate the infrared spectra of star-forming galaxies and drive the evolution of star formation from interstellar matter. PDRs4All (Berné et al 2022) consists of NIRCam and MIRI imaging, and MIRI MRS and NIRSpec IFU spectroscopy of PDRs in the Orion Bar.…”

Dust around Massive Stars Is Agnostic to Galactic Environment: New Insights from PHAT/BEAST

“…As such, 2.12 μm emission can be used to trace the surface density of molecular structures at subparsec scales. While studies of H 2 with JWST have so far mainly been located in the Milky Way (Berné et al 2022), PAHs have been used in extragalactic studies to show star formation occurring in smaller spurs located between spiral arms (e.g., Williams et al 2022).…”