FEEDBACK: a SOFIA Legacy Program to Study Stellar Feedback in Regions of Massive Star Formation

Abstract

FEEDBACK is a SOFIA (Stratospheric Observatory for Infrared Astronomy) legacy program dedicated to study the interaction of massive stars with their environment. It performs a survey of 11 galactic high mass star forming regions in the 158 µm (1.9 THz) line of [C II] and the 63 µm (4.7 THz) line of [O I]. We employ the 14 pixel Low Frequency Array (LFA) and 7 pixel High Frequency Array (HFA) upGREAT heterodyne instrument to spectrally resolve (0.24 MHz) these far-infrared fine structure lines. With a total observing time of 96h, we will cover ∼6700 arcmin 2 at 14.1 angular resolution for the [C II] line and 6.3 for the [O I] line. The observations started in spring 2019 (Cycle 7). Our aim is to understand the dynamics in regions dominated by different feedback processes from massive stars such as stellar winds, thermal expansion, and radiation pressure, and to quantify the mechanical energy injection and radiative heating efficiency. This is an important science topic because feedback of massive stars on their environment regulates the physical conditions and sets the emission characteristics in the interstellar medium (ISM), influences the star formation activity through molecular cloud dissolution and compression processes, and drives the evolution of the ISM in galaxies. The [C II] line provides the kinematics of the gas and is one of the dominant cooling lines of gas for low to moderate densities and UV fields. The [O I] line traces warm and highdensity gas, excited in photodissociations regions with a strong UV field or by shocks. The source sample spans a broad range in stellar characteristics from single OB stars, to small groups of O stars, to rich young stellar clusters, to ministarburst complexes. It contains wellknown targets such as Aquila, the Cygnus X region, M16, M17, NGC7538, NGC6334, Vela, and W43 as well as a selection of H II region bubbles, namely RCW49, RCW79, and RCW120. These [C II] maps, together with the less explored [O I] 63 µm line, provide an outstanding database for the community. They will be made publically available and will trigger further studies and follow-up observations.

[CII] $158\,μ\mathrm{m}$ line emission from Orion A. I. A template for extragalactic studies?

“…Here we try to answer these questions with square-degree [C ii] 158 µm mapping observations of the prototypical star-forming cloud in the disk of the Milky Way, Orion A (Pabst et al 2019). Our study is relevant in the extragalactic context because, thanks to Herschel and now much more efficiently with SOFIA, we have access to velocity-resolved wide-field (spatial scales of several parsec) maps of the [C ii] 158 µm emission over nearby, spatially-resolved regions of massive star formation (Goicoechea et al 2015b;Pabst et al 2019Pabst et al , 2020Schneider et al 2020). This means that any variation of the surface brightness spatial distribution of these observables can be directly linked to the characteristics of each line-of-sight, its local physical and FUV-illumination conditions, and its SFR surface density.…”