Contributed Talk - Splinter SOFIA

Tuesday, 12 September 2023, 16:15   (H 3006)

Velocity-resolved high-J CO emission from high-mass star-forming regions

Thanh Dat Hoang (1), Agata Karska (1,2), Min Young Lee (3), Friedrich Wyrowski (1), Ngoc Tram Le (1), Aiyuan Y. Yang (4), Karl Menten (1)
Max Planck Institute for Radio Astronomy (1), Nicolaus Copernicus University (2), Korea Astronomy and Space Science Institute (3), Chinese Academy of Sciences (4)

High-mass stars are powerhouses of galaxies, and their formation involves energetic processes such as jets/outflows that provide mechanical feedback and regulate the local interstellar medium. In this talk, we present observations of highly-excited CO lines toward 13 massive star-forming regions using high spectral resolution spectroscopy from SOFIA/GREAT. Most of our targets show a strong CO 11-10 and CO 16-15 emission, characterised by broad line wings associated with outflows. Line wings' contributions to velocity-integrated emission vary over a wide range from 28% to 76% but do not correlate with source evolutionary stages. Assuming local thermodynamics equilibrium (LTE), we determined excitation temperatures of 110-200 K for the full line profiles and 120-220 K for the line wings. Non-LTE RADEX modelling indicates gas densities of 1e5-1e7 cm-3, kinetic temperatures of 150-500K, and CO column densities of 1e17-1e18 cm2 in the line wings, comparable to the physical conditions of deeply embedded low-mass protostars. The correlation between velocity-integrated CO fluxes and bolometric luminosity spans 7 orders of magnitude, including low- and intermediate-mass protostars. Therefore, similar processes are likely responsible for the excitation of high-J CO lines over a wide range of physical scales.