The Horsehead Nebula revealed by JWST
The Horsehead Nebula has been discovered in the visible range as a dark cloud appearing in extinction at the edge of a giant molecular complex in Orion. It is a photo-dominated region (PDR) illuminated by a massive star. It is of great interest to astrophysicists, as it is the ideal object for understanding the interactions between UV radiation emitted by stars and interstellar matter, the way radiation propagates inside dense clouds, and the impact of radiation on matter (photo-evaporation, ionization, dissociation, fragmentation, heating, etc.).
Infrared images from JWST's NIRCam and MIRI instruments reveal for the first time the small-scale structure of the illuminated edge of the Horsehead, where matter is being photo-evaporated, atoms are being ionized, molecules and in particular dihydrogen are being formed and dissociated, grains are fragmenting, ...
In addition to angular resolution and sensitivity, the JWST has unique imaging capabilities that have enabled images to be obtained in more than twenty different spectral bands, enabling a detailed analysis of gas and grain emission and extinction that has just been published in Abergel et al. 2024 (https://www.aanda.org/articles/aa/pdf/forth/aa49198-24.pdf). The work will continue with the analysis of spectroscopic data and modelling of the observations.
The observations of the Horsehead were obtained as part of the guaranteed time of the MIRI and NIRCam instruments. The IAS is a member of the European consortium for the MIRI mid-infrared instrument. The laboratory was involved in the optical testing of the MIRI imager, is responsible for the processing and dissemination of imager data within the French MIRI center of expertise, and has set up the INCLASS joint laboratory with the SME ACRI-ST for the fusion of imaging and spectroscopy data.
Press release : https://esawebb.org/news/weic2411/
People involved: Alain Abergel, Olga Kannavou, Emilie Habart, Meriem Elyajouri, Laurent Verstraete, Antony Jones, Dan Pineau, Nicolas Monnier, Pierre Dell’Ova, Loïc Maurin
