2008/05/12 by A. Tappe, C. J. Lada, J. H. Black +2
Chemistry · Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Atomic physics #Chemistry #Emission spectrum #Excitation #Excited state #Herbig–Haro object #Infrared #Interstellar medium #Outflow #Photochemistry #Photodissociation #Physics #Rotational energy #Rotational temperature #Spectral line #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/589998
ApJ Letters, in press
arxiv created 2008/05/12 · openalex publication_date 2008/05/27 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a 5-37 μm infrared spectrum obtained with the Spitzer Space Telescope toward the southeastern lobe of the young protostellar outflow HH 211. The spectrum shows an extraordinary sequence of OH emission lines arising in highly excited rotational levels up to an energy E /k ≈ 28,200 K above the ground level. This is, to our knowledge, by far the highest rotational excitation of OH observed in the interstellar medium. The spectrum also contains several pure rotational transitions of H 2 O ( v = 0), H 2 ( v = 0) S (0)- S (7), HD ( v = 0) R (3)- R (6), and atomic fine-structure lines of [Fe II], [Si II], [Ne II], [S I], and [Cl I]. The origin of the highly excited OH emission is most likely the photodissociation of H 2 O by the UV radiation generated in the terminal outflow shock of HH 211.