First NH3 detection of the Orion Bar

B Larsson, R Liseau, P Bergman, P Bernath, J H Black, R S Booth, V Buat, C L Curry, P Encrenaz, E Falgarone, P Feldman, M Fich, H G Floren, U Frisk, M Gerin, E M Gregersen, J Harju, T Hasegawa, L E B Johansson, S KwokA Lecacheux, T Liljestrom, K Mattila, G F Mitchell, L H Nordh, M Olberg, G Olofsson, L Pagani, R Plume, I Ristorcelli, A Sandqvist, F von Scheele, N F H Tothill, K Volk, C D Wilson, A Hjalmarson

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Odin has successfully observed three regions in the OrionA cloud, i.e. OriKL, Ori S and the Orion Bar, in the 572.5 GHz rotational ground state line of ammonia, ortho-NH3 (J; K) = ( 1; 0) --> (0; 0), and the result for the Orion Bar represents the first detection in an ammonia line. Several velocity components are present in the data. Specifically, the observed line profile from the Orion Bar can be decomposed into two components, which are in agreement with observations in high-J CO lines by Wilson et al. (2001). Using the source model for the Orion Bar by these authors, our Odin observation implies a total ammonia abundance of NH3/H-2 = 5 X 10(-9).

Original languageEnglish
Pages (from-to)L69-L72
Number of pages4
JournalAstronomy & Astrophysics
Issue number3
Publication statusPublished - May 2003


  • ISM : individual objects : Orion A
  • clouds
  • molecules
  • abundances
  • stars : formation
  • KL

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