Detection of interstellar oxidaniumyl : Abundant H2O+ towards the star-forming regions DR21, Sgr B2, and NGC6334

  title={Detection of interstellar oxidaniumyl : Abundant H2O+ towards the star-forming regions DR21, Sgr B2, and NGC6334},
  author={V. Ossenkopf and Holger S. P. Muller and Dariusz C. Lis and Peter Schilke and Tom A. Bell and Simon Bruderer and Edwin Anthony Bergin and Cecilia Ceccarelli and Claudia Comito and J{\"u}rgen Stutzki and A. Bacman and Alain Baudry and A. O. Benz and Milena Benedettini and O. Bern{\'e} and Geoffrey A. Blake and A. C. Adwin Boogert and Sandrine Bottinelli and Francois Boulanger and Sylvie Cabrit and Paola Caselli and Emmanuel Caux and Jos{\'e} Cernicharo and Claudio Codella and Audrey Coutens and Nicolas Crimier and Nathan R. Crockett and Fabien Daniel and Karine Demyk and Pieter Dieleman and Carsten Dominik and M. L. Dubernet and Martin Emprechtinger and Pierre J. Encrenaz and Edith Falgarone and Kevin France and Asunci{\'o}n Fuente and Maryvonne Gerin and Thomas F. Giesen and Anna Maria Di Giorgio and Javier R. Goicoechea and Paul. F. Goldsmith and Rolf Gusten and Andrew I. Harris and Frank P. Helmich and Eric Herbst and Pierre Hily-Blant and Karl Jacobs and Thierry Jacq and Christine Joblin and Doug Johnstone and Claudine Kahane and Mihkel Kama and Thomas Klein and Alain Klotz and Carsten Kramer and William D. Langer and Bertrand Lefloch and Christian Leinz and A. Lorenzani and Steven D. Lord and S{\'e}bastien Maret and P. G. Martin and Jes{\'u}s Mart{\'i}n-Pintado and Carolyn McCoey and Martin Melchior and Gary J. Melnick and Karl M. Menten and Bhaswati Mookerjea and Patrick W. Morris and J. Anthony Murphy and David A. Neufeld and Brunella Nisini and S. Pacheco and Laurent Pagani and B{\'e}reng{\`e}re Parise and John C. Pearson and M. P'erault and Thomas G. Phillips and Rene Plume and Sally Quin and Ricardo Rizzo and Markus Rollig and Morvan C. Salez and Paolo Saraceno and Stephan Schlemmer and Robert Simon and Karl F. Schuster and Floris van der Tak and A. Tielens and David Teyssier and Neil A. Trappe and Charlotte Vastel and Serena Viti and Valentine Wakelam and Adam D. Walters and S P Wang and Nicholas D. Whyborn and Matthijs van der Wiel and Harold W. Yorke and S. Yu and Jonas Zmuidzinas},
  journal={Astronomy and Astrophysics},
Aims: We identify a prominent absorption feature at 1115 GHz, detected in first HIFI spectra towards high-mass star-forming regions, and interpret its astrophysical origin. Methods: The characteristic hyperfine pattern of the H2O+ ground-state rotational transition, and the lack of other known low-energy transitions in this frequency range, identifies the feature as H2O+ absorption against the dust continuum background and allows us to derive the velocity profile of the absorbing gas. By… 

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