A study of the distant activity of comet C/2006 W3 (Christensen) with Herschel and ground-based radio telescopes
Dominique Bockelée-Morvan
(1)
,
Paul Hartogh
(2)
,
Jacques Crovisier
(1)
,
Bart Vandenbussche
(3)
,
Bruce Swinyard
(4)
,
Nicolas Biver
(1)
,
Darek C. Lis
(5)
,
Christopher Jarchow
(2)
,
Raphaël Moreno
(1)
,
Damien Hutsemekers
(6)
,
Emmanuel Jehin
(6)
,
Michael Küppers
(7)
,
Luisa M. Lara
(8)
,
Emmanuel Lellouch
(1)
,
Jean Manfroid
(6)
,
Miguel de Val-Borro
(2)
,
Slawomira Szutowicz
(9)
,
M. Banaszkiewicz
(9)
,
Frank Bensch
(10)
,
M. I. Blecka
(9)
,
Martin Emprechtinger
(5)
,
Thérèse Encrenaz
(1)
,
Trevor Fulton
(11)
,
Mark R. Kidger
(12)
,
Miriam Rengel
(2)
,
Christoffel Waelkens
(3)
,
Edwin A. Bergin
(13)
,
Geoffrey A. Blake
(5)
,
J. A. D. L. Blommaert
(3)
,
José Cernicharo
(14)
,
Leen Decin
(3)
,
Pierre J. Encrenaz
(15, 16, 17)
,
Thijs de Graauw
(18)
,
Sarah J. Leeks
(4)
,
Alexander S. Medvedev
(2)
,
David A. Naylor
(19)
,
Rudolph Schieder
(20)
,
Nicholas Thomas
(21)
1
LESIA -
Laboratoire d'études spatiales et d'instrumentation en astrophysique
2 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
3 Instituut voor Sterrenkunde, Katholieke Universiteit Leuven
4 Rutherford Appleton Laboratory
5 Cahill Center for Astronomy and Astrophysics
6 Institut d'Astrophysique, Géophysique et Océanographie, Université de Liège
7 ESAC - European Space Astronomy Centre
8 IAA - Instituto de Astrofísica de Andalucía
9 Space Research Centre, Polish Academy of Sciences (Wroclaw)
10 DLR - Deutsches Zentrum für Luft- und Raumfahrt
11 BSS - Blue Sky Spectroscopy
12 Herschel Science Center, ESAC/ESA
13 Astronomy Department, University of Michigan
14 CAB - Centro de Astrobiología, Consejo Superior de Investigaciones Científicas (CSIC)/Instituto Nacional de Técnica Aeroespacial (INTA)
15 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
16 Instrumentation et télédétection
17 Dynamique des milieux interstellaires et plasmas stellaires
18 SRON - SRON Netherlands Institute for Space Research
19 Department of Physics, University of Lethbridge
20 Universität zu Köln = University of Cologne
21 UNIBE - Universität Bern / University of Bern
2 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
3 Instituut voor Sterrenkunde, Katholieke Universiteit Leuven
4 Rutherford Appleton Laboratory
5 Cahill Center for Astronomy and Astrophysics
6 Institut d'Astrophysique, Géophysique et Océanographie, Université de Liège
7 ESAC - European Space Astronomy Centre
8 IAA - Instituto de Astrofísica de Andalucía
9 Space Research Centre, Polish Academy of Sciences (Wroclaw)
10 DLR - Deutsches Zentrum für Luft- und Raumfahrt
11 BSS - Blue Sky Spectroscopy
12 Herschel Science Center, ESAC/ESA
13 Astronomy Department, University of Michigan
14 CAB - Centro de Astrobiología, Consejo Superior de Investigaciones Científicas (CSIC)/Instituto Nacional de Técnica Aeroespacial (INTA)
15 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
16 Instrumentation et télédétection
17 Dynamique des milieux interstellaires et plasmas stellaires
18 SRON - SRON Netherlands Institute for Space Research
19 Department of Physics, University of Lethbridge
20 Universität zu Köln = University of Cologne
21 UNIBE - Universität Bern / University of Bern
Résumé
Comet C/2006 W3 (Christensen) was observed in November 2009 at 3.3 AU from the Sun with Herschel.The PACS instrument acquired images of the dust coma in 70-mum and 160-mum filters and spectra covering several H2O rotational lines. Spectra in the range 450-1550 GHz were acquired with SPIRE. The comet emission continuum from 70 to 672 mum was measured, but no lines were detected. The spectral energy distribution indicates thermal emission from large particles and provides a measure of the size distribution index and dust production rate. The upper limit to the water production rate is compared to the production rates of other species (CO, CH3OH, HCN, H2S, OH) measured with the IRAM 30-m and Nançay telescopes. The coma is found to be strongly enriched in species more volatile than water, in comparison to comets observed closer to the Sun. The CO to H2O production rate ratio exceeds 220%. The dust-to-gas production rate ratio is on the order of 1.