Volume 518, July-August 2010
Herschel: the first science highlights
|Number of page(s)||6|
|Published online||16 July 2010|
Letter to the Editor
A study of the distant activity of comet C/2006 W3 (Christensen) with Herschel and ground-based radio telescopes *,**
LESIA, Observatoire de Paris, 5 place Jules Janssen, 92195 Meudon, France e-mail: firstname.lastname@example.org
2 Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany
3 Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Belgium
4 Rutherford Appleton Laboratory, Oxfordshire, UK
5 California Institute of Technology, Pasadena, USA
6 F.R.S.-FNRS, Institut d'Astrophysique et de Géophysique, Liège, Belgium
7 European Space Astronomy Centre, Madrid, Spain
8 Instituto de Astrofísica de Andalucía (CSIC), Granada, Spain
9 Space Research Centre, Polish Academy of Science, Warszawa, Poland
10 Deutsches Zentrum für Luft- und Raumfahrt (DLR), Bonn, Germany
11 Blue Sky Spectroscopy Inc., Lethbridge, Alberta, Canada
12 Herschel Science Centre, ESAC, Madrid, Spain
13 University of Michigan, Ann Arbor, USA
14 CAB. INTA-CSIC Crta Torrejon a Ajalvir km 4. 28850 Torrejon de Ardoz, Madrid, Spain
15 LERMA, Observatoire de Paris, and Univ. Pierre et Marie Curie, Paris, France
16 SRON Netherlands Institute for Space Research, PO Box 800, Groningen, The Netherlands
17 Leiden Observatory, University of Leiden, The Netherlands
18 Joint ALMA Observatory, Santiago, Chile
19 University of Lethbridge, Canada
20 University of Cologne, Germany
21 University of Bern, Switzerland
Accepted: 7 May 2010
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-μm and 160-μm 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 μm 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.
Key words: comets: individual: C/2006 W3 (Christensen) / techniques: photometric / radio lines: planetary systems / radio continuum: planetary systems / comets: general
Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
Figures 2, 5, 6 are only available in electronic form at http://www.aanda.org
© ESO, 2010
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