Water production in comet 81P/Wild 2 as determined by Herschel/HIFI
Miguel de Val-Borro
(1)
,
Paul Hartogh
(1)
,
Jacques Crovisier
(2)
,
Dominique Bockelée-Morvan
(2)
,
Nicolas Biver
(2)
,
Darek C. Lis
(3)
,
Raphaël Moreno
(2)
,
Christopher Jarchow
(1)
,
Miriam Rengel
(1)
,
Slawomira Szutowicz
(4)
,
M. Banaszkiewicz
(4)
,
Frank Bensch
(5)
,
M. I. Blecka
(4)
,
Martin Emprechtinger
(3)
,
Thérèse Encrenaz
(2)
,
Emmanuel Jehin
(6)
,
Michael Küppers
(7)
,
Luisa M. Lara
(8)
,
Emmanuel Lellouch
(2)
,
Bruce Swinyard
(9)
,
Bart Vandenbussche
(10)
,
Edwin A. Bergin
(11)
,
Geoffrey A. Blake
(3)
,
J. A. D. L. Blommaert
(10)
,
José Cernicharo
(12)
,
Leen Decin
(10)
,
Pierre J. Encrenaz
(13, 14, 15)
,
Thijs de Graauw
(16)
,
Damien Hutsemekers
(6)
,
Mark R. Kidger
(17)
,
Jean Manfroid
(6)
,
Alexander S. Medvedev
(1)
,
David A. Naylor
(18)
,
Rudolph Schieder
(19)
,
Daphne Stam
(20)
,
Nicholas Thomas
(21)
,
Christoffel Waelkens
(10)
,
Ryszard Szczerba
(22)
,
Paolo Saraceno
(23)
,
A. M. Di Giorgio
(23)
,
S. Philipp
(24)
,
Thomas Klein
(24)
,
Volker Ossenkopf
(19)
,
Peer Zaal
(20)
,
Russell Shipman
(20)
1
MPS -
Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
2 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
3 Cahill Center for Astronomy and Astrophysics
4 Space Research Centre, Polish Academy of Sciences (Wroclaw)
5 DLR - German Aerospace Centre
6 Institut d'Astrophysique, Géophysique et Océanographie, Université de Liège
7 Rosetta Science Operations Centre
8 IAA - Instituto de Astrofísica de Andalucía
9 STFC Rutherford Appleton Laboratory, Harwell Innovation Campus, Didcot
10 Instituut voor Sterrenkunde, Katholieke Universiteit Leuven
11 Astronomy Department, University of Michigan
12 LAM - Laboratorio de Astrofísica Molecular, CAB-CSIC/INTA
13 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
14 Instrumentation et télédétection
15 Dynamique des milieux interstellaires et plasmas stellaires
16 Joint ALMA Observatory, Santiago
17 Science Centre
18 Department of Physics and Astronomy, University of Lethbridge
19 Physikalisches Institut, Universität zu Köln
20 SRON - SRON Netherlands Institute for Space Research
21 Physikalisches Institut, Universität Bern
22 CAMK - Centrum Astronomiczne im. M. Kopernika, Torun
23 Istituto Fisica Spazio Interplanetario, INAF
24 MPIfR - Max-Planck-Institut für Radioastronomie
2 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
3 Cahill Center for Astronomy and Astrophysics
4 Space Research Centre, Polish Academy of Sciences (Wroclaw)
5 DLR - German Aerospace Centre
6 Institut d'Astrophysique, Géophysique et Océanographie, Université de Liège
7 Rosetta Science Operations Centre
8 IAA - Instituto de Astrofísica de Andalucía
9 STFC Rutherford Appleton Laboratory, Harwell Innovation Campus, Didcot
10 Instituut voor Sterrenkunde, Katholieke Universiteit Leuven
11 Astronomy Department, University of Michigan
12 LAM - Laboratorio de Astrofísica Molecular, CAB-CSIC/INTA
13 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
14 Instrumentation et télédétection
15 Dynamique des milieux interstellaires et plasmas stellaires
16 Joint ALMA Observatory, Santiago
17 Science Centre
18 Department of Physics and Astronomy, University of Lethbridge
19 Physikalisches Institut, Universität zu Köln
20 SRON - SRON Netherlands Institute for Space Research
21 Physikalisches Institut, Universität Bern
22 CAMK - Centrum Astronomiczne im. M. Kopernika, Torun
23 Istituto Fisica Spazio Interplanetario, INAF
24 MPIfR - Max-Planck-Institut für Radioastronomie
Résumé
The high spectral resolution and sensitivity of Herschel/HIFI allows for the detection of multiple rotational water lines and accurate determinations of water production rates in comets. In this Letter we present HIFI observations of the fundamental 110-101 (557 GHz) ortho and 111-00 (1113 GHz) para rotational transitions of water in comet 81P/Wild 2 acquired in February 2010. We mapped the extent of the water line emission with five point scans. Line profiles are computed using excitation models which include excitation by collisions with electrons and neutrals and solar infrared radiation. We derive a mean water production rate of 1.0 × 1028 molecules s-1 at a heliocentric distance of 1.61 AU about 20 days before perihelion, in agreement with production rates measured from the ground using observations of the 18-cm OH lines. Furthermore, we constrain the electron density profile and gas kinetic temperature, and estimate the coma expansion velocity by fitting the water line shapes.
Domaines
Astrophysique [astro-ph]
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