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Photometric observations of comet 81P/Wild 2 during the 2010 perihelion passage

Ho, T.-M. and Bertinie, I. and Barbieri, C. and Lazzarin, M. and Cremonese, G. and Küppers, M. and Magrin, S. and Marchi, S. (2012) Photometric observations of comet 81P/Wild 2 during the 2010 perihelion passage. Astronomy & Astrophysics, 541. EDP Sciences. doi: 10.1051/0004-6361/201118004. ISSN 0004-6361.

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Context. The Jupiter-family comet 81P/Wild 2, target of the NASA Stardust mission, is very important in the context of the studies of pristine objects in the solar system. First, it was only recently deflected into the present orbit, having spent at least 300 yr at higher heliocentric distance prior to the orbital change in 1974. It is therefore likely that the comet experienced a recent activation with consequent low alteration of its original material. Second, it is the only comet whose coma material was brought back to Earth for laboratory analysis. We observed the object between 2010 February 9 and September 9 for a total of 11 nights during the 2010 perihelion passage. Aims. The goals of the campaign were the characterization of the comet’s dust activity and the comparison with previous apparitions to derive hints on the secular behavior of the object. Methods. Broadband R- and I-images were acquired using three instruments: ALFOSC, CAMELOT, and TCP. The first one is mounted at the Nordic Optical Telescope on La Palma, while the second and the third are mounted at the Instituto de Astrofisica de Canarias 0.82-m telescope on Tenerife. We analyzed the presence and variability of dust structures in the coma with image-enhancing techniques, the radial profile of the dust brightness, and we measured the dust production rate and the dust reddening. Results. We found evidence of a long-lasting sunward fan and anti-solar tail activity throughout all our observations up to a heliocentric distance of 2.42 AU. Afρ measurements suggest a pre-perihelion peak of the activity, caused by a seasonal effect, plus two post-perihelion outbursts. Both spatial and Afρ radial profiles indicate a steady-state coma at nucleocentric distances greater than ~1000–2000 km. The color analysis reveals a moderately reddened dust with a 6–9%/1000 Å reddening, consistent with the current picture of cometary dust. The second outburst emitted dust with lower reddening. Conclusions. The comparison with previous perihelion passages points toward a recurrent main activity always driven by the same areas on the nucleus, producing dust with similar characteristics and in similar coma structures in different years. Our Afρ measurement at the longest heliocentric distance suggests the comet was less dust-productive in 2010, pointing toward a possible secular aging of the object and its activity. The change of dust colors during the unusual second outburst suggests that an internal part of the nucleus has different physical properties compared with those that produce the recurrent main activity, pointing toward a heterogeneous comet.

Item URL in elib:https://elib.dlr.de/103433/
Document Type:Article
Title:Photometric observations of comet 81P/Wild 2 during the 2010 perihelion passage
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Ho, T.-M.tra-mi.ho (at) dlr.deUNSPECIFIED
Barbieri, C.University of Padova, Padova, ItalyUNSPECIFIED
Date:May 2012
Journal or Publication Title:Astronomy & Astrophysics
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1051/0004-6361/201118004
Publisher:EDP Sciences
Keywords:comets: general / comets: individual: 81P/Wild 2 / techniques: photometric
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Project MASCOT (old)
Location: Bremen
Institutes and Institutions:Institute of Space Systems > Systems Engineering and Project Office
Deposited By: Behnke, Manuela
Deposited On:15 Mar 2016 09:59
Last Modified:08 Mar 2018 18:23

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