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Temporal and Spatial Aspects of Gas Release During the 2010 Apparition of Comet 103P/Hartley 2

Mumma, M. J. and Bonev, B. P. and Villanueva, G. L. and Paganini, L. and DiSanti, M. A. and Gibb, E. L. and Keane, J. V. and Meech, K. J. and Blake, G. A. and Ellis, R. S. and Lippi, M. and Boehnhardt, H. and Magee-Sauer, K. (2011) Temporal and Spatial Aspects of Gas Release During the 2010 Apparition of Comet 103P/Hartley 2. Astrophysical Journal Letters, 734 (1). Art. No. L7. ISSN 2041-8205.

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We report measurements of eight primary volatiles (H_(2)O, HCN, CH_4, C_(2)H_6, CH_(3)OH, C_(2)H_2, H_(2)CO, and NH_3) and two product species (OH and NH_2) in comet 103P/Hartley 2 using high-dispersion infrared spectroscopy. We quantified the long- and short-term behavior of volatile release over a three-month interval that encompassed the comet's close approach to Earth, its perihelion passage, and flyby of the comet by the Deep Impact spacecraft during the EPOXI mission. We present production rates for individual species, their mixing ratios relative to water, and their spatial distributions in the coma on multiple dates. The production rates for water, ethane, HCN, and methanol vary in a manner consistent with independent measures of nucleus rotation, but mixing ratios for HCN, C_(2)H_6, and CH_(3)OH are independent of rotational phase. Our results demonstrate that the ensemble average composition of gas released from the nucleus is well defined and relatively constant over the three-month interval (September 18 through December 17). If individual vents vary in composition, enough diverse vents must be active simultaneously to approximate (in sum) the bulk composition of the nucleus. The released primary volatiles exhibit diverse spatial properties which favor the presence of separate polar and apolar ice phases in the nucleus, establish dust and gas release from icy clumps (and from the nucleus), and provide insights into the driver for the cyanogen (CN) polar jet. The spatial distributions of C_(2)H_6 and HCN along the near-polar jet (UT October 19.5) and nearly orthogonal to it (UT October 22.5) are discussed relative to the origin of CN. The ortho-para ratio (OPR) of water was 2.85 ± 0.20; the lower bound (2.65) defines T_spin > 32 K. These values are consistent with results returned from the Infrared Space Observatory in 1997.

Item Type:Article
Related URLs:
URLURL TypeDescription
Meech, K. J.0000-0002-2058-5670
Blake, G. A.0000-0003-0787-1610
Ellis, R. S.0000-0001-7782-7071
Additional Information:© 2011 American Astronomical Society. Received 2011 March 4; accepted 2011 April 4; published 2011 May 16. Based on data collected at the W. M. Keck Observatory, Mauna Kea, Hawaii, and at ESO’s Very Large Telescope, Paranal, Chile, under program 085.C-0229(A). Keck telescope time was granted by NOAO (through the Telescope System Instrumentation Program funded by NSF), the University of Hawaii, and the California Institute of Technology. VLT time was granted by the European Southern Observatory. We gratefully acknowledge support by the NSF Astronomy and Astrophysics Research Grants Program (PI/co-PI Bonev/Gibb), by the NASA Astrobiology Institute (PI: Meech, PI: Mumma), by NASA’s Planetary Astronomy (PI: DiSanti; PI: Mumma), Planetary Atmospheres (PI: DiSanti; PI: Villanueva), and Discovery (Meech) Programs, and by the German–Israel Foundation (D. Prialnik; M. Lippi).
Funding AgencyGrant Number
German-Israeli Foundation for Research and DevelopmentUNSPECIFIED
Subject Keywords:comets: general; comets: individual (103P/Hartley 2); infrared: planetary systems
Issue or Number:1
Classification Code:PACS: 96.30.Cw; 96.25.Hs
Record Number:CaltechAUTHORS:20110829-105937924
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Official Citation:Temporal and Spatial Aspects of Gas Release During the 2010 Apparition of Comet 103P/Hartley 2 M. J. Mumma et al. 2011 ApJ 734 L7
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25146
Deposited By: Jason Perez
Deposited On:01 Sep 2011 21:10
Last Modified:31 Oct 2019 03:51

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