TEMPORAL AND SPATIAL ASPECTS OF GAS RELEASE DURING THE 2010 APPARITION OF COMET 103P/HARTLEY 2

Journal Article · Fri Jun 10 00:00:00 EDT 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/734/1/L7· OSTI ID:21562626

Mumma, M J; Bonev, B P; Villanueva, G L; Paganini, L; DiSanti, M A ^[1]; Gibb, E L ^[2]; Keane, J V; Meech, K J ^[3]; Blake, G A ^[4]; Ellis, R S ^[5]; Lippi, M; Boehnhardt, H ^[6]; Magee-Sauer, K ^[7]

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1. Goddard Center for Astrobiology, NASA GSFC, MS 690.3, Greenbelt, MD 20771 (United States)
2. Department of Physics and Astronomy, University of Missouri, St. Louis, MO 63121 (United States)
3. Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)
4. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)
5. Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)
6. Max Planck Institute for Solar System Research, DE 37191 Katlenburg-Lindau (Germany)
7. Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028-1701 (United States)

We report measurements of eight primary volatiles (H{sub 2}O, HCN, CH{sub 4}, C{sub 2}H{sub 6}, CH{sub 3}OH, C{sub 2}H{sub 2}, H{sub 2}CO, and NH{sub 3}) and two product species (OH and NH{sub 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{sub 2}H{sub 6}, and CH{sub 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{sub 2}H{sub 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{sub spin} > 32 K. These values are consistent with results returned from the Infrared Space Observatory in 1997.

• OSTI ID: 21562626
• Journal Information: Astrophysical Journal Letters, Vol. 734, Issue 1; Other Information: DOI: 10.1088/2041-8205/734/1/L7; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
AMMONIA
COMETS
CYANOGEN
DIMETHYL SULFIDE
DUSTS
ETHANE
HYDROCYANIC ACID
INFRARED SPECTRA
METHANE
METHANOL
MIXING RATIO
SPATIAL DISTRIBUTION
VOLATILITY
WATER
ALCOHOLS
ALKANES
CHALCOGENIDES
DIMENSIONLESS NUMBERS
DISTRIBUTION
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INORGANIC ACIDS
INORGANIC COMPOUNDS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXYGEN COMPOUNDS
SPECTRA
SULFIDES
SULFUR COMPOUNDS