Uncorrelated Volatile Behavior During the 2011 Apparition of Comet C/2009 P1 Garradd

Abstract

The High Resolution Instrument Infrared Spectrometer (HRI-IR) onboard the Deep Impact Flyby spacecraft detected H2O, CO2, and CO in the coma of the dynamically young Oort cloud comet C/2009 P1 (Garradd) post-perihelion at a heliocentric distance of 2 AU. Production rates were derived for the parent volatiles, QH2O = 4.6e28, QCO2 = 3.9e27, and QCO = 2.9e28 molecules s-1, and are consistent with the trends seen by other observers and within the error bars of measurements acquired during a similar time period. When compiled with other observations of the dominant volatiles of Garradd, unexpected behavior was seen in the release of CO. The H2O outgassing of Garradd, increasing and peaking pre-perihelion and then steadily decreasing, is more typical than that of CO, which monotonically increased throughout the entire apparition. Due to the temporal asymmetry in volatile release, Garradd exhibited the highest CO to H2O abundance ratio ever observed for any comet inside the water snow line at 60 percent during the HRI-IR observations. Also, the HRI-IR made the only direct measurement of CO2, giving a typical cometary abundance ratio of CO2 to H2O of 8 percent but, with only one measurement, no sense of how it varied with orbital position.

38 pages, 10 figures, 5 tables, accepted for publication in The Astronomical Journal

References in corpus (2)

• Ice Lines, Planetesimal Composition and Solid Surface Density in the Solar Nebula
• The Fourth Positive System of Carbon Monoxide in the Hubble Space Telescope Spectra of Comets

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• The Main Belt Comets and Ice in the Solar System
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• Evolution of H${}_2$O, CO, and CO${}_2$ Production in Comet C/2009 P1 Garradd During the 2011-2012 Apparition
• Compact pebbles and the evolution of volatiles in the interstellar comet 2I/Borisov
• Cometary Science with the James Webb Space Telescope
• Searches for HCl and HF in comets 103P/Hartley 2 and C/2009 P1 (Garradd) with the Herschel space observatory
• The pre-perihelion activity of dynamically new comet C/2013 A1 (Siding Spring) and its close encounter with Mars
• Far-ultraviolet Spectroscopy of Recent Comets with the Cosmic Origins Spectrograph on the Hubble Space Telescope
• Ice-Coated Pebble Drift as a Possible Explanation for Peculiar Cometary CO/H2O Ratios
• Perihelion Asymmetry in the Water Production Rate of the Interstellar Object 3I/ATLAS
• Small Bodies Science with Twinkle
• $\text{Herschel}$/SPIRE Observations of Water Production Rates and Ortho-to-Para Ratios in Comets
• Volatile-rich comets ejected early on during Solar System formation
• Comet 240P/NEAT is Stirring
• A link between the size and composition of comets
• Pre-perihelion Volatile Evolution of Interstellar Comet 3I/ATLAS Indicating Significant Contribution from Extended Source in the Coma