A multi-wavelength study of parent volatile abundances in Comet C/2006 M4 (SWAN)

Michael A. DiSanti, Geronimo L. Villanueva, Stefanie N. Milam, Lindsay N. Zack, Boncho P. Bonev, Michael J. Mumma, Lucy M Ziurys, William M. Anderson

Research output: Contribution to journalArticle

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Abstract

Volatile organic emissions were detected post-perihelion in the long-period Comet C/2006 M4 (SWAN) in October and November 2006. Our study combines target-of-opportunity infrared observations using the Cryogenic Echelle Spectrometer (CSHELL) at the NASA-IRTF 3-m telescope, and millimeter wavelength observations using the Arizona Radio Observatory (ARO) 12-m telescope. Five parent volatiles were measured with CSHELL (H2O, CO, CH3OH, CH4, and C2H6), and two additional species (HCN and CS) were measured with the ARO 12-m. These revealed highly depleted CO and somewhat enriched CH3OH compared with abundances observed in the dominant group of long-period (Oort cloud) comets in our sample and similar to those observed recently in Comet 8P/Tuttle. This may indicate highly efficient H-atom addition to CO at very low temperature (∼10-20 K) on the surfaces of interstellar (pre-cometary) grains. Comet C/2006 M4 had nearly "normal" C2H6 and CH4, suggesting a processing history similar to that experienced by the dominant group. When compared with estimated water production at the time of the millimeter observations, HCN was slightly depleted compared with the normal abundance in comets based on IR observations but was consistent with the majority of values from the millimeter. The ratio CS/HCN in C/2006 M4 was within the range measured in ten comets at millimeter wavelengths. The higher apparent H-atom conversion efficiency compared with most comets may indicate that the icy grains incorporated into C/2006 M4 were exposed to higher H-atom densities, or alternatively to similar densities but for a longer period of time.

Original languageEnglish (US)
Pages (from-to)589-598
Number of pages10
JournalIcarus
Volume203
Issue number2
DOIs
StatePublished - Oct 2009

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comets
comet
wavelength
wavelengths
observatories
observatory
telescopes
Oort cloud
radio
atoms
cryogenics
spectrometer
histories
spectrometers
history
water

Keywords

  • Comets, Composition
  • Comets, Origin

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

DiSanti, M. A., Villanueva, G. L., Milam, S. N., Zack, L. N., Bonev, B. P., Mumma, M. J., ... Anderson, W. M. (2009). A multi-wavelength study of parent volatile abundances in Comet C/2006 M4 (SWAN). Icarus, 203(2), 589-598. https://doi.org/10.1016/j.icarus.2009.05.026

A multi-wavelength study of parent volatile abundances in Comet C/2006 M4 (SWAN). / DiSanti, Michael A.; Villanueva, Geronimo L.; Milam, Stefanie N.; Zack, Lindsay N.; Bonev, Boncho P.; Mumma, Michael J.; Ziurys, Lucy M; Anderson, William M.

In: Icarus, Vol. 203, No. 2, 10.2009, p. 589-598.

Research output: Contribution to journalArticle

DiSanti, MA, Villanueva, GL, Milam, SN, Zack, LN, Bonev, BP, Mumma, MJ, Ziurys, LM & Anderson, WM 2009, 'A multi-wavelength study of parent volatile abundances in Comet C/2006 M4 (SWAN)', Icarus, vol. 203, no. 2, pp. 589-598. https://doi.org/10.1016/j.icarus.2009.05.026
DiSanti MA, Villanueva GL, Milam SN, Zack LN, Bonev BP, Mumma MJ et al. A multi-wavelength study of parent volatile abundances in Comet C/2006 M4 (SWAN). Icarus. 2009 Oct;203(2):589-598. https://doi.org/10.1016/j.icarus.2009.05.026
DiSanti, Michael A. ; Villanueva, Geronimo L. ; Milam, Stefanie N. ; Zack, Lindsay N. ; Bonev, Boncho P. ; Mumma, Michael J. ; Ziurys, Lucy M ; Anderson, William M. / A multi-wavelength study of parent volatile abundances in Comet C/2006 M4 (SWAN). In: Icarus. 2009 ; Vol. 203, No. 2. pp. 589-598.
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abstract = "Volatile organic emissions were detected post-perihelion in the long-period Comet C/2006 M4 (SWAN) in October and November 2006. Our study combines target-of-opportunity infrared observations using the Cryogenic Echelle Spectrometer (CSHELL) at the NASA-IRTF 3-m telescope, and millimeter wavelength observations using the Arizona Radio Observatory (ARO) 12-m telescope. Five parent volatiles were measured with CSHELL (H2O, CO, CH3OH, CH4, and C2H6), and two additional species (HCN and CS) were measured with the ARO 12-m. These revealed highly depleted CO and somewhat enriched CH3OH compared with abundances observed in the dominant group of long-period (Oort cloud) comets in our sample and similar to those observed recently in Comet 8P/Tuttle. This may indicate highly efficient H-atom addition to CO at very low temperature (∼10-20 K) on the surfaces of interstellar (pre-cometary) grains. Comet C/2006 M4 had nearly {"}normal{"} C2H6 and CH4, suggesting a processing history similar to that experienced by the dominant group. When compared with estimated water production at the time of the millimeter observations, HCN was slightly depleted compared with the normal abundance in comets based on IR observations but was consistent with the majority of values from the millimeter. The ratio CS/HCN in C/2006 M4 was within the range measured in ten comets at millimeter wavelengths. The higher apparent H-atom conversion efficiency compared with most comets may indicate that the icy grains incorporated into C/2006 M4 were exposed to higher H-atom densities, or alternatively to similar densities but for a longer period of time.",
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AB - Volatile organic emissions were detected post-perihelion in the long-period Comet C/2006 M4 (SWAN) in October and November 2006. Our study combines target-of-opportunity infrared observations using the Cryogenic Echelle Spectrometer (CSHELL) at the NASA-IRTF 3-m telescope, and millimeter wavelength observations using the Arizona Radio Observatory (ARO) 12-m telescope. Five parent volatiles were measured with CSHELL (H2O, CO, CH3OH, CH4, and C2H6), and two additional species (HCN and CS) were measured with the ARO 12-m. These revealed highly depleted CO and somewhat enriched CH3OH compared with abundances observed in the dominant group of long-period (Oort cloud) comets in our sample and similar to those observed recently in Comet 8P/Tuttle. This may indicate highly efficient H-atom addition to CO at very low temperature (∼10-20 K) on the surfaces of interstellar (pre-cometary) grains. Comet C/2006 M4 had nearly "normal" C2H6 and CH4, suggesting a processing history similar to that experienced by the dominant group. When compared with estimated water production at the time of the millimeter observations, HCN was slightly depleted compared with the normal abundance in comets based on IR observations but was consistent with the majority of values from the millimeter. The ratio CS/HCN in C/2006 M4 was within the range measured in ten comets at millimeter wavelengths. The higher apparent H-atom conversion efficiency compared with most comets may indicate that the icy grains incorporated into C/2006 M4 were exposed to higher H-atom densities, or alternatively to similar densities but for a longer period of time.

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