Neutral and Plasma Distributions in the Coma of Comet C/2012 S1 ISON: Narrowband Imaging and Integral-Field Spectroscopy

Abstract : We present concurrent spectra and filtered imaging of the coma of C/2012 S1 ISON at .44 to 0.47 AU from the sun. C2, NH2, Na, and H2O+ distributions were elongated several thousand km along an axis perpendicular to the comet’s motion and the sunward vector. The peak brightness of each species was collocated within 5,000 km of the dusty continuum concentration. ISON’s water ion tail appeared distinctly broader than the neutral Na tail and we find no evidence for an extended source of Na by dissociative recombination of a molecular ion. Rather, an extended source of as much as 50% of Na may be attributed to dust, evidenced via Monte Carlo simulations of a distant sodium tail extending beyond 106 km. An increase of nearly a factor of four in the Na source rate was found within a 24 hour interval during an outburst, and the relative Na/O abundance is estimated at ~5 x 10-7, well below the ratio known in active comets of comparable geometry.
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https://hal-insu.archives-ouvertes.fr/insu-01216213
Contributor : Catherine Cardon <>
Submitted on : Thursday, October 15, 2015 - 5:13:03 PM
Last modification on : Wednesday, May 22, 2019 - 4:48:10 PM

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  • HAL Id : insu-01216213, version 1

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C. A. Schmidt, R. E. Johnson, François Leblanc, J. Baumgardner, M. Mendillo. Neutral and Plasma Distributions in the Coma of Comet C/2012 S1 ISON: Narrowband Imaging and Integral-Field Spectroscopy. European Planetary Science Congress 2015, Sep 2015, Nantes, France. pp.EPSC2015-315. ⟨insu-01216213⟩

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