Long-term activity and outburst of comet C/2013 A1 (Siding Spring) from narrow-band photometry and long-slit spectroscopy

Abstract

In this paper, we present a unique data set of more than one year's worth of regular observations of comet C/2013 A1(Siding Spring) with TRAPPIST in Chile, along with low-resolution spectra obtained with the ESO/VLT FORS 2 instrument. The comet made a close approach to Mars on October 19, 2014 and was then observed by many space and ground-based telescopes. We followed the evolution of the OH, NH, CN, ${\mathrm{C}}_3$, and ${\mathrm{C}}_2$ production rates as well as the $Af\rho$ parameter as a proxy for the dust production. We detected an outburst two weeks after perihelion, with gas and dust production rates being multiplied by a factor five within a few days. By modelling the shape of the CN and ${\mathrm{C}}_2$ radial profiles, we determined that the outburst happened around on November 10 around 15:30 UT ($\pm$ 5h) and measured a gas ejection velocity of $1.1\pm 0.2$ km/s. We used a thermal evolution model to reproduce the activity pattern and outburst. Our results are consistent with the progressive formation of a dust mantle explaining the shallow dependence of gas production rates, which may be partially blown off during the outburst. We studied the evolution of gas composition, using various ratios such as CN/OH, ${\mathrm{C}}_2$/OH, or ${\mathrm{C}}_3$/OH, which showed little or no variation with heliocentric distance including at the time of the outburst. This indicates a relative level of homogeneity of the nucleus composition.

arXiv commentSubmitted to Astronomy and Astrophysics

References in corpus (9)

• Micrometer-sized ice particles for planetary-science experiments - I. Preparation, critical rolling friction force, and specific surface energy
• The Evolving Activity of the Dynamically Young Comet C/2009 P1 (Garradd)
• Cometary water expansion velocity from OH line shapes
• SuperWASP Observations of the 2007 Outburst of Comet 17P/Holmes
• Outburst of Comet 17P/Holmes Observed With The Solar Mass Ejection Imager
• A Study of Dust and Gas at Mars from Comet C/2013 A1 (Siding Spring)
• Constraining the Dust Coma Properties of Comet C/Siding Spring (2013 A1) at Large Heliocentric Distances
• The pre-perihelion activity of dynamically new comet C/2013 A1 (Siding Spring) and its close encounter with Mars
• NEOWISE observations of comet C/2013 A1 (Siding Spring) as it approaches Mars

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