Pre-perihelion activity of comet 67P/Churyumov-Gerasimenko

Guilbert-Lepoutre, A.; Schulz, R.; Rożek, A.; Lowry, S. C.; Tozzi, G. P.; Stüwe, J. A.

doi:10.1051/0004-6361/201424186

Cited by 17 publications

(14 citation statements)

References 33 publications

(42 reference statements)

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“…15) we see that there is a significant asymmetry around perihelion, with clear CN detections at the same distance outbound as stronger upper limits are measured inbound. Our data, together with previous VLT/FORS ob- servations taken pre-perihelion in 2008 by Guilbert-Lepoutre et al (2014), clearly show that we would be sensitive to production rates of order a few times 10 23 molecules s −1 at most distances, and no such activity was seen, even at close to 2 au inbound. Schulz et al (2004), meanwhile, detected CN at ∼ 2 × 10 24 molecules s −1 around 2.5 au post-perihelion in 2003, and still measured gas production close to 3 au.…”

Section: Discussionsupporting

confidence: 62%

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Distant activity of 67P/Churyumov-Gerasimenko in 2014: Ground-based results during the Rosetta pre-landing phase

Snodgrass

Jehin

Manfroid

et al. 2016

A&A

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Context. As the ESA Rosetta mission approached, orbited, and sent a lander to comet 67P/Churyumov-Gerasimenko in 2014, a large campaign of ground-based observations also followed the comet. Aims. We constrain the total activity level of the comet by photometry and spectroscopy to place Rosetta results in context and to understand the large-scale structure of the comet's coma pre-perihelion. Methods. We performed observations using a number of telescopes, but concentrate on results from the 8 m VLT and Gemini South telescopes in Chile. We use R-band imaging to measure the dust coma contribution to the comet's brightness and UV-visible spectroscopy to search for gas emissions, primarily using VLT/FORS. In addition we imaged the comet in near-infrared wavelengths (JHK) in late 2014 with Gemini-S/Flamingos-2. Results. We find that the comet was already active in early 2014 at heliocentric distances beyond 4 au. The evolution of the total activity (measured by dust) followed previous predictions. No gas emissions were detected despite sensitive searches. Conclusions. The comet maintains a similar level of activity from orbit to orbit, and is in that sense predictable, meaning that Rosetta results correspond to typical behaviour for this comet. The gas production (for CN at least) is highly asymmetric with respect to perihelion, as our upper limits are below the measured production rates for similar distances post-perihelion in previous orbits.

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Section: Discussionsupporting

confidence: 62%

“…Production rate of CN (molecules s −1 ). We include upper limits from this work (crossed circles) andGuilbert-Lepoutre et al 2014 (GL2014 -open circles), all pre-perihelion, together with postperihelion measurements fromSchulz et al 2004. Measurements from photometry(Schleicher 2006 are split into inbound (squares) and outbound (triangles).…”

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confidence: 99%

Distant activity of 67P/Churyumov-Gerasimenko in 2014: Ground-based results during the Rosetta pre-landing phase

Snodgrass

Jehin

Manfroid

et al. 2016

A&A

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“…CN production rate (in molecules s −1 ) as a function of heliocentric distance (negative values indicate pre-perihelion data, positive post-perihelion). We include data from previous orbits [3,7,12,73], narrowband photometry from TRAPPIST and the Lowell 1.1 m around perihelion, and spectroscopy from the VLT, SAO 6 m and LT (see key in plot for symbols). Error bars are not included for clarity.…”

Section: Total Activitymentioning

confidence: 99%

The 67P/Churyumov–Gerasimenko observation campaign in support of the Rosetta mission

Snodgrass

A’Hearn

Aceituno

et al. 2017

Phil. Trans. R. Soc. A.

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We present a summary of the campaign of remote observations that supported the European Space Agency's Rosetta mission. Telescopes across the globe (and in space) followed comet 67P/Churyumov-Gerasimenko from before Rosetta's arrival until nearly the end of the mission in September 2016. These provided essential data for mission planning, large-scale context information for the coma and tails beyond the spacecraft and a way to directly compare 67P with other comets. The observations revealed 67P to be a relatively 'well-behaved' comet, typical of Jupiter family comets and with activity patterns that repeat from orbit to orbit. Comparison between this large collection of telescopic observations and the results from Rosetta will allow us to better understand comet coma chemistry and structure. This work is just beginning as the mission ends-in this paper, we present a summary of the ground-based observations and early results, and point to many questions that will be addressed in future studies.This article is part of the themed issue 'Cometary science after Rosetta'.

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“…CN is the daughter molecule of HCN, which if present in the nucleus under a dusty crust, may not sublimate freely. If buried under a dusty crust, it would follow a diffusion regime, with a mass loss rate written as (assuming an ideal gas law, Fanale & Salvail 1984;Schorghofer 2008;Gundlach et al 2011;Guilbert-Lepoutre et al 2014)…”

Section: Modelling the Outburst And Activity Patternmentioning

confidence: 99%

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

Opitom

Guilbert-Lepoutre

Jehin

et al. 2016

A&A

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We present a unique data set of more than one year's worth of regular observations of comet C/2013 A1(Siding Spring) taken with TRAPPIST, 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-borne and ground-based telescopes. We followed the evolution of the OH, NH, CN, C 3 , and C 2 production rates as well as the A f ρ parameter, a proxy for the dust production. We detected an outburst two weeks after perihelion, with gas and dust production rates increased by a factor of five within a few days. By modelling the shape of the CN and C 2 radial profiles, we determined that the outburst happened on November 10 around 15:30 UT (±5 h) and measured a gas expansion velocity of 1.1 ± 0.2 km s −1 . 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, C 2 /OH, or 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.

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Pre-perihelion activity of comet 67P/Churyumov-Gerasimenko

Cited by 17 publications

References 33 publications

Distant activity of 67P/Churyumov-Gerasimenko in 2014: Ground-based results during the Rosetta pre-landing phase

Distant activity of 67P/Churyumov-Gerasimenko in 2014: Ground-based results during the Rosetta pre-landing phase

The 67P/Churyumov–Gerasimenko observation campaign in support of the Rosetta mission

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

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