The nucleus of Comet 67P/Churyumov-Gerasimenko

Lowry, S. C.; Duddy, S. R.; Rozitis, B.; Green, Simon; Fitzsimmons, A.; Snodgrass, C.; Hsieh, Henry H.; Hainaut, Olivier

doi:10.1051/0004-6361/201220116

Cited by 60 publications

(69 citation statements)

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“…The dashed line shows a prediction for the total magnitude based on a water production rate model (see section 4.3), while the dotted lines show a power law fit to the data. age (V − R) = 0.53 ± 0.02 and (R − I) = 0.48 ± 0.02 (Lamy et al 2006;Tubiana et al 2008Tubiana et al , 2011Lowry et al 2012). This implies that the grains in the coma are smaller than the dominant surface grains, preferentially scattering bluer wavelengths.…”

Section: The Colour Of the Coma At Large Heliocentric Distancementioning

confidence: 97%

“…We therefore applied a correction to the photometry, by using the nucleus shape and pole model published by Lowry et al (2012) to calculate the predicted rotational lightcurve phase at the time of the observations, and the corresponding offset from the mean effective magnitude, as would be observed for a nonvarying (spherical) nucleus. As Lowry et al (2012) also use July 2007 data in their model, the uncertainty in the extrapolation of rotational phase is small (∼ 0.1% by November 2007). The corrections to the photometry due to rotation phase are at most 0.13 magnitudes (for the August 2007 data), and smaller than the uncertainties for all other months (Sep: -0.01 mag.…”

Section: Beginning Of Activitymentioning

confidence: 99%

“…Schulz et al (2004), Lamy et al (2006) and Lara et al (2005) obtained the first dedicated characterisation observations after it was selected, when the comet was on the outbound leg of its orbit, and still highly active, following its perihelion passage in 2002. As the comet passed through aphelion its inactive nucleus was studied by Tubiana et al (2008Tubiana et al ( , 2011 and Lowry et al (2012), before it was observed in an active state again as it returned to perihelion in 2008 (Tozzi et al 2011;Lara et al 2011). Further authors have studied the longer lived dust trail associated with the comet (Ishiguro 2008;Kelley et al 2008;Agarwal et al 2010), the dust's polarisation (Hadamcik et al 2010), the nucleus thermal properties (Kelley et al 2006;Lamy et al 2008;Kelley et al 2009), and the morphology (Vincent et al 2013) and composition (Schleicher 2006) of its coma over multiple apparitions.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper we present data taken in 2007 and 2008 around the time of the expected onset, between the inactive nucleus observations taken in 2007 (Tubiana et al 2011;Lowry et al 2012) and the active comet observations in 2008 (Tozzi et al 2011). 20 × 30 (0) R 27/3/08 3.39 3.80 14.6 3×15 + 4×60 (6) VRI 29/3/08 3.38 3.76 14.9 3×15 + 4×60 (6) VRI 30/3/08 3.38 3.74 15.0 3×15 + 4×60 (6) VRI (a) Heliocentric distance (AU).…”

Section: Introductionmentioning

confidence: 99%

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Beginning of activity in 67P/Churyumov-Gerasimenko and predictions for 2014–2015

Snodgrass

Tubiana

Bramich

et al. 2013

A&A

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Context. Comet 67P/Churyumov-Gerasimenko was selected in 2003 as the new target of the Rosetta mission. It has since been the subject of a detailed campaign of observations to characterise its nucleus and activity. Aims. Here we present previously unpublished data taken around the start of activity of the comet in 2007/8, before its last perihelion passage. We constrain the time of the start of activity, and combine this with other data taken throughout the comet's orbit to make predictions for its likely behaviour during 2014/5 while Rosetta is operating. Methods. A considerable difficulty in observing 67P during the past years has been its position against crowded fields towards the Galactic centre for much of the time. The 2007/8 data presented here were particularly difficult, and the comet will once again be badly placed for Earth-based observations in 2014/5. We make use of the difference image analysis (DIA) technique, which is commonly used in variable star and exoplanet research, to remove background sources and extract images of the comet. In addition, we reprocess a large quantity of archival images of 67P covering its full orbit, to produce a heliocentric lightcurve. By using consistent reduction, measurement and calibration techniques we generate a remarkably clean lightcurve, which can be used to measure a brightnessdistance relationship and to predict the future brightness of the comet. Results. We determine that the comet was active around November 2007, at a pre-perihelion distance from the Sun of 4.3 AU. The comet will reach this distance, and probably become active again, in March 2014. We find that the dust brightness can be well described by A f ρ ∝ r −3.2 pre-perihelion and ∝ r −3.4 post-perihelion, and that the comet has a higher dust-to-gas ratio than average, with log(A f ρ/Q(H 2 O)) = −24.94 ± 0.22 cm s molecule −1 at r < 2 AU. A model fit to the photometric data suggests that only a small fraction (1.4%) of the surface is active.

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Section: The Colour Of the Coma At Large Heliocentric Distancementioning

confidence: 97%

Section: Beginning Of Activitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Beginning of activity in 67P/Churyumov-Gerasimenko and predictions for 2014–2015

Snodgrass

Tubiana

Bramich

et al. 2013

A&A

Self Cite

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“…Rotational periods of several cometary nucleii have been obtained by means of time series photometry (Fay & Wisniewski 1978;Jewitt 1990;Meech et al 1997;Gutiérrez et al 2003;Snodgrass et al 2005Snodgrass et al , 2008Lamy et al 2005;Lowry et al 2012;Mottola et al 2014). This task is easier when the comet nucleus is not active and there is not a gas/dust coma (i.e.…”

Section: Introductionmentioning

confidence: 99%

Short-term variability of comet C/2012 S1 (ISON) at 4.8 AU from the Sun

Santos-Sanz

Ortiz

Morales

et al. 2015

A&A

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Context. We observed comet C/2012 S1 (ISON) during six nights in February 2013 when it was at 4.8 AU from the Sun. At this distance and time the comet was not very active and it was theoretically possible to detect photometric variations likely due to the rotation of the cometary nucleus. Aims. The goal of this work is to obtain differential photometry of the comet inner coma using different aperture radii in order to derive a possible rotational period. Methods. Large field of view images were obtained with a 4 k × 4 k CCD at the f/3 0.77 m telescope of La Hita Observatory in Spain. Aperture photometry was performed in order to get relative magnitude variation versus time. Using calibrated star fields we also obtained ISON's R-magnitudes versus time. We applied a Lomb-Scargle periodogram analysis to get possible periodicities for the observed brightness variations, directly related with the rotation of the cometary nucleus. Results. The comet light curve obtained is very shallow, with a peak-to-peak amplitude of 0.03 ± 0.02 mag. A tentative synodic rotational period (single-peaked) of 14.4 ± 1.2 h for ISON's nucleus is obtained from our analysis, but there are other possibilities. We studied the possible effect of the seeing variations in the obtained periodicities during the same night, and from night to night. These seeing variations had no effect on the derived periodicity. We discuss and interpret all possible solutions for the rotational period of ISON's nucleus.

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The Rosetta Cometary Mission: Launch and Target Comet

2014

Comets and Their Origin

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The nucleus of Comet 67P/Churyumov-Gerasimenko

Cited by 60 publications

References 40 publications

Beginning of activity in 67P/Churyumov-Gerasimenko and predictions for 2014–2015

Beginning of activity in 67P/Churyumov-Gerasimenko and predictions for 2014–2015

Short-term variability of comet C/2012 S1 (ISON) at 4.8 AU from the Sun

The Rosetta Cometary Mission: Launch and Target Comet

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