A mini outburst from the nightside of comet 67P/Churyumov-Gerasimenko observed by the OSIRIS camera on Rosetta

Knollenberg, J.; Lin, Z. Y.; Hviid, S. F.; Oklay, N.; Vincent, J.-B.; Bodewits, Dennis; Mottola, S.; Pajola, M.; Sierks, H.; Barbieri, C.; Lamy, Philippe; Rodrigo, R.; Koschny, D.; Rickman, H.; A’Hearn, Michael F.; Barucci, M. A.; Bertaux, Jean-Loup; Bertini, Ivano; Cremonese, G.; Davidsson, B.; Deppo, Vania Da; Debei, S.; Cecco, M. De; Fornasier, S.; Fulle, M.; Groussin, O.; Gutiérrez, P. J.; Ip, W. H.; Jordá, L.; Keller, H. U.; Kührt, Ekkehard; Kramm, J. R.; Küppers, M.; Lara, L. M.; Lazzarin, M.; Moreno, J. J. Lopez; Marzari, F.; Naletto, G.; Thomas, N.; Güttler, C.; Preusker, Frank; Scholten, F.; Tubiana, C.

doi:10.1051/0004-6361/201527744

Cited by 34 publications

(19 citation statements)

References 25 publications

(25 reference statements)

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“…Mass loss in 67P outbursts. Presently published estimations of the dust mass emitted in 67P outbursts are mainly derived from optical images obtained less than a few minutes after outburst onset (Knollenberg et al 2016;Vincent et al 2016b). These estimations make the assumption of a dust size distribution and geometric albedo similar to the quiescent coma values.…”

Section: Summary and Discussionmentioning

confidence: 99%

Comet 67P outbursts and quiescent coma at 1.3 au from the Sun: dust properties from Rosetta/VIRTIS-H observations

Bockelée‐Morvan

Rinaldi

Erard

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present 2-5 µm spectroscopic observations of the dust coma of 67P/Churyumov-Gerasimenko obtained with the VIRTIS-H instrument onboard Rosetta during two outbursts that occurred on 2015, 13 September 13.6 h UT and 14 September 18.8 h UT at 1.3 AU from the Sun. Scattering and thermal properties measured before the outburst are in the mean of values measured for moderately active comets. The colour temperature excess (or superheat factor) can be attributed to submicrometresized particles composed of absorbing material or to porous fractal-like aggregates such as those collected by the Rosetta in situ dust instruments. The power law index of the dust size distribution is in the range 2-3. The sudden increase of infrared emission associated to the outbursts is correlated with a large increase of the colour temperature (from 300 K to up to 630 K) and a change of the dust colour at 2-2.5 µm from red to blue colours, revealing the presence of very small grains (≤ 100 nm) in the outburst material. In addition, the measured large bolometric albedos (∼ 0.7) indicate bright grains in the ejecta, which could either be silicatic grains, implying the thermal degradation of the carbonaceous material, or icy grains. The 3-µm absorption band from water ice is not detected in the spectra acquired during the outbursts, whereas signatures of organic compounds near 3.4 µm are observed in emission. The H 2 O 2.7-µm and CO 2 4.3-µm vibrational bands do not show any enhancement during the outbursts.

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Section: Summary and Discussionmentioning

confidence: 99%

Comet 67P outbursts and quiescent coma at 1.3 au from the Sun: dust properties from Rosetta/VIRTIS-H observations

Bockelée‐Morvan

Rinaldi

Erard

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…Therefore, the formula represents the minimum molecular gas production rate that some local activity, outburst, or event need to at least detach the spherical object from the ground. By way of comparison, El-Maarry et al (2017) reported for 8.5 × 10 23 m −2 s −1 for jumping boulder 1, while a theoretical range of 5 × 10 21 m −2 s −1 (Knollenberg et al 2016) to 1.1 × 10 24 m −2 s −1 (Agarwal et al 2017) has been reported for some outbursts. During the perihelion passage of mid-to-end 2015, the peaking H 2 O production was 5.88 × 10 20 m −2 s −1 (Lai et al 2016).…”

Section: Minimum Lifting Gas Production Ratementioning

confidence: 96%

Pronounced morphological changes in a southern active zone on comet 67P/Churyumov-Gerasimenko

Hasselmann

Barucci

Fornasier

et al. 2019

A&A

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A smooth deposit in the southern Khonsu region has been seen in ESA/Rosetta observations as active during the second half of 2015, when the southern summer coincided with the perihelion passage of 67P/Churyumov-Gerasimenko (67P). Image color sequences acquired by the OSIRIS instrument in the period of January 2015 to July 2016, pre-and post-perihelion, show the occurrence of several small transient events as well as three massive outbursts (∼10 to 1500 tons). High spatial resolution images taken one year and a half apart allowed us to track a variety of sources: the formation of cavities that are 1.3-14 m deep, ice-enriched patches, scarp retraction, and a second 50 m-wide boulder. We then estimated their masses and the dust mass of their corresponding plumes and outbursts. In particular, the deformation left by that boulder and its lack of talus may provide evidence for the lifting and subsequent falling back to the surface of large blocks. We calculate that a minimum vapor production rate of 1.4 × 10 24 m −2 s −1 is required to lift such an object. The comparison of the masses that are lost in the new cavities to the dust mass of outbursts gives indirect evidence of highly volatile ice pockets underneath. The spectrophotometric analysis and boulder counting also provides evidence for cavities that formed only 30 m apart with different spectral slopes, two long-standing ice patches, and local variations in the boulder-size frequency distribution. All this points to sub-surface ice pockets with different degrees of depth. Finally, the total mass of the morphological changes compared to most recent calculations of the total released mass by activity on 67P is estimated to be between 1.5 and 4.2%. This means that as many as about 25 similar active zones across the nucleus would be enough to sustain the entire cometary activity.

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“…2P/Encke, Levison et al (2006)). Outbursts of 67P/Churyumov-Gerasimenko were discussed by Knollenberg et al (2016) and Vincent et al (2016) but an unambiguous mechanism could not be identified. The distances at which outbursts occur also vary and the different comets can provide clues as to what drives activity.…”

Section: Outburst Duration and Mechanismsmentioning

confidence: 99%

Detailed characterization of low activity comet 49P/Arend–Rigaux

Chu

Meech

Farnham

et al. 2020

Icarus

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Comet 49P/Arend-Rigaux is a well known low-activity Jupiter Family comet. Despite the low activity, we have witnessed outgassing activity in 1992, 2004, and 2012. In 2012 a broad tail-like feature (PA∼270 • , ∼2.3×10 5 km) and a narrow jet-like feature (PA∼180 • , ∼9.3×10 4 km) were seen simultaneously. Using Finson-Probstein (FP) dust dynamical models we determine: the grain sizes released in each event; the duration of activity; when the activity peaked; and the velocity of the dust particles, allowing us to make comparisons between the events. We find that the tail feature in 2012 is similar to the tail in 1992 with large grains (40-4000 µm) peaking in activity around perihelion with a long duration of outgassing greater than 150 days. The jet feature from 2012, however, is more similar to the 2004 event which we model with small grains (1-8 µm) with a short duration of activity on the order of one month. The main difference between these two features is that the 2004 event occurs prior to perihelion, while the 2012 event is post-perihelion. We use the grain sizes from the FP models to constrain ice sublimation models. Between 1985 and 2018 we cover six apparitions with 26 nights of our own observations, data from the literature, and data from the Minor Planet Center, which together, allow us to model the heliocentric light curve. We find that the models are consistent with H 2 O ice sublimation as the volatile responsible for driving activity over most of the active phases and a combination of H 2 O and CO 2 ices are responsible for driving activity near perihelion. We measure the fractional active area over time for H 2 O and discover that the activity decreases from an average active area of ∼ 3% to ∼ 0.2%. This clear secular decrease in activity implies that the comet is becoming depleted of volatiles and is in the process of transitioning to either a dormant or dead state.

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A mini outburst from the nightside of comet 67P/Churyumov-Gerasimenko observed by the OSIRIS camera on Rosetta

Cited by 34 publications

References 25 publications

Comet 67P outbursts and quiescent coma at 1.3 au from the Sun: dust properties from Rosetta/VIRTIS-H observations

Comet 67P outbursts and quiescent coma at 1.3 au from the Sun: dust properties from Rosetta/VIRTIS-H observations

Pronounced morphological changes in a southern active zone on comet 67P/Churyumov-Gerasimenko

Detailed characterization of low activity comet 49P/Arend–Rigaux

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