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

Pedro Henrique Hasselmann 1 Maria Antonella Barucci 1 Sonia Fornasier 1 D. Bockelée-Morvan 1 Prasanna Deshapriya 1 Clément Feller 1 Jessica Sunshine 2 V. Hoang 1, 3 H. Sierks 4 G. Naletto 5, 6, 7 Philippe Lamy 8, 9 R. Rodrigo 10, 11 D. Koschny 12 Björn Davidsson 13 Jean-Loup Bertaux 8 Ivano Bertini 6 Dennis Bodewits 14 Gabriele Cremonese 15 Vania da Deppo 16 Stefano Debei 17 Marco Fulle 18 Pedro J. Gutiérrez 19 Carsten Güttler 4 Jakob Deller 4 W.-H. Ip 20, 21 Horst Uwe Keller 22, 23 Luisa Maria Lara 19 M. de Cecco 24 Monica Lazzarin 14 J.J. López-Moreno 19 Francesco Marzari 6 X. Shi 4 Cécilia Tubiana 4
Abstract : 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 × 1024 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.
Document type :
Journal articles
Complete list of metadatas

Cited literature [82 references]  Display  Hide  Download

https://hal-insu.archives-ouvertes.fr/insu-02112890
Contributor : Catherine Cardon <>
Submitted on : Friday, September 20, 2019 - 2:58:42 PM
Last modification on : Thursday, October 10, 2019 - 2:48:02 PM

File

aa33940-18.pdf
Publisher files allowed on an open archive

Identifiers

Citation

Pedro Henrique Hasselmann, Maria Antonella Barucci, Sonia Fornasier, D. Bockelée-Morvan, Prasanna Deshapriya, et al.. Pronounced morphological changes in a southern active zone on comet 67P/Churyumov-Gerasimenko. Astronomy and Astrophysics - A&A, EDP Sciences, 2019, 630, A8 (19p.). ⟨10.1051/0004-6361/201833940⟩. ⟨insu-02112890⟩

Share

Metrics

Record views

134

Files downloads

22