Comet C/2011 J2 (LINEAR) nucleus splitting: Dynamical and structural analysis

• Published in: Planetary and space science Vol. 126; pp. 8 - 23
• Main Authors: Manzini, Federico, Oldani, Virginio, Hirabayashi, Masatoshi, Behrend, Raoul, Crippa, Roberto, Ochner, Paolo, Pina, Jose Pablo Navarro, Haver, Roberto, Baransky, Alexander, Bryssinck, Eric, Dan, Andras, De Queiroz, Jose, Frappa, Eric, Lavayssiere, Maylis
• Format: Journal Article
• Language: English
• Published: 01.07.2016
• Subjects: Breakup; Comet nuclei; Comets; Fragmentation; Mathematical analysis; Perihelions; Photometry; Structural analysis
• ISSN: 0032-0633
• DOI: 10.1016/j.pss.2016.04.004

After the discovery of the breakup event of comet C/2011 J2 in August 2014, we followed the primary body and the main fragment B for about 120 days in the context of a wide international collaboration. From the analysis of all published magnitude estimates we calculated the comet's absolute magnitude H=10.4, and its photometric index n=1.7. We also calculated a water production of only 110kg/s at the perihelion. These values are typical of a low-activity, long-period or new comet. Analysis of the motion of fragment B over the observation period showed that the first breakout event likely occurred between 12 July and 30 July 2014. Nucleus B remained persistently visible throughout the 4-month observation period. The projected separation velocity of nucleus B from the parent body was 4.22m/s at the time of the breakup and 12.7m/s at the end of the observation period, suggesting that nucleus B was subjected to a constant deceleration . The spin period of the main nucleus was estimated as 4.56h plus or minus 0.05h by photometric analysis. The structural analysis of the comet showed a cohesive strength of the nucleus greater than ~0.9kPa; assuming a bulk density of 500kg/m3, with a rotation period of 4.56h the cometary nucleus might have failed structurally, especially if the body was elongated. These results suggest that the nucleus of comet C/2011 J2 has an elongated shape, with a ratio of the semi-minor axis to the semi-major axis ; the semi-major axis of the pristine nucleus could be larger than 8km. From this study, we propose that rotational disruption, possibly combined with sublimation pressure, was a reasonable explanation for the breakup event in comet C/2011 J2.