Stardust-NExT, Deep Impact, and the accelerating spin of 9P/Tempel 1

Belton, M. J. S.; Meech, К. J.; Chesley, Steven R.; Pittichová, J.; Carcich, B.; Drahus, M.; Harris, Alan W.; Gillam, S. D.; Veverka, J.; Mastrodemos, N.; Owen, W. M.; A’Hearn, Michael F.; Bagnulo, S.; Bai, J. M.; Barrera, L.; Bastien, Fabienne A.; Bauer, J. M.; Bedient, J.; Bhatt, B. C.; Boehnhardt, H.; Brosch, Noah; Buie, M. W.; Candia, P.; Chen, W. P.; Chiang, P. S.; Choi, Young Jun; Cochran, A. L.; Crockett, Christopher; Duddy, S. R.; Farnham, T. L.; Fernández, Y. R.; Gutiérrez, P. J.; Hainaut, Olivier; Hampton, Donald; Herrmann, Kimberly A.; Hsieh, Henry H.; Kadooka, M. A.; Kaluna, H. M.; Keane, J. V.; Kim, M. J.; Klaasen, K. P.; Kleyna, Jan; Krisciunas, K.; Lara, L. M.; Lauer, Tod R.; Li, Jian‐Yang; Licandro, J.; Lisse, C. M.; Lowry, S. C.; McFadden, L. A.; Moskovitz, Nicholas; Mueller, B. E. A.; Polishook, David; Raja, N. S.; Riesen, T.; Sahu, D. K.; Samarasinha, Nalin H.; Sarid, Gal; Sekiguchi, T.; Sonnett, S.; Suntzeff, Nicholas B.; Taylor, B.; Thomas, P. C.; Tozzi, G. P.; Vasundhara, R.; Vincent, J. B.; Wasserman, L. H.; Webster-Schultz, Bryant; Yang, Bin; Zenn, T.; Zhao, H. B.

doi:10.1016/j.icarus.2011.01.006

Cited by 48 publications

(54 citation statements)

References 42 publications

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“…No significant change in the rotation axis itself has been detected, although the bi-lobate nucleus Article published by EDP Sciences L5, page 1 of 4 is very ragged. It is expected that the rotation period will rapidly drop during the perihelion passage, in agreement with the previous perihelion passage, which is behavior similar to what was derived for Comet 9P/Tempel 1 (Belton et al 2011). Keller et al (2015) calculated the water production rate variation of 67P using the detailed SHAP4 shape model of the nucleus (Preusker et al 2015) derived from images taken by the scientific imager OSIRIS onboard Rosetta (Keller et al 2007).…”

Section: Introductionsupporting

confidence: 66%

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The changing rotation period of comet 67P/Churyumov-Gerasimenko controlled by its activity

Keller

Mottola

Skorov

et al. 2015

A&A

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Context. The ESA Rosetta spacecraft has been orbiting the nucleus of comet 67P/Churyumov-Gerasimenko since August 2014. The rotation axis of the irregularly shaped nucleus has a large obliquity (52 • ) and is oriented such that the southern hemisphere is insolated during perihelion. Aims. We calculate the change in the rotation period as a function of the cometary orbital position due to forces exerted by cometary activity. Methods. We used a detailed shape model of 67P with >10 5 facets. We calculated the efficiency of the facets to exert a torque based on their radial distance from the center of mass and their orientation. We applied our thermal model to calculate the diurnal water-ice sublimation rate from each facet. The reaction force per facet combined with its torque efficiency creates a torque and changes the angular momentum. The component of the torque parallel to the spin axis changes the rotation period. Results. Our model shows that the rotation period increases slightly during the approach of the comet to the Sun. It reaches a maximum shortly before equinox and drops rapidly during perihelion passage. The magnitude of the change depends on the actual sublimation rates. The change in sign mainly depends on the shape of the nucleus and not much on the sublimation variation. The roughness of the nucleus has little influence. Conclusions. For the given geometry of the rotation axis, the change in the rotation period is mainly influenced by the sublimation activity of the irregular shape of the nucleus. The rotation period increases until shortly before equinox in early May 2015, in good agreement with observations, and will then become shorter rapidly.

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Section: Introductionsupporting

confidence: 66%

“…The spin-up of cometary nuclei is probably the most plausible reason for cometary splitting (Jewitt 1997). Belton et al (2011) determined the variation in the rotation rate of comet 9P/Tempel 1 from thousands of ground-based and spacecraft observations. They could even determine the variation in the spin acceleration.…”

Section: Introductionmentioning

confidence: 99%

The changing rotation period of comet 67P/Churyumov-Gerasimenko controlled by its activity

Keller

Mottola

Skorov

et al. 2015

A&A

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“…As the comet's activity is largely similar from orbit to orbit (Snodgrass et al 2013), and 9P was seen to have a similar change in period each perihelion (Belton et al 2011), we can expect that the comet's period will decrease by a further ∼20 min during the coming perihelion passage. With the high precision on ∆P possible by landmark tracking from OSIRIS images, a change of this magnitude will be easy to detect, and furthermore the rate of change as the comet approaches the Sun will be determined, giving us information on the moment of inertia and torques due to outgassing at different times.…”

Section: Discussionmentioning

confidence: 91%

“…Four previous determinations of period changes in short period comets have been made, with magnitudes between 16 seconds per orbit for the low activity comet 10P/Tempel 2 (Knight et al 2012) and 2 h for the hyperactive 103P/Hartley 2 ). The other measurements were for 2P/Encke (4 min - Mueller et al 2008) and 9P/Tempel 1 (14 min - Belton et al 2011;Chesley et al 2013). It is not surprising that the change for 67P is similar to that for 9P, a comet of similar size and activity level, although with a considerably longer rotation period (41 h).…”

Section: Discussionmentioning

confidence: 92%

The rotation state of 67P/Churyumov-Gerasimenko from approach observations with the OSIRIS cameras on Rosetta

Mottola¹,

Lowry

Snodgrass

et al. 2014

A&A

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Aims. Approach observations with the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) experiment onboard Rosetta are used to determine the rotation period, the direction of the spin axis, and the state of rotation of comet 67P's nucleus. Methods. Photometric time series of 67P have been acquired by OSIRIS since the post wake-up commissioning of the payload in March 2014. Fourier analysis and convex shape inversion methods have been applied to the Rosetta data as well to the available ground-based observations. Results. Evidence is found that the rotation rate of 67P has significantly changed near the time of its 2009 perihelion passage, probably due to sublimation-induced torque. We find that the sidereal rotation periods P 1 = 12.76129 ± 0.00005 h and P 2 = 12.4043 ± 0.0007 h for the apparitions before and after the 2009 perihelion, respectively, provide the best fit to the observations. No signs of multiple periodicity are found in the light curves down to the noise level, which implies that the comet is presently in a simple rotation state around its axis of largest moment of inertia. We derive a prograde rotation model with spin vector J2000 ecliptic coordinates λ = 65• ± 15• , corresponding to equatorial coordinates RA = 22• , Dec = +76• . However, we find that the mirror solution, also prograde, at λ = 275• ), is also possible at the same confidence level, due to the intrinsic ambiguity of the photometric problem for observations performed close to the ecliptic plane.

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“…C/1990 K1 (Levy), C/2001 K5 (LINEAR), 2P/Encke, 6P/d'Arrest, 10P/Tempel 1), the first unequivocal measurement of a slow decrease in the rotation period was obtained only recently for comet 9P/Tempel 1 (Belton & Drahus 2007;Belton et al 2011). Model computations (e.g.…”

Section: Introductionmentioning

confidence: 99%

Rotation-stimulated structures in the CN and C₃comae of comet 103P/Hartley 2 close to the EPOXI encounter

Waniak

Borisov

Drahus

et al. 2012

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Context. In late 2010, a Jupiter family comet 103P/Hartley 2 was the subject of an intensive world-wide investigation. On UT October 20.7, the comet approached the Earth within only 0.12 AU, and on UT November 4.6 it was visited by the NASA EPOXI spacecraft. Aims. We joined this international effort and organized a ground-based observing campaign with three key goals to: (1) measure the parameters of the nucleus rotation in a time series of CN; (2) investigate the compositional structure of the coma by comparing the CN images with nightly snapshots of C 3 ; and (3) investigate the photochemical relation of CN to HCN, using the HCN data collected nearly simultaneously with our images. Methods. The images were obtained through narrowband filters using the two-meter telescope of the Rozhen National Astronomical Observatory. They were taken over four nights about the moment of the EPOXI encounter. Image processing methods and periodicity analysis techniques were used to identify transient coma structures and investigate their repeatability and kinematics. Results. We observe shells, arc-, jet-and spiral-like patterns that are very similar for the CN and C 3 comae. The CN features expanded outwards with the sky-plane projected velocities of between 0.1 to 0.3 km s −1 . A corkscrew structure, observed on November 6, evolved with a much higher velocity of 0.66 km s −1 . The photometry of the inner coma of CN shows variability with a period of 18.32 ± 0.30 h (valid for the middle moment of our run, UT 2010 Nov 5.0835), which we attribute to the nucleus rotation. This result is fully consistent with independent determinations around the same time by other teams. The pattern of repeatability is, however, imperfect, which is understendable given the suggested excitation of the rotation state, and the variability detected in CN correlates well with the cyclic changes in HCN, but only in the active phases. The identified coma structures, along with the snapshot of the nucleus orientation obtained by EPOXI, enable us to estimate the spin axis orientation. We obtain RA = 122 • , Dec = +16 • (epoch J2000.0), neglecting at this point the rotational excitation.

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Stardust-NExT, Deep Impact, and the accelerating spin of 9P/Tempel 1

Cited by 48 publications

References 42 publications

The changing rotation period of comet 67P/Churyumov-Gerasimenko controlled by its activity

The changing rotation period of comet 67P/Churyumov-Gerasimenko controlled by its activity

The rotation state of 67P/Churyumov-Gerasimenko from approach observations with the OSIRIS cameras on Rosetta

Rotation-stimulated structures in the CN and C₃comae of comet 103P/Hartley 2 close to the EPOXI encounter

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Stardust-NExT, Deep Impact, and the accelerating spin of 9P/Tempel 1

Cited by 48 publications

References 42 publications

The changing rotation period of comet 67P/Churyumov-Gerasimenko controlled by its activity

The changing rotation period of comet 67P/Churyumov-Gerasimenko controlled by its activity

The rotation state of 67P/Churyumov-Gerasimenko from approach observations with the OSIRIS cameras on Rosetta

Rotation-stimulated structures in the CN and C3comae of comet 103P/Hartley 2 close to the EPOXI encounter

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Rotation-stimulated structures in the CN and C₃comae of comet 103P/Hartley 2 close to the EPOXI encounter