Photometric and spectroscopic evidence for a dense ring system around Centaur Chariklo

Duffárd, R.; Pinilla-Alonso, N.; Ortiz, J. L.; Álvarez-Candal, A.; Sicardy, B.; Santos-Sanz, P.; Morales, N.; Colazo, C.; Fernández-Valenzuela, E.; Braga-Ribas, F.

doi:10.1051/0004-6361/201424208

Cited by 46 publications

(80 citation statements)

References 35 publications

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“…Thus, our results provide another (quantitative) proof that the particle size distribution of Saturn's rings is not primordial. The same size distributions are expected for other collision-dominated rings, such as the rings of Uranus (42,43), Chariklo (44,45), and Chiron (46,47) and possibly around extrasolar objects (48)(49)(50).…”

Section: Discussionsupporting

confidence: 67%

Size distribution of particles in Saturn’s rings from aggregation and fragmentation

Brilliantov

Krapivsky

Bodrova

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

129

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Saturn's rings consist of a huge number of water ice particles, with a tiny addition of rocky material. They form a flat disk, as the result of an interplay of angular momentum conservation and the steady loss of energy in dissipative interparticle collisions. For particles in the size range from a few centimeters to a few meters, a power-law distribution of radii, ∼ r −q with q ≈ 3, has been inferred; for larger sizes, the distribution has a steep cutoff. It has been suggested that this size distribution may arise from a balance between aggregation and fragmentation of ring particles, yet neither the power-law dependence nor the upper size cutoff have been established on theoretical grounds. Here we propose a model for the particle size distribution that quantitatively explains the observations. In accordance with data, our model predicts the exponent q to be constrained to the interval 2.75 ≤ q ≤ 3.5. Also an exponential cutoff for larger particle sizes establishes naturally with the cutoff radius being set by the relative frequency of aggregating and disruptive collisions. This cutoff is much smaller than the typical scale of microstructures seen in Saturn's rings. (1-3) and the observation of rapid processes in the ring system (4) indicate that the shape of the particle size distribution is likely not primordial or a direct result of the ring-creating event. Rather, ring particles are believed to be involved in active accretion-destruction dynamics (5-13) and their sizes vary over a few orders of magnitude as a power law (14-17), with a sharp cutoff for large sizes (18-21). Moreover, tidal forces fail to explain the abrupt decay of the size distribution for house-sized particles (22). One wishes to understand the following: (i) Can the interplay between aggregation and fragmentation lead to the observed size distribution? And (ii) is this distribution peculiar for Saturn's rings, or is it universal for planetary rings in general? To answer these questions quantitatively, one needs to elaborate a detailed model of the kinetic processes in which the ring particles are involved. Here we develop a theory that quantitatively explains the observed properties of the particle size distribution and show that these properties are generic for a steady state, when a balance between aggregation and fragmentation holds. Our model is based on the hypothesis that collisions are binary and that they may be classified as aggregative, restitutive, or disruptive (including collisions with erosion); which type of collision is realized depends on the relative speed of colliding particles and their masses. We apply the kinetic theory of granular gases (23, 24) for the multicomponent system of ring particles to quantify the collision rate and the type of collision. Results and DiscussionModel. Ring particles may be treated as aggregates built up of primary grains (9) of a certain size r 1 and mass m 1 . [Observations indicate that particles below a certain radius are absent in dense rings (16).] Denote by m k = km 1 the mass of rin...

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Section: Discussionsupporting

confidence: 67%

Size distribution of particles in Saturn’s rings from aggregation and fragmentation

Brilliantov

Krapivsky

Bodrova

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

129

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“…3), 7.24±0.08 mag, is compatible with this value. Consistently with results in Fornasier et al (2014) and Duffard et al (2014) no coma was detected (but see Sect. 8 for additional details).…”

Section: Chariklo (1997 Cu 26 )supporting

confidence: 91%

“…The amplitude in Lacerda & Luu (2006) is about 0.1 mag. The rings affect the amplitude of the overall rotational light-curve as their aspect angle changes over time (Duffard et al 2014). The value of the absolute magnitude in V found by Fornasier et al (2014) is 7.03±0.10 mag; our determination (found as described in Sect.…”

Section: Chariklo (1997 Cu 26 )supporting

confidence: 53%

“…Currently the largest confirmed Centaur, Chariklo has a rotational period of 7.00±0.04 h, an effective radius of 119±5 km (Fornasier et al 2014), and a dense ring system (Braga-Ribas et al 2014;Duffard et al 2014). Due to the rings, the average value of the albedo, 4.2% (Fornasier et al 2014), is variable (Duffard et al 2014 ′′ /minute and the typical exposure time was 400 s; therefore, the expected shift within a given image is again well within the seeing disk.…”

Section: Chariklo (1997 Cu 26 )mentioning

confidence: 99%

“…Due to the rings, the average value of the albedo, 4.2% (Fornasier et al 2014), is variable (Duffard et al 2014 ′′ /minute and the typical exposure time was 400 s; therefore, the expected shift within a given image is again well within the seeing disk. The average geocentric distance of Chariklo during the observing run was∆ = 12.98 AU, the average heliocentric distance wasr=13.20 AU, and the average phase angle (Earth-Chariklo-Sun angle) wasᾱ = 4.…”

Section: Chariklo (1997 Cu 26 )mentioning

confidence: 99%

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Photometry of Centaurs and trans-Neptunian objects: 2060 Chiron (1977 UB), 10199 Chariklo (1997 CU26), 38628 Huya (2000 EB173), 28978 Ixion (2001 KX76), and 90482 Orcus (2004 DW)

Galiazzo

Marcos²,

Marcos³

et al. 2016

Astrophys Space Sci

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Both Centaurs and trans-Neptunian objects (TNOs) are minor bodies found in the outer Solar System. Centaurs are a transient population that moves between the orbits of Jupiter and Neptune, and they probably diffused out of the TNOs. TNOs move mainly beyond Neptune. Some of these objects display episodic cometary behaviour; a few percent of them are known to host binary companions. Here, we study the lightcurves of two Centaurs -2060 Chiron (1977 periodogram analysis of the light-curves of these objects gives the following rotational periods: 5.5±0.4 h for Chiron, 7.0±0.6 h for Chariklo, 4.45±0.07 h for Huya, 12.4±0.3 h for Ixion, and 11.9±0.5 h for Orcus. The colour indices of Chiron are found to be B − V = 0.53 ± 0.05, V − R = 0.37 ± 0.08, and R − I = 0.36 ± 0.15. The values computed for Chariklo are V − R = 0.62 ± 0.07 and R − I = 0.61 ± 0.07. For Huya, we find V − R = 0.58 ± 0.09 and R − I = 0.64 ± 0.20. Our rotation periods are similar to and our colour values are consistent with those already published for these objects. We find very low levels of cometary activity (if any) and no sign of close or wide binary companions for these minor bodies.

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On the Evolution of Comets

Guilbert-Lepoutre¹,

Besse²,

Mousis³

et al. 2017

Comets as Tracers of Solar System Formation and Evolution

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Photometric and spectroscopic evidence for a dense ring system around Centaur Chariklo

Cited by 46 publications

References 35 publications

Size distribution of particles in Saturn’s rings from aggregation and fragmentation

Size distribution of particles in Saturn’s rings from aggregation and fragmentation

Photometry of Centaurs and trans-Neptunian objects: 2060 Chiron (1977 UB), 10199 Chariklo (1997 CU26), 38628 Huya (2000 EB173), 28978 Ixion (2001 KX76), and 90482 Orcus (2004 DW)

On the Evolution of Comets

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