Physical and dynamical properties of the main belt triple Asteroid (87) Sylvia

Berthier, J.; Vachier, F.; Marchis, Franck; Ďurech, Josef; Carry, B.

doi:10.1016/j.icarus.2014.05.046

Cited by 39 publications

(47 citation statements)

References 53 publications

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“…Although a circular orbit, co-planar with S1 is marginally within the range of uncertainty, such a solution results in significantly higher residuals. This configuration of an outer satellite on a circular and equatorial orbit with an inner satellite on an inclined and more eccentric orbit has already been reported for other triple systems: (45) Eugenia, (87) Sylvia, and (130) Elektra Fang et al, 2012;Berthier et al, 2014;Yang et al, 2016;Drummond et al, 2016). Table 1: Orbital elements of the satellites of Camilla, S1 and S2, expressed in EQJ2000, obtained with Genoid: orbital period P, semi-major axis a, eccentricity e, inclination i, longitude of the ascending node Ω, argument of pericenter ω, time of pericenter t p .…”

Section: Orbit Of S2: S/2016 (107)supporting

confidence: 81%

“…The reliability of Genoid has been assessed during a stellar occultation by (87) Sylvia and its satellites Romulus and Remus on January 6, 2013: Genoid had been used to predict the position of Romulus before the event, directing observers to locations specifically to target the satellite. Four different observers detected an occultation by Romulus at only 13.5 km off the predicted track (the cross-track uncertainty was 65 km, Berthier et al, 2014).…”

Section: Orbit Determination With Genoidmentioning

confidence: 99%

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Physical, spectral, and dynamical properties of asteroid (107) Camilla and its satellites

Pajuelo

Carry

Vachier

et al. 2018

Icarus

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The population of large 100+ km asteroids is thought to be primordial. As such, they are the most direct witnesses of the early history of our Solar System available. Those among them with satellites allow study of the mass, and hence density and internal structure. We study here the dynamical, physical, and spectral properties of the triple asteroid (107) Camilla from lightcurves, stellar occultations, optical spectroscopy, and high-contrast and high-angular-resolution images and spectro-images.Using 80 positions measured over 15 years, we determine the orbit of its larger satellite, S/2001 (107) 1, to be circular, equatorial, and prograde, with root-mean-square residuals of 7.8 mas, corresponding to a sub-pixel accuracy. From 11 positions spread over three epochs only, in 2015 and 2016, we determine a preliminary orbit for the second satellite S/2016 (107) 1. We find the orbit to be somewhat eccentric and slightly inclined to the primary's equatorial plane, reminiscent of the properties of inner satellites of other asteroid triple systems. Comparison of the near-infrared spectrum of the larger satellite reveals no significant difference with Camilla. Hence, both dynamical and surface properties argue for a formation of the satellites by excavation from impact and re-accumulation of ejecta in orbit.We determine the spin and 3-D shape of Camilla. The model fits well each data set: lightcurves, adaptive-optics images, and stellar occultations. We determine Camilla to be larger than reported from modeling of mid-infrared photometry, with a sphericalvolume-equivalent diameter of 254 ± 36 km (3 σ uncertainty), in agreement with recent results from shape modeling (Hanus et al., 2017, A&A 601). Combining the mass of (1.12 ± 0.01) × 10 19 kg (3 σ uncertainty) determined from the dynamics of the satellites and the volume from the 3-D shape model, we determine a density of 1,280 ± 130 kg·m −3 (3 σ uncertainty). From this density, and considering Camilla's spectral similarities with (24) Themis and (65) Cybele (for which water ice coating on surface grains was reported), we infer a silicate-to-ice mass ratio of 1-6, with a 10-30% macroporosity.

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Section: Orbit Of S2: S/2016 (107)supporting

confidence: 81%

Section: Orbit Determination With Genoidmentioning

confidence: 99%

Physical, spectral, and dynamical properties of asteroid (107) Camilla and its satellites

Pajuelo

Carry

Vachier

et al. 2018

Icarus

Self Cite

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show abstract

“…Many images were already used independently in previous shape studies (Marchis et al 2006;Drummond et al 2009;Descamps et al 2009;Merline et al 2013;Hanuš et al 2013b;Berthier et al 2014). In Tab.…”

Section: Keck Disk-resolved Datamentioning

confidence: 99%

“…Such approach is sensitive to the boundary condition applied when extracting the contour. Shape models of asteroids (22) Kalliope, (87) Sylvia, (93) Minerva, and (216) Kleopatra have been previously derived (Descamps et al 2008;Berthier et al 2014;Marchis et al 2013;Kaasalainen & Viikinkoski 2012). As the first step, we decided to validate our modeling approach on these asteroids -we have similar or even larger optical, disk-resolved and stellar occultation datasets for them.…”

Section: Comparison With Previously Modeled Primariesmentioning

confidence: 99%

Volumes and bulk densities of forty asteroids from ADAM shape modeling

Hanuš

Viikinkoski

Marchis

et al. 2017

A&A

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Context. Disk-integrated photometric data of asteroids do not contain accurate information on shape details or size scale. Additional data such as disk-resolved images or stellar occultation measurements further constrain asteroid shapes and allow size estimates. Aims. We aim to use all available disk-resolved images of about forty asteroids obtained by the Near-InfraRed Camera (Nirc2) mounted on the W.M. Keck II telescope together with the disk-integrated photometry and stellar occultation measurements to determine their volumes. We can then use the volume, in combination with the known mass, to derive the bulk density. Methods. We download and process all asteroid disk-resolved images obtained by the Nirc2 that are available in the Keck Observatory Archive (KOA). We combine optical disk-integrated data and stellar occultation profiles with the disk-resolved images and use the All-Data Asteroid Modeling (ADAM) algorithm for the shape and size modeling. Our approach provides constraints on the expected uncertainty in the volume and size as well.Results. We present shape models and volume for 41 asteroids. For 35 asteroids, the knowledge of their mass estimates from the literature allowed us to derive their bulk densities. We clearly see a trend of lower bulk densities for primitive objects (C-complex) than for S-complex asteroids. The range of densities in the X-complex is large, suggesting various compositions. Moreover, we identified a few objects with rather peculiar bulk densities, which is likely a hint of their poor mass estimates. Asteroid masses determined from the Gaia astrometric observations should further refine most of the density estimates.

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“…The latter results in model that explains different datasets simultaneously rather than being simply scaled, which is a great advantage of multi-dataset inversion. Although limited to a small number of targets, it provides valuable and detailed information about them (Carry et al 2008;Berthier et al 2014;Pajuelo et al 2018;Vernazza et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Volume uncertainty assessment method of asteroid models from disc-integrated visual photometry

Bartczak

Dudziński

2019

Monthly Notices of the Royal Astronomical Society

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The need for more accurate asteroid models is perhaps secondary to the need to measure their quality. The uncertainties of models' parameters propagate to quantities like volume or density -the most important and informative properties of asteroidsaffecting conclusions about their physical nature. Our knowledge on shapes and spins of small solar system bodies comes mostly from visual, disk-integrated photometry. In this work we present a method for asteroid model uncertainty assessment based on visual photometry (lightcurves and sparse-in-time absolute measurements) allowing the determination of realistic volume uncertainty, as well as spin axis orientation, rotational period and local surface features. The sensitivity analysis is conducted by creating clones of the nominal model and accepting the ones that fit the observations within a confidence level. The uncertainties of model parameters are extracted from the extreme values found in the accepted clone population. Creation of such population of clones enables the conversion of a deterministic asteroid model into stochastic one, and can be utilized to create observation predictions with error bars. The method was used to assess the uncertainties of fictitious test models and real targets, i.e. (21) Lutetia, (89) Julia, (243) Ida, (433) Eros and (162173) Ryugu. We conclude that volumes, and subsequently, densities of asteroids derived from lightcurve-based models likely have vastly understated uncertainties, the biggest source of which is the inability to establish the extent of the model along its spin axis.

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Physical and dynamical properties of the main belt triple Asteroid (87) Sylvia

Cited by 39 publications

References 53 publications

Physical, spectral, and dynamical properties of asteroid (107) Camilla and its satellites

Physical, spectral, and dynamical properties of asteroid (107) Camilla and its satellites

Volumes and bulk densities of forty asteroids from ADAM shape modeling

Volume uncertainty assessment method of asteroid models from disc-integrated visual photometry

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