Simultaneous spectroscopic and photometric observations of binary asteroids

Polishook, David; Brosch, Noah; Prialnik, Dina; Kaspi, S.

doi:10.1111/j.1945-5100.2009.tb02005.x

Cited by 8 publications

(7 citation statements)

References 25 publications

(50 reference statements)

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“…This implies that the two components are spectraly identical from 0.95 to 1.65 µm, within the precision of our measurements. Such a similarity between the components of multiple systems have already been reported for several other main-belt asteroids: (22) Kalliope (Laver et al, 2009), (90) Antiope (Polishook et al, 2009;Marchis et al, 2011), (130) Elektra (Yang et al, 2016), and (379) Huenna (DeMeo et al, 2011).…”

Section: Spectrum Of S1supporting

confidence: 76%

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: Spectrum Of S1supporting

confidence: 76%

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

Pajuelo

Carry

Vachier

et al. 2018

Icarus

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“…Combined with our determination of a diameter of 187 ± 21.5 km, we derive a diameter of 2.4 +1.8 −1.1 km for the satellite, under the assumption of a similar albedo for both. This assumption is supported by the multiple reports of spectral similarities between the components of multiple asteroid systems: (22) Kalliope (Laver et al, 2009), ( 90) Antiope (Polishook et al, 2009), ( 107) Camilla (Pajuelo et al, 2018), ( 130) Elektra (Yang et al, 2016), and (379) Huenna (DeMeo et al, 2011).…”

Section: Spectrum and Diameter Of The Satellitementioning

confidence: 75%

Homogeneous internal structure of CM-like asteroid (41) Daphne

Carry

Vachier

Berthier

et al. 2019

A&A

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Context. CM-like asteroids (Ch and Cgh classes) are a major population within the broader C-complex, encompassing about 10% of the mass of the main asteroid belt. Their internal structure has been predicted to be homogeneous, based on their compositional similarity as inferred from spectroscopy (Vernazza et al., 2016, AJ 152, 154) and numerical modeling of their early thermal evolution (Bland & Travis, 2017, Sci. Adv. 3, e1602514). Aims. Here we aim to test this hypothesis by deriving the density of the CM-like asteroid (41) Daphne from detailed modeling of its shape and the orbit of its small satellite. Methods. We observed Daphne and its satellite within our imaging survey with the Very Large Telescope extreme adaptive-optics SPHERE/ZIMPOL camera (ID 199.C-0074, PI P. Vernazza) and complemented this data set with earlier Keck/NIRC2 and VLT/NACO observations. We analyzed the dynamics of the satellite with our Genoid meta-heuristic algorithm. Combining our high-angular resolution images with optical lightcurves and stellar occultations, we determine the spin period, orientation, and 3-D shape, using our ADAM shape modeling algorithm. Results. The satellite orbits Daphne on an equatorial, quasi-circular, prograde orbit, like the satellites of many other large main-belt asteroids. The shape model of Daphne reveals several large flat areas that could be large impact craters. The mass determined from this orbit combined with the volume computed from the shape model implies a density for Daphne of 1.77 ±0.26 g·cm −3 (3 σ). This density is consistent with a primordial CM-like homogeneous internal structure with some level of macroporosity (≈17%). Conclusions. Based on our analysis of the density of Daphne and 75 other Ch/Cgh-type asteroids gathered from the literature, we conclude that the primordial internal structure of the CM parent bodies was homogeneous.

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“…The components' spectra are remarkably similar between 1.1. and 2.4 µm (identical within a 7% margin) and do not show any absorption features that could be due to the presence of mafic minerals, ices, or organics on the surface. Polishook et al (2009) recently reported a visible-wavelength spectroscopic study of the system in a mutual event configuration, which similarly detected no variations of reflectance in their wavelength range. The addition of the near-infrared range, which includes absorption bands of materials detected on the surface of asteroids and shows a larger gradient of slopes among the C-group asteroid population (Fig.…”

Section: Discussionmentioning

confidence: 95%

“…From the VOBAD database (Marchis et al 2006), we estimate that such a study could be performed on up to 70 binary asteroids whose components have a size ratio of 1/5 or higher, the typical limit of detection by photometric surveys (Pravec et al 2006). Polishook et al (2009) showed that, in the case of (90) Antiope, such photometric and spectroscopic studies could be conducted using 1m-class telescopes. We recommend pursuing such studies in the future, broadening them to longer wavelengths in near-and mid-infrared.…”

Section: Discussionmentioning

confidence: 99%

“…The Themis family members could have been formed from an already differentiated body. Polishook et al (2009) conducted an extensive visible photometric and spectroscopic study of (90) Antiope in January 2008 while the system was seen nearly edge-on from Earth, presenting total eclipse configurations. All spectra taken before and after two eclipses separated by 1.5 rotations are featureless and their spectral slopes are stable within 3%.…”

Section: [Insert Fig 1]mentioning

confidence: 99%

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The origin of (90) Antiope from component-resolved near-infrared spectroscopy

Marchis

Enriquez

Emery

et al. 2011

Icarus

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Abstract:The origin of the similary-sized binary asteroid (90) Antiope remains an unsolved puzzle. To constrain the origin of this unique double system, we recorded individual spectra of the components using SPIFFI, a near-infrared integral field spectrograph fed by SINFONI, an adaptive optics module available on VLT-UT4. Using our previously published orbital model, we requested telescope time when the separation of the components of (90) Antiope was larger than 0.087", to minimize the contamination between components, during the February 2009 opposition. Several multi-spectral datacubes in J band (SNR=40) and H+K band (SNR=100) were recorded in three epochs and revealed the two components of (90) Antiope. After developing a specific photometric extraction method and running an error analysis by Monte-Carlo simulations, we successfully extracted reliable spectra of both components from 1.1 to 2.4 µm taken on the night of February 21, 2009. These spectra do not display any significant absorption features due to mafic mineral, ices, or organics, and their slopes are in agreement with both components being C-or Cb-type asteroids. Their constant flux ratio indicates that both components' surface reflectances are quite similar, with a 1-sigma variation of 7%.By comparison with 2MASS J, H, K color distribution of observed Themis family members, we conclude that both bodies were most likely formed at the same time and from the same material. The similarly-sized system could indeed be the result of the breakup of a rubble-pile proto-Antiope into two equal-sized bodies, but other scenarios of formation implying a common origin should also be considered.

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Simultaneous spectroscopic and photometric observations of binary asteroids

Cited by 8 publications

References 25 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

Homogeneous internal structure of CM-like asteroid (41) Daphne

The origin of (90) Antiope from component-resolved near-infrared spectroscopy

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