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

Carry, B.; Vachier, F.; Berthier, J.; Marsset, Michaël; Vernazza, Pierre; Grice, J.; Merline, W. J.; Lagadec, E.; Fienga, A.; Conrad, Al; Podlewska-Gaca, E.; Santana-Ros, T.; Viikinkoski, Matti; Hanuš, Josef; Dumas, Christophe; Drummond, Jack D.; Tamblyn, Peter; Chapman, C. R.; Behrend, R.; Bernasconi, L.; Bartczak, P.; Benkhaldoun, Z.; Birlan, Mirel; Castillo‐Rogez, Julie; Cipriani, F.; Colas, François; Drouard, A.; Ďurech, Josef; Enke, B. L.; Fauvaud, S.; Ferrais, Marin; Fétick, Romain; Fusco, Thierry; Gillon, M.; Jehin, Emmanuël; Jordá, L.; Kaasalainen, M.; Keppler, M.; Kryszczyńska, A.; Lamy, Philippe; Marchis, Franck; Marciniak, A.; Michałowski, Tadeusz; Michel, P.; Pajuelo, M.; Tanga, P.; Vigan, A.; Warner, Brian D.; Witasse, Olivier; Yang, Bin; Zurlo, A.

doi:10.1051/0004-6361/201833898

Cited by 28 publications

(12 citation statements)

References 112 publications

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“…In this interpretation, some bodies accreted early enough to have experienced at least partial dehydration (Weiss & Elkins-Tanton 2013). The latter case is not supported by current measurements of the spectral properties and densities of D>150 km CM-like bodies (Carry 2012;Vernazza et al 2016;Carry et al 2019), whose low values are more compatible with a mostly or fully homogenous interior.…”

Section: Discussionmentioning

confidence: 59%

IDP-like Asteroids Formed Later than 5 Myr After Ca–Al-rich Inclusions

Neveu

Vernazza

2019

ApJ

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The parent bodies of ordinary chondrites, carbonaceous CM chondrites, and interplanetary dust particles (IDPs) represent most of the mass of the solar system's small (D250km) bodies. The times of formation of the ordinary and carbonaceous CM chondrite parent bodies have previously been pinpointed, respectively, to ≈2 and 3-4 million years after calcium-aluminum-rich inclusions (CAIs). However, the timing of the formation of IDP parent bodies such as P-and D-type main-belt asteroids and Jupiter Trojans has not been tightly constrained. Here, we show that they formed later than 5-6 million years after CAIs. We use models of their thermal and structural evolution to show that their anhydrous surface composition would otherwise have been lost due to melting and icerock differentiation driven by heating from the short-lived radionuclide 26 Al. This suggests that IDP-like volatilerich small bodies may have formed after the gas of the protoplanetary disk dissipated and thus later than the massive cores of the giant planets. It also confirms an intuitive increase in formation times with increased heliocentric distance, and suggests that there may have been a gap in time between the formation of carbonaceous chondrite (chondrule-rich) and IDP (chondrule-poor) parent bodies.

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Section: Discussionmentioning

confidence: 59%

IDP-like Asteroids Formed Later than 5 Myr After Ca–Al-rich Inclusions

Neveu

Vernazza

2019

ApJ

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“…For instance, the bulk density is compatible within 1 σ error with those of the two largest C-type asteroids, Ceres (2.161±0.003 g · cm −3 , Park et al 2019) and Hygiea (1.94±0.25 g · cm −3 , Vernazza et al 2019), but also of silicate bodies such as (25143) Itokawa (1.90±0.13 g · cm −3 , Fujiwara et al 2006) or (433) Eros (2.67±0.10 g · cm −3 , Veverka et al 2000). Current estimates of the densities of asteroids with masses greater than ∼5 × 10 18 kg imply a small amount of macroporosity within these bodies (Carry 2012;Viikinkoski et al 2015b;Marsset et al 2017;Carry et al 2019;Hanuš et al 2019), and spectroscopic observations of Interamnia in the 3micron region have revealed the presence of hydrated material at its surface (Usui et al 2019) and spectral similarity to Ceres (Rivkin et al 2019). Therefore, we can assume that Interamnia's bulk density is close to that of Ceres.…”

Section: Densitymentioning

confidence: 84%

“…Investigating these questions is one of the main motivations of our European Southern Observatory (ESO) large program (id: 199.C-0074; of which the aim is to constrain the shape of the forty largest main-belt asteroids. So far, our program has revealed that (10) Hygiea, the fourth largest main-belt asteroid (D∼434 km) possesses a shape that is nearly as spherical as that of (1) Ceres , while being twice as small, whereas D ∼100-200 km bodies [(89) Julia, (16) Psyche, (41) Daphne] possess irregular shapes Viikinkoski et al 2018;Carry et al 2019). Asteroid (7) Iris (D∼214 km) is an intermediate case, as its shape appears to be consistent with that of an oblate spheroid with a large equatorial excavation (Hanuš et al 2019).…”

Section: Introductionmentioning

confidence: 99%

(704) Interamnia: a transitional object between a dwarf planet and a typical irregular-shaped minor body

Hanuš

Vernazza

Viikinkoski

et al. 2020

A&A

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Context. With an estimated diameter in the 320 to 350 km range, (704) Interamnia is the fifth largest main belt asteroid and one of the few bodies that fills the gap in size between the four largest bodies with D > 400 km (Ceres, Vesta, Pallas and Hygiea) and the numerous smaller bodies with diameter ≤200 km. However, despite its large size, little is known about the shape and spin state of Interamnia and, therefore, about its bulk composition and past collisional evolution. Aims. We aimed to test at what size and mass the shape of a small body departs from a nearly ellipsoidal equilibrium shape (as observed in the case of the four largest asteroids) to an irregular shape as routinely observed in the case of smaller (D ≤200 km) bodies. Methods. We observed Interamnia as part of our ESO VLT/SPHERE large program (ID: 199.C-0074) at thirteen different epochs. In addition, several new optical lightcurves were recorded. These data, along with stellar occultation data from the literature, were fed to the All-Data Asteroid Modeling (ADAM) algorithm to reconstruct the 3D-shape model of Interamnia and to determine its spin state. Results. Interamnia's volume-equivalent diameter of 332 ± 6 km implies a bulk density of ρ=1.98 ± 0.68 g · cm −3 , which suggests that Interamnia -like Ceres and Hygiea -contains a high fraction of water ice, consistent with the paucity of apparent craters. Our observations reveal a shape that can be well approximated by an ellipsoid, and that is compatible with a fluid hydrostatic equilibrium at the 2 σ level. Conclusions. The rather regular shape of Interamnia implies that the size/mass limit, under which the shapes of minor bodies with a high amount of water ice in the subsurface become irregular, has to be searched among smaller (D ≤300km) less massive (m ≤3x10 19 kg) bodies.

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“…On the other hand, the hydrated Ch/Cgh-type asteroids (that do not contain the 1-μm band) are partly linked with CM chondrites (Rivkin, 2012;Bland and Travis, 2017;Vernazza et al, 2017;Carry et al, 2019). Hiroi et al (1993) also suggested a link with the CI/CM meteorites.…”

Section: Discussionmentioning

confidence: 99%

Predicting Asteroid Types: Importance of Individual and Combined Features

Klimczak

Kotłowski

Oszkiewicz

et al. 2021

Front. Astron. Space Sci.

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Asteroid taxonomies provide a link to surface composition and mineralogy of those objects, although that connection is not fully unique. Currently, one of the most commonly used asteroid taxonomies is that of Bus-DeMeo. The spectral range covering 0.45–2.45 μm is used to assign a taxonomic class in that scheme. Such observations are only available for a few hundreds of asteroids (out of over one million). On the other hand, a growing amount of space and ground-based surveys delivers multi-filter photometry, which is often used in predicting asteroid types. Those surveys are typically dedicated to studying other astronomical objects, and thus not optimized for asteroid taxonomic classifications. The goal of this study was to quantify the importance and performance of different asteroid spectral features, parameterizations, and methods in predicting the asteroid types. Furthermore, we aimed to identify the key spectral features that can be used to optimize future surveys toward asteroid characterization. Those broad surveys typically are restricted to a few bands; therefore, selecting those that best link them to asteroid taxonomy is crucial in light of maximizing the science output for solar system studies. First, we verified that with the increased number of asteroid spectra, the Bus–DeMeo procedure to create taxonomy still produces the same overall scheme. Second, we confirmed that machine learning methods such as naive Bayes, support vector machine (SVM), gradient boosting, and multilayer networks can reproduce that taxonomic classification at a high rate of over 81% balanced accuracy for types and 93% for complexes. We found that multilayer perceptron with three layers of 32 neurons and stochastic gradient descent solver, batch size of 32, and adaptive learning performed the best in the classification task. Furthermore, the top five features (spectral slope and reflectance at 1.05, 0.9, 0.65, and 1.1 μm) are enough to obtain a balanced accuracy of 93% for the prediction of complexes and six features (spectral slope and reflectance at 1.4, 1.05, 0.9, 0.95, and 0.65 μm) to obtain 81% balanced accuracy for taxonomic types. Thus, to optimize future surveys toward asteroid classification, we recommend using filters that cover those features.

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

Cited by 28 publications

References 112 publications

IDP-like Asteroids Formed Later than 5 Myr After Ca–Al-rich Inclusions

IDP-like Asteroids Formed Later than 5 Myr After Ca–Al-rich Inclusions

(704) Interamnia: a transitional object between a dwarf planet and a typical irregular-shaped minor body

Predicting Asteroid Types: Importance of Individual and Combined Features

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