Impact origin of the Vesta family

Asphaug, Erik

doi:10.1111/j.1945-5100.1997.tb01584.x

Cited by 114 publications

(90 citation statements)

References 51 publications

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“…Diogenites material originated from a plutonic layer deep in Vesta's lower crust/upper mantle (McSween et al 2010) and it has been suggested that the lack of this mineralogy among the V-type asteroids could be due to the difficulty in excavating large fragments from depths (Moskovitz et al 2010;Burbine et al 2009). However, numerical simulations (Asphaug 1997) of the South Pole crater formation have shown that a large fraction of the excavated material would have come from Vesta's mantle and not its crust, because it has a diogenite-dominated composition. Thus, the identification of several diogenitic asteroids can help constraining the excavation mechanism.…”

Section: Resultsmentioning

confidence: 99%

“…The HEDs are basaltic meteorites and are thought to come from large asteroids that melted to form a metallic core and basaltic magmas after the formation. A close connection between asteroid (4) Vesta and these basaltic achondrites was established during the earliest studies, including visible and infrared spectroscopic investigations (McCoord et al 1970;McFadden et al 1977;Xu et al 1995;Burbine et al 2001), numerical and dynamical simulations (Asphaug 1997), and spatial resolved observations ; Thomas et al 1997). However, recent studies in oxygen isotopic composition from a common mass-fractionation line suggest that a few eucrite-like A&A 533, A77 (2011) meteorites come from other bodies, or that (4) Vesta was not completely homogenized during differentiation (McSween et al 2010).…”

Section: Introductionmentioning

confidence: 99%

“…According to hydrocode simulation, Asphaug (1997) found that multikilometer fragments can be ejected from (4) Vesta with speeds up to ΔV = 550 m/s. From Gauss equations these ΔV values would lead to orbital changes up to ≈0.15 AU, ≈0.03 and ≈1 • in semi-major axis, eccentricity, e, and inclination, i, respectively .…”

Section: Introductionmentioning

confidence: 99%

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Spectral and mineralogical characterization of inner main-belt V-type asteroids

Sanctis

Migliorini

Jasmin

et al. 2011

A&A

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Context. V-type asteroids in the inner main belt are thought to be genetically related to (4) Vesta as collisional fragments. We investigate their relationship with Vesta observing putative V-type asteroids. Aims. The aim of this work is to observe candidate V-type asteroids, selected in different regions of the inner main belt, to characterize them and hence better understand their relationship with (4) Vesta. Methods. We present new NIR reflectance spectra of 18 V-type candidate asteroids, selected from datasets of possible V-type asteroids. The data were obtained at the 3.6 m Telescopio Nazionale Galileo, covering the spectral range 0.7 to 2.5 μm. We derive spectral parameters from NIR spectra to infer mineralogical information of the observed asteroids. The spectra of these asteroids are examined and compared to those of Howardite-Eucrite-Diogenite meteorites (HED), of which (4) Vesta is believed to be the parent body, and other V-type asteroids observed during previous campaigns. To enlarge the data set and increase the statistical significance of the analysis, we included the data presented in our previous article, obtaining a final data set of 41 V-type asteroids. Results. The V-type asteroids examined here show a higher variability of band parameters with respect to HEDs values, as for (4) Vesta. This result indicates that (4) Vesta and V-type asteroids have mineralogies that are not completely represented in the HEDs collection.Conclusions. An important finding is that some of the observed asteroids show spectral characteristics similar to diogenites, a result that may have relevant implications on their origin. Moreover, most of the diogenitic asteroids are not members of the Vesta classical family.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spectral and mineralogical characterization of inner main-belt V-type asteroids

Sanctis

Migliorini

Jasmin

et al. 2011

A&A

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“…A large impact crater of 460 km diameter, 13 km depth with a large central peak, has been identified on Vesta (Thomas et al, 1997) which may have extended beyond the crust into the mantle layer and ejected many Vestoids and HEDs (McSween et al, 2010). The age of this impact crater is controversial, with some evidence suggesting it occurred during the Late Heavy Bombardment period of 3.5-4.0 billion years ago (Scott et al, 2009b), and other evidence supporting an age of only 1 billion years (Asphaug, 1997). Ejecta from this large impact, possibly including samples of the deep asteroidal crust and mantle, may now be present on the surface of 4-Vesta.…”

Section: Introductionmentioning

confidence: 99%

Zinc isotopes in HEDs: Clues to the formation of 4-Vesta, and the unique composition of Pecora Escarpment 82502

Paniello¹,

Moynier²,

Beck

et al. 2012

Geochimica et Cosmochimica Acta

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The d 66 Zn (permil deviation of the 66 Zn/ 64 Zn ratio from a terrestrial standard) values for a suite of 20 non-Antarctic HED (howardite-eucrite-diogenite) meteorites and one mesosiderite, and for eight Antarctic eucrites and diogenites, were measured in order to determine the role of volatization in the formation of their presumed parent body, the asteroid 4-Vesta. The 20 non-Antarctic HEDs had d 66 Zn values that ranged from À2.0& to +1.67&, with a mean value of À0.01 ± 0.39& (2 se); this range likely represents a small-scale heterogeneity due to brecciation induced by multiple impacts. The non-Antarctic eucrites (d 66 Zn = +0.00 ± 0.58& (2 se), n = 12) were isotopically the same as the diogenites (d 66 Zn = À0.31 ± 0.80& (2 se), n = 4), and the howardites (d 66 Zn = +0.26 ± 0.37& (2 se), n = 4). On average, non-Antarctic eucrite falls were isotopically heavier (+0.50&) than non-Antarctic finds (À1.00&). The Antarctic finds studied were all unbrecciated samples, and they were significantly heavier than the non-Antarctic samples with a d 66 Zn range of +1.63& to +6.22& for four eucrites (mean, +4.32&) and +0.94& to +1.60& for three diogenites (mean + 1.23&), excluding one anomalous sample, while their Zn concentration is significantly lower than the brecciated samples. These data suggest that the unbrecciated eucrites probably represent the eucritic crust shortly after differentiation and cooling of the parent asteroid, at which time volatization of lighter zinc isotopes led to an isotopically heavy crust. Early impact events caused the ejection of these unbrecciated meteorites, which were subsequently spared from brecciation caused by multiple additional impacts on the much larger Vesta. The range of d 66 Zn values and Zn concentration for the brecciated HEDs in this study supports a major contribution to the Vestan surface by chondritic impactors (À1.30 < d 66 Zn < +0.76& for ordinary and carbonaceous chondrites). The anomalous eucrite PCA 82502 (d 66 Zn = À7.75&) is significantly isotopically lighter than the other HEDs and is the natural sample with the lightest Zn isotopic composition reported in the solar system to date. This meteorite most likely originated from a distinct parent body.

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“…Diskresolved Hubble space telescope (HST) observations have been used to estimate its shape (Thomas et al 1997), giving an equivalent radius of about 258 ± 5 km. A huge crater located at the South pole was identified by Thomas et al (1997), which was suggested to be most likely due to to an impact with a 35 km projectile (Asphaug 1997) occurred in the past. Vesta is large enough to be a differentiated body.…”

Section: Introductionmentioning

confidence: 99%

Thermal properties of (4) Vesta derived fromHerschelmeasurements

Leyrat

Barucci

Mueller³

et al. 2012

A&A

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Aims. We report in this paper the results provided by new infrared observations of the asteroid (4) Vesta obtained between April 2010 and June 2010 with the Herschel space observatory (ESA) in the wavelength range 70-500 μm when the asteroid was seen from the Northern hemisphere. Over this period, the thermal flux of Vesta was observed at different rotational phases and a large fraction of the surface was visible. Methods. A thermophysical model was used to derive thermal properties such as infrared emissivity, thermal inertia and surface roughness. Results. We found an average thermal inertia Γ = 20 +20 −10 J m −2 K −1 s −1/2 . The surface roughness on the Northern hemisphere, while poorly constrained, appears to be low on Vesta with a mean slope angleθ ∼ 23 • . Surface temperatures range from 40 K to 248 K. We cannot confirm any longitudinal variation of the thermal flux as it remains within the error bars. More observations are needed to confirm if the eastern hemisphere could have either a slightly higher thermal inertia suggesting a rockier surface or a smooth surface with a higher beaming factor. We emphasize an important decrease of the infrared emissivity of Vesta with the wavelength, ranging from 0.9 at 70 μm to 0.70 at 500 μm.

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Impact origin of the Vesta family

Cited by 114 publications

References 51 publications

Spectral and mineralogical characterization of inner main-belt V-type asteroids

Spectral and mineralogical characterization of inner main-belt V-type asteroids

Zinc isotopes in HEDs: Clues to the formation of 4-Vesta, and the unique composition of Pecora Escarpment 82502

Thermal properties of (4) Vesta derived fromHerschelmeasurements

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