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We present the discovery and extensive early-time observations of the Type Ic supernova (SN) PTF12gzk. Our light curves show a rise of 0.8mag within 2.5hr. Power-law fits (f(t) (t - t 0)n) to these data constrain the explosion date to within one day. We cannot rule out a quadratic fireball model, but higher values of n are possible as well for larger areas in the fit parameter space. Our bolometric light curve and a dense spectral sequence are used to estimate the physical parameters of the exploding star and of the explosion. We show that the photometric evolution of PTF12gzk is slower than that of most SNe Ic. The high ejecta expansion velocities we measure (∼30, 000kms-1 derived from line minima fourdays after explosion) are similar to the observed velocities of broad-lined SNe Ic associated with gamma-ray bursts (GRBs) rather than to normal SN Ic velocities. Yet, this SN does not show the persistent broad lines that are typical of broad-lined SNe Ic. The host-galaxy characteristics are also consistent with GRB-SN hosts, and not with normal SN Ic hosts. By comparison with the spectroscopically similar SN 2004aw, we suggest that the observed properties of PTF12gzk indicate an initial progenitor mass of 25-35M ⊙ and a large ((5-10) × 10 51erg) kinetic energy, the later being close to the regime of GRB-SN properties. © 2012. The American Astronomical Society. All rights reserved.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2010.03.002 Byline: Nicholas A. Moskovitz (a)(b), Mark Willman (a), Thomas H. Burbine (c), Richard P. Binzel (d), Schelte J. Bus (e) Keywords: Asteroids; Spectroscopy; Asteroids, Composition; Asteroid Vesta; Meteorites Abstract: V-type asteroids in the inner Main Belt (a Amongst these inner Main Belt asteroids we do not find evidence for non-Vestoid mineralogies. Instead, these asteroids seem to represent a continuum of compositions, consistent with an origin from a single differentiated parent body. In addition, our analysis shows that V-type asteroids with low inclinations (i Author Affiliation: (a) Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA (b) Carnegie Institution of Washington, Department of Terrestrial Magnetism, 5241 Broad Branch Road, Washington, DC 20008, USA (c) Departments of Geology and Physics & Astronomy, Bates College, Lewiston, ME 04240, USA (d) Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA (e) Institute for Astronomy, 640 North A'ohoku Place, Hilo, HI 96720, USA Article History: Received 17 December 2009; Revised 25 February 2010; Accepted 6 March 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2010.02.017 Byline: Mark Willman (a), Robert Jedicke (a), Nicholas Moskovitz (b), David NesvornA1/2 (c), David VokrouhlickA1/2 (d), Thais Mothe-Diniz (e) Keywords: Asteroids, Surfaces; Spectrophotometry; Spectroscopy Abstract: We have extended our earlier work on space weathering of the youngest S-complex asteroid families to include results from asteroid clusters with ages Author Affiliation: (a) Institute for Astronomy, University of Hawai'i at Manoa, 2680 Woodlawn Drive, Honolulu, HI 96822, USA (b) Department of Terrestrial Magnetism, 5241 Broad Branch Road, NW, Washington, DC 20008, USA (c) Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 400, Boulder, CO 80302, USA (d) Institute of Astronomy, Charles University, V HoleA oviAkach 2, CZ-18000 Prague 8, Czech Republic (e) UFRJ/Observatorio do Valongo, Ladeira Pedro AntA[acute accent]nio, 43, 20080-090 Rio de Janeiro/RJ, Brazil Article History: Received 7 December 2009; Revised 25 February 2010; Accepted 26 February 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2008.07.006 Byline: Nicholas A. Moskovitz (a), Robert Jedicke (a), Eric Gaidos (b)(c), Mark Willman (a), David NesvornA1/2 (d), Ronald Fevig (e), A1/2eljko IveziA (f) Keywords: Asteroids; Spectroscopy; Asteroids; composition; Asteroid Vesta Abstract: We present the observational results of a survey designed to target and detect asteroids whose photometric colors are similar to those of Vesta family members and thus may be considered as candidates for having a basaltic composition. Fifty basaltic candidates were selected with orbital elements that lie outside of the Vesta dynamical family. Optical and near-infrared spectra were used to assign a taxonomic type to 11 of the 50 candidates. Ten of these were spectroscopically confirmed as V-type asteroids, suggesting that most of the candidates are basaltic and can be used to constrain the distribution of basaltic material in the Main Belt. Using our catalog of V-type candidates and the success rate of the survey, we calculate unbiased size-frequency and semi-major axis distributions of V-type asteroids. These distributions, in addition to an estimate for the total mass of basaltic material, suggest that Vesta was the predominant contributor to the basaltic asteroid inventory of the Main Belt, however scattered planetesimals from the inner Solar System (a Author Affiliation: (a) Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA (b) Department of Geology and Geophysics, University of Hawaii, POST 701, 1680 East-West Road, Honolulu, HI 96822, USA (c) NASA Astrobiology Institute, University of Hawaii, PSB 213, 2565 McCarthy Mall, Honolulu, HI 96822, USA (d) Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 400, Boulder, CO 80302, USA (e) Lunar & Planetary Laboratory, University of Arizona, 1629 University Blvd., Tucson, AZ 85721-0092, USA (f) Department of Astronomy, University of Washington, PO Box 351580, Seattle, WA 98195-1580, USA Article History: Received 22 November 2007; Revised 27 June 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2008.02.007 Byline: Mark Willman (a), Robert Jedicke (a), David NesvornA1/2 (b), Nicholas Moskovitz (a), A1/2eljko IveziA (c), Ronald Fevig (d) Keywords: Asteroids; surfaces Abstract: We have obtained moderate S/N ([approximately equal to]85) spectra at a realized resolution of R[approximately equal to]100 for 11 members of the Iannini family, until recently the youngest known family at under 5 million years of age [NesvornA1/2, D., Bottke, W.F., Levison, H.F., Dones, L., 2003. Astrophys. J. 591, 486-497, 720-771]. The spectra were acquired using the Echellette Spectrograph and Imager in its low-resolution prism mode on the Keck II telescope. The family members belong to the S-complex of asteroids with perhaps some K class members. The Iannini family members' average spectral slope, defined as the slope of the best-fit line constrained to pivot about 1 at 550 nm, is (0.30[+ or -]0.04)/[mu]m, matching the (0.26[+ or -]0.03)/[mu]m reported by Jedicke et al. [Jedicke, R., NesvornA1/2, D., Whiteley, R.J., IveziA, A1/2., JuriA, M., 2004. Nature 429, 275-277] using SDSS [IveziA, A1/2., JuriA, M., Lupton, R.H., Tabachnik, S., Quinn, T., 2002. In: Tyson, J.A., Wolff, S. (Eds.), Survey and Other Telescope Technologies and Discoveries. In: Proc. SPIE, vol. 4836. SPIE, Bellingham, pp. 98-103] color photometry. Using our spectra for this family as well as new observations of Karin family members [Vernazza, P., Birlan, M., Rossi, A., Dotto, E., NesvornA1/2, D., Brunetto, R., Fornasier, S., Fulchignoni, M., Renner, S., 2006. Astron. Astrophys. 460, 945-951] and new classifications of some older families we have revised the space weathering rate of S-complex asteroids originally determined by Jedicke et al. [Jedicke, R., NesvornA1/2, D., Whiteley, R.J., IveziA, A1/2., JuriA, M., 2004. Nature 429, 275-277]. Following Jedicke et al. [Jedicke, R., NesvornA1/2, D., Whiteley, R.J., IveziA, A1/2., JuriA, M., 2004. Nature 429, 275-277] we parameterize the space weathering rate of the principal component color of the spectrum (PC.sub.1), which is correlated with the spectral slope, as PC.sub.1(t)=PC.sub.1(0)+[DELTA]PC.sub.1[1-exp.sup.-(t/I).sup.[alpha]]. Our revised rate suggests that the characteristic time scale for space weathering is I=570[+ or -]220 Myr and that new S-complex clusters will have an initial color of PC.sub.1(0)=0.31[+ or -]0.04. The revised time scale is in better agreement with lab measurements and our measurements support the use of space weathering as a dating method. Under the assumption that all the spectra should be identical, since the members all derive from the same parent body and are presumably covered with similar regolith, we combined them to obtain a high-S/N composite spectrum for the family. The combined spectrum is within the S-complex. Author Affiliation: (a) Institute for Astronomy, University of Hawaii'i at Manoa, 2680 Woodlawn Drive, Honolulu, HI 96822, USA (b) Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 400, Boulder, CO 80302, USA (c) Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195-1580, USA (d) Lunar & Planetary Laboratory, University of Arizona, 1629 University Blvd., Tucson, AZ 85721-0092, USA Article History: Received 18 July 2007; Revised 2 February 2008

Asteroid pairs are genetically related asteroids that recently separated (

In 2018 December, the main-belt asteroid (6478) Gault was reported to display activity. Gault is an asteroid belonging to the Phocaea dynamical family and was not previously known to be active, nor was any other member of the Phocaea family. In this work, we present the results of photometric and spectroscopic observations that commenced soon after the discovery of activity. We obtained observations over two apparitions to monitor its activity, rotation period, composition, and possible non-gravitational orbital evolution. We find that Gault has a rotation period of P  = 2.4929 ± 0.0003 h with a light-curve amplitude of 0.06 magnitude. This short rotation period close to the spin barrier limit is consistent with Gault having a density no smaller than ρ = 1.85 g cm−3 and its activity being triggered by the YORP (Yarkovsky–O'Keefe–Radzievskii–Paddack) spin-up mechanism. Analysis of the Gault phase curve over phase angles ranging from 0.4° to 23.6° provides an absolute magnitude of H  = 14.81 ± 0.04, G 1 = 0.25 ± 0.07, and G 2 = 0.38 ± 0.04. Model fits to the phase curve find the surface regolith grain size constrained between 100 and 500 |$\rm {\mu }$| m. Using relations between the phase curve and albedo, we determine that the geometrical albedo of Gault is p v = 0.26 ± 0.05 corresponding to an equivalent diameter of |$D = 2.8^{+0.4}_{-0.2}$| km. Our spectroscopic observations are all consistent with an ordinary chondrite-like composition (S, or Q-type in the Bus-DeMeo taxonomic classification). A search through archival photographic plate surveys found previously unidentified detections of Gault dating back to 1957 and 1958. Only the latter had been digitized, which we measured to nearly double the observation arc of Gault. Finally, we did not find any signal of activity during the 2020 apparition or non-gravitational effects on its orbit. [ABSTRACT FROM AUTHOR]

Context. Basaltic V-type asteroids play a crucial role in studies of Solar System evolution and planetesimal formation. Comprehensive studies of their physical, dynamical, and statistical properties provide insight into these processes. Thanks to wide surveys, currently there are numerous known V-type and putative V-type asteroids, allowing a detailed statistical analysis. Aims. Our main goal is to analyze I corrected for US language conventions in this paper the currently available large sample of V-type spin rates, to find signatures of the non-gravitational Yarkovsky–O'Keefe–Radzievskii–Paddack (YORP) effect among the different V-type populations, and to estimate the spin barrier and critical density for V-type asteroids. Our intention is to increase the pool of information about the intriguing V-types. Methods. We collected rotational periods from the literature for spectrally confirmed V-types, putative V-types, and Vesta family members. Through spectroscopic observations we confirmed their taxonomic type and verified the high confirmation rates of the putative V-types. We combined the collected periods with periods estimated in this manuscript and produced rotational frequency distributions. We determined the spin barrier in the frequency–light curve amplitude space for V-type asteroids. Results. We analyzed rotational periods of 536 asteroids in our sample. As expected, due to the small size of the objects analyzed, the frequency distributions for the Vesta family and the V-types outside the family are inconsistent with a Maxwellian shape. The Vesta family shows an excess of slow-rotators. V-types outside the family show an excess of both slow and fast rotators. Interestingly, we found that the population of V-types outside the Vesta family shows a significant excess of fast rotators compared to the Vesta family. The estimated critical density for V-type asteroids exceeds ρc = 2.0 g cm−3, which surpasses the previous estimates. Conclusions. We demonstrated that V-type asteroids have been influenced by the thermal radiation YORP effect and that their critical spin rate is higher than for C-type asteroids. The population of V-types outside the Vesta family shows a significant excess of fast rotators compared to the Vesta family. We hypothesize that the objects that evolved from the Vesta family though the Yarkovsky drift are also more susceptible to the YORP effect. Objects for which YORP has not yet had enough time to act and those that are more YORP resistant will be left in the family, which explains the relatively small proportion of fast rotators being left. The YORP timescale must thus be similar to the migration timescale for those objects. [ABSTRACT FROM AUTHOR]

Context. Asteroid (2579) Spartacus is a small V-type object located in the inner main belt. This object shows spectral characteristics unusual for typical Vestoids, which may indicate an origin deeper than average within Vesta or an origin from an altogether different parent body. Aims. Our main goal is to study the origin of Spartacus. We derive the spin of Spartacus and a convex shape model of Spartacus in order to increase the knowledge of the body's physical properties. The rotational parameters are then used to investigate dynamical evolution of the object as well as to distinguish regions sampled by spectral observations to determine whether its surface displays heterogeneity. Methods. We collected lightcurves available from the literature (oppositions of 2009, 2012) and obtained additional photometric observations at various telescopes in 2016, 2017, and 2018. We used the lightcurve inversion method to derive a spin and convex shape model. We have collected spectral observations over two rotational periods of Spartacus and determined its spectral parameters using the modified Gaussian model (MGM). We then dynamically integrated the orbital elements of Spartacus, taking into account existing information, including its thermal properties, size and the derived spin axis orientation. Results. We find two models for (2579) Spartacus: (a) λ = 312° ± 5°, β = −57° ± 5° and (b) λ = 113° ± 5°, β = −60° ± 5° both retrograde. We find that the drift direction for Spartacus is consistent with separation from Vesta, and after a backward integration of 1 Gyr the asteroid reaches the boundary of the family. We did not observe spectral variations with rotation, thus the body most likely has a homogeneous surface. Additionally, new spectral analysis indicates that the 1.0 and 2.0 μm band centers are within ranges that are typical for Vestoids while the area ratio of these bands is about half that of typical Vestoids. Conclusions. The asteroid (2579) Spartacus is in retrograde rotation and has a drift direction consistent with an origin from Vesta. The revised spectral band centers are within ranges typical for Vestoids, while band area ratio (BAR) is unusually low compared to that of other V-types. The dynamical model shows that the asteroid could have migrated to its current location from the edges of the Vesta family within 1 Gyr, but an origin from an earlier impact on Vesta could also be plausible. [ABSTRACT FROM AUTHOR]

Bolides are detected by the Geostationary Lightning Mapper onboard the GOES‐16 weather satellite, which takes images of Earth at a rate of 500 Hz in a 1.1 nm wide pass band centered on 777.4 nm wavelength. Ten case studies are discussed. These initial results were obtained using the Level 0 data received during the nonoperational in‐orbit postlaunch test period. GLM positions and timings are sufficiently accurate to assist in trajectory and orbit reconstruction. GLM samples the light curve nearly completely, unaffected by onboard and downlink processes tailored to lightning data. Sufficient data on the instantaneous background scene are provided to reconstruct the baseline drift in the brightest pixels. The agreement to within a factor of 2–3 between measured total radiated energy from GLM and that derived from other space‐borne observations implies that during the bolide's peak brightness the GLM pass band is dominated by continuum emission, rather than O I line emission. The reported flux is corrected for angle‐from‐nadir shifts in the central wavelength of the pass band, which overestimates continuum flux by only up to 20% for most of the GLM field of view, but more so if the bolide is observed far from nadir. Assuming a 6000 K blackbody spectrum, GLM is able to detect bolides with peak visual magnitude (at a normalized 100 km distance) brighter than about −14 in nighttime, and slightly brighter in daytime. [ABSTRACT FROM AUTHOR]

Boulders, rocks and regolith on fast rotating asteroids (<2.5 hours) are modeled to slide towards the equator due to a strong centrifugal force and a low cohesion force. As a result, regions of fresh subsurface material can be exposed. Therefore, we searched for color variation on small and fast rotating asteroids. We describe a novel technique in which the asteroid is simultaneously observed in the visible and near-IR wavelength range. In this technique, brightness changes due to atmospheric extinction effects can be calibrated across the visible and near-IR images. We use V- and J-band filters since the distinction in color between weathered and unweathered surfaces on ordinary chondrite-like bodies is most prominent at these wavelengths and can reach ~25%. To test our method, we observed 3 asteroids with Cerro Tololo's 1.3 m telescope. We find ~5% variation of the mean V-J color, but do not find any clearly repeating color signature through multiple rotations. This suggests that no landslides occurred within the timescale of space weathering, or that Landslides occurred but the exposed patches are too small for the measurements' uncertainty. [ABSTRACT FROM PUBLISHER]

- We model the heating of a primordial planetesimal by decay of the short-lived radionuclides 26Al and 60Fe to determine (1) the time scale on which melting will occur, (2) the minimum size of a body that will produce silicate melt and differentiate, (3) the migration rate of molten material within the interior, and (4) the thermal consequences of the transport of 26Al in partial melt. Our models incorporate results from previous studies of planetary differentiation and are constrained by petrologic (i.e., grain-size distributions), isotopic (e.g., 207Pb-206Pb and 182Hf-182W ages), and mineralogical properties of differentiated achondrites. We show that formation of a basaltic crust via melt percolation was limited by the formation time of the body, matrix grain size, and viscosity of the melt. We show that low viscosity (<1 Pa · s) silicate melt can buoyantly migrate on a time scale comparable to the mean life of 26Al. The equilibrium partitioning of Al into silicate partial melt and the migration of that melt acts to dampen internal temperatures. However, subsequent heating from the decay of 60Fe generated melt fractions in excess of 50%, thus completing differentiation for bodies that accreted within 2 Myr of CAI formation (i.e., the onset of isotopic decay). Migration and concentration of 26Al into a crust results in remelting of that crust for accretion times less than 2 Myr and for bodies >100 km in size. Differentiation would be most likely for planetesimals larger than 20 km in diameter that accreted within approximately 2.7 Myr of CAI formation. [ABSTRACT FROM AUTHOR]

The phase or orbital light curves of extrasolar terrestrial planets in reflected or emitted light will contain information about their atmospheres and surfaces complementary to data obtained by other techniques such as spectrosopy. We show calculated light curves at optical and thermal infrared wavelengths for a variety of Earth-like and Earth-unlike planets. We also show that large satellites of Earth-sized planets are detectable, but may cause aliasing effects if the lightcurve is insufficiently sampled. [ABSTRACT FROM PUBLISHER]

We investigated the magnitude-phase relation of (162173) 1999 JU3, a target asteroid for the JAXA Hayabusa 2 sample return mission. We initially employed the International Astronomical Union's H-G formalism but found that it fits less well using a single set of parameters. To improve the inadequate fit, we employed two photometric functions: the Shevchenko and Hapke functions. With the Shevchenko function, we found that the magnitude-phase relation exhibits linear behavior in a wide phase angle range (α = 5°-75°) and shows weak nonlinear opposition brightening at α < 5°, providing a more reliable absolute magnitude of HV = 19.25 ± 0.03. The phase slope (0.039 ± 0.001 mag deg–1) and opposition effect amplitude (parameterized by the ratio of intensity at α = 0.°3 to that at α = 5°, I(0.°3)/I(5°) = 1.31 ± 0.05) are consistent with those of typical C-type asteroids. We also attempted to determine the parameters for the Hapke model, which are applicable for constructing the surface reflectance map with the Hayabusa 2 onboard cameras. Although we could not constrain the full set of Hapke parameters, we obtained possible values, w = 0.041, g = –0.38, B0 = 1.43, and h = 0.050, assuming a surface roughness parameter = 20°. By combining our photometric study with a thermal model of the asteroid, we obtained a geometric albedo of pv = 0.047 ± 0.003, phase integral q = 0.32 ± 0.03, and Bond albedo AB = 0.014 ± 0.002, which are commensurate with the values for common C-type asteroids. [ABSTRACT FROM AUTHOR]

Abstract: We present the thermal infrared (5–35μm) spectrum of 956 Elisa as measured by the Spitzer Infrared Spectrograph (“IRS”; Houck, J.R. et al. [2004]. Astrophys. J. Suppl. 154, 18–24) together with new groundbased lightcurve data and near-IR spectra. From the visible lightcurve photometry, we determine a rotation period of 16.494±0.001h, identify the rotational phase of the Spitzer observations, and estimate the visible absolute magnitude (H V ) at that rotational phase to be 12.58±0.04. From radiometric analysis of the thermal flux spectrum, we find that at the time of observation 956 Elisa had a projected radius of 5.3±0.4km with a visible albedo p V =0.142±0.022, significantly lower than that of the prototype V-type asteroid, 4 Vesta. (This corresponds to a radius of 5.2±0.4km at lightcurve mean.) Analysis with the standard thermal model (STM) results in a sub-solar temperature of 292.3± 2.8 K and beaming parameter η =1.16±0.05. Thermophysical modeling places a lower limit of on the thermal inertia of the asteroid’s surface layer (if the surface is very smooth) but more likely values fall between 30 and depending on the sense of rotation. The emissivity spectrum, calculated by dividing the measured thermal flux spectrum by the modeled thermal continuum, exhibits mineralogically interpretable spectral features within the 9–12μm reststrahlen band, the 15–16.5μm Si–O–Si stretching region, and the 16–25μm reststrahlen region that are consistent with pyroxene of diogenitic composition: extant diogenitic pyroxenes fall within the narrow compositional range Wo2±1En74±2Fs24±1. Spectral deconvolution of the 9–12μm reststrahlen features indicates that up to ≈20% olivine may also be present, suggesting an olivine-diogenite-like mineralogy. The mid-IR spectrum is inconsistent with non-cumulate eucrite as the major component on the surface of 956 Elisa, although cumulate eucrite material may be present at abundances lower than that of the diogenite component. Analysis of new near-IR spectra of 956 Elisa with the Modified Gaussian Model (MGM; Sunshine, J.M., Pieters, C.M., Pratt, S.F. [1990]. J. Geophys. Res. 95 (May), 6955–6966) results in two pyroxene compositions: 75% magnesian low-Ca pyroxene and 25% high-Ca pyroxene. High-Ca pyroxene is not evident in the mid-IR data, but may belong to a component that is underrepresented in the mid-IR spectrum either because of its spatial distribution on the asteroid or because of its particle size. High-Ca pyroxenes that occur as exsolution lamellae may also be more evident spectrally in the NIR than in the mid-IR. In any case, we find that the mid-IR spectrum of 956 Elisa is dominated by emission from material of diogenite-like composition, which has very rarely been observed among asteroids. [Copyright &y& Elsevier]

Highlights • We confirm 21 olivine-dominated spectral A-type asteroids in the main belt. • We determine 0.16% of the main belt is A-type. • The distribution of A-types as a function of semi-major axis is relatively flat. • We reaffirm there is no significant undiscovered A-type material down to −2 km. • We find no statistically significant relationship with A-types and asteroid families. Abstract Differentiated asteroids are rare in the main asteroid belt despite evidence for ∼ 100 distinct differentiated bodies in the meteorite record. We have sought to understand why so few main-belt asteroids differentiated and where those differentiated bodies or fragments reside. Using the Sloan Digital Sky Survey (SDSS) to search for a needle in a haystack we identify spectral A-type asteroid candidates, olivine-dominated asteroids that may represent mantle material of differentiated bodies. We have performed a near-infrared spectral survey with SpeX on the NASA IRTF and FIRE on the Magellan Telescope. We report results from having doubled the number of known A-type asteroids. We deduce a new estimate for the overall abundance and distribution of this class of olivine-dominated asteroids. We find A-type asteroids account for less than 0.16% of all main-belt objects larger than 2 km and estimate there are a total of ∼ 600 A-type asteroids above that size. They are found rather evenly distributed throughout the main belt, are even detected at the distance of the Cybele region, and have no statistically significant concentration in any asteroid family. We conclude the most likely implication is the few fragments of olivine-dominated material in the main belt did not form locally, but instead were implanted as collisional fragments of bodies that formed elsewhere. [ABSTRACT FROM AUTHOR]