Query Results from the ADS Database Retrieved 21 abstracts, starting with number 1. Total number selected: 13154. TY - Journal T1 - Predictions for the detection of Earth and Mars Trojan asteroids by the Gaia satellite A1 - Todd, M. A1 - Tanga, P. A1 - Coward, D. M. A1 - Zadnik, M. G. JO - Monthly Notices of the Royal Astronomical Society VL - 437 Y1 - 2014/2/1 SP - 4019 EP - 4026 KW - methods: numerical/ methods: observational/ methods: statistical/ celestial mechanics/ minor planets/ asteroids: general/ planets and satellites: general UR - http://adsabs.harvard.edu/abs/2014MNRAS.437.4019T N2 - The European Space Agency Gaia satellite, planned for launch in late 2013, will perform systematic astrometric observations of the whole sky over a five year period. During this mission, many thousands of Solar System objects down to magnitude V = 20 will be observed including near-Earth asteroids and objects at solar elongations as low as 45°, which are difficult to observe with ground-based telescopes. We simulated the detection of Trojan asteroids in the orbits of Earth and Mars by Gaia. We find that Gaia will not detect the Earth Trojan 2010 TK7 although it will detect any Earth Trojans with diameters larger than 600 m. We also find that Gaia will detect the currently known Mars Trojans and could discover more than 100 new Mars Trojans as small as 400 m in diameter. The results of the Gaia mission will test the predictions about the Mars Trojan asteroid population and lead to greater understanding about the evolution of the Solar System. DO - 10.1093/mnras/stt2223 C1 - eprint: arXiv:1311.3372 SN - 0035-8711 ER - TY - Journal T1 - Tidal end states of binary asteroid systems with a nonspherical component A1 - Taylor, Patrick A. A1 - Margot, Jean-Luc JO - Icarus VL - 229 Y1 - 2014/2/1 SP - 418 EP - 422 UR - http://adsabs.harvard.edu/abs/2014Icar..229..418T N2 - We derive the locations of the fully synchronous end states of tidal evolution for binary asteroid systems having one spherical component and one oblate- or prolate-spheroid component. Departures from a spherical shape, at levels observed among binary asteroids, can result in the lack of a stable tidal end state for particular combinations of the system mass fraction and angular momentum, in which case the binary must collapse to contact. We illustrate our analytical results with near-Earth Asteroids (8567) 1996 HW1, (66391) 1999 KW4, and 69230 Hermes. DO - 10.1016/j.icarus.2013.11.008 C1 - eprint: arXiv:1312.0537 SN - 0019-1035 ER - TY - Journal T1 - Unexpected D-type interlopers in the inner main belt A1 - DeMeo, Francesca E. A1 - Binzel, Richard P. A1 - Carry, Benoiˆt A1 - Polishook, David A1 - Moskovitz, Nicholas A. JO - Icarus VL - 229 Y1 - 2014/2/1 SP - 392 EP - 399 UR - http://adsabs.harvard.edu/abs/2014Icar..229..392D N2 - Very red featureless asteroids (spectroscopic D-types) are expected to have formed in the outer Solar System far from the Sun. They comprise the majority of asteroids in the Jupiter Trojan population, and are also commonly found in the outer main belt and among Hildas. The first evidence for D-types in the inner and middle parts of the main belt was seen in the Sloan Digital Sky Survey (SDSS). Here we report follow-up observations of SDSS D-type candidates in the near-infrared. Based on follow up observations of 13 SDSS D-type candidates, we find a Ëœ20% positive confirmation rate. Known inner belt D-types range in diameter from roughly 7 to 30 km. Based on these detections we estimate there are Ëœ100 inner belt D-types with diameters between 2.5 and 20 km. The lower and upper limits for total mass of inner belt D-types is 2 × 1016 kg to 2 × 1017 kg which represents 0.01--0.1% of the mass of the inner belt. The inner belt D-types have albedos at or above the upper end typical for D-types which raises the question as to whether these inner belt bodies represent only a subset of D-types, they have been altered by external factors such as weathering processes, or if they are compositionally distinct from other D-types. All D-types and candidates have diameters less than 30 km, yet there is no obvious parent body in the inner belt. Dynamical models have yet to show how D-types originating from the outer Solar System could penetrate into the inner reaches of the main belt under current scenarios of planet formation and subsequent Yarkovsky drift. DO - 10.1016/j.icarus.2013.11.026 C1 - eprint: arXiv:1312.2962 SN - 0019-1035 ER - TY - Journal T1 - The preliminary analysis of the 4179 Toutatis snapshots of the Chang'E-2 flyby A1 - Zou, Xiaoduan A1 - Li, Chunlai A1 - Liu, Jianjun A1 - Wang, Wenrui A1 - Li, Han A1 - Ping, Jinsong JO - Icarus VL - 229 Y1 - 2014/2/1 SP - 348 EP - 354 UR - http://adsabs.harvard.edu/abs/2014Icar..229..348Z N2 - On 2012 December, 13, 08:30 (UTC), Chang'E-2 flew by Asteroid 4179 Toutatis in deep space 7 million kilometers away from Earth. The flyby mission returned clear optical images of Toutatis for the first time. The flyby distance and image pixel scale were calculated from the image size of the asteroid compared to a predicted view of an earlier radar shape model. We compared the similarities and differences in both the radar model and the CE-2 photo mosaic, and measured the craters and lumps on the surface of Toutatis. We preliminarily analyzed the topography of the Toutatis surface. We found that the density of craters on the small lobe is less than that on the big lobe. DO - 10.1016/j.icarus.2013.11.002 SN - 0019-1035 ER - TY - Journal T1 - Assessment of the 2880 impact threat from Asteroid (29075) 1950 DA A1 - Farnocchia, D. A1 - Chesley, S. R. JO - Icarus VL - 229 Y1 - 2014/2/1 SP - 321 EP - 327 UR - http://adsabs.harvard.edu/abs/2014Icar..229..321F N2 - In this paper we perform an assessment of the 2880 Earth impact risk for Asteroid (29075) 1950 DA. To obtain reliable predictions we analyze the contribution of the observational dataset and the astrometric treatment, the numerical error in the long-term integration, and the different accelerations acting on the asteroid. The main source of uncertainty is the Yarkovsky effect, which we statistically model starting from 1950 DA's available physical characterization, astrometry, and dynamical properties. Before the release of 2012 radar data, this modeling suggests that 1950 DA has 99% likelihood of being a retrograde rotator. By using a 7-dimensional Monte Carlo sampling we map 1950 DA's uncertainty region to the 2880 close approach b-plane and find a 5×10-4 impact probability. With the recently released 2012 radar observations, the direct rotation is definitely ruled out and the impact probability decreases to 2.5×10-4. DO - 10.1016/j.icarus.2013.09.022 C1 - eprint: arXiv:1310.0861 SN - 0019-1035 ER - TY - Journal T1 - Stability of rubble-pile satellites A1 - Sharma, Ishan JO - Icarus VL - 229 Y1 - 2014/2/1 SP - 278 EP - 294 UR - http://adsabs.harvard.edu/abs/2014Icar..229..278S N2 - We consider the stability of rubble-pile satellites that are held together by their own gravity. A satellite is said to be stable whenever it is both orbitally and structurally stable to both orbital and structural perturbations. We restrict attention to satellites whose dimensions are small compared to their respective orbital radii and their associated planets' sizes. In this case, we show that a satellite is stable whenever it is orbitally stable to orbital perturbations and structurally stable to structural perturbations. Orbital stability is investigated by a spectral analysis, while structural stability is probed by appropriately extending the work of Sharma [Sharma, I., 2012. Stability of rotating non-smooth complex fluids. J. Fluid Mech. 708, 71--99; Sharma, I., 2013. Structural stability of rubble-pile asteroids. Icarus 223, 367--382]. The stability test is then applied to planetary satellites of the Solar System that are suspected to be granular aggregates, including many of the recently discovered smaller moons of the giant planets. DO - 10.1016/j.icarus.2013.09.023 SN - 0019-1035 ER - TY - Journal T1 - Transmission infrared spectra (2--25 mum) of carbonaceous chondrites (CI, CM, CV--CK, CR, C2 ungrouped): Mineralogy, water, and asteroidal processes A1 - Beck, P. A1 - Garenne, A. A1 - Quirico, E. A1 - Bonal, L. A1 - Montes-Hernandez, G. A1 - Moynier, F. A1 - Schmitt, B. JO - Icarus VL - 229 Y1 - 2014/2/1 SP - 263 EP - 277 UR - http://adsabs.harvard.edu/abs/2014Icar..229..263B N2 - In this work, infrared transmission spectra (2--25 mum range, 5000--400 cm-1) of 40 carbonaceous chondrites were analyzed (21 CMs, 5 CVs, 6 CRs, 3 CKs, 3 C2s and 2 CIs). All these meteorite groups are known to have experienced significant aqueous alteration (except the CKs). These IR measurements provide information about the parent body processes experienced, as well as spectra for comparison with observations of Solar System small bodies and possibly with astronomical observations of accretion and debris disks. DO - 10.1016/j.icarus.2013.10.019 SN - 0019-1035 ER - TY - Journal T1 - Hypervelocity impacts on asteroids and momentum transfer I. Numerical simulations using porous targets A1 - Jutzi, Martin A1 - Michel, Patrick JO - Icarus VL - 229 Y1 - 2014/2/1 SP - 247 EP - 253 UR - http://adsabs.harvard.edu/abs/2014Icar..229..247J N2 - In this paper, we investigate numerically the momentum transferred by impacts of small (artificial) projectiles on asteroids. The study of the momentum transfer efficiency as a function of impact conditions and of the internal structure of an asteroid is crucial for performance assessment of the kinetic impactor concept of deflecting an asteroid from its trajectory. The momentum transfer is characterized by the so-called momentum multiplication factor beta, which has been introduced to define the momentum imparted to an asteroid in terms of the momentum of the impactor. Here we present results of code calculations of the beta factor for porous targets, in which porosity takes the form of microporosity and/or macroporosity. The results of our study using a large range of impact conditions indicate that the momentum multiplication factor beta is small for porous targets even for very high impact velocities (beta<2 for vimp<=15km/s), which is consistent with published scaling laws and results of laboratory experiments (Holsapple, K.A., Housen, K.R. [2012]. Icarus 221, 875--887; Holsapple, K.A., Housen, K.R. [2013]. Proceedings of the IAA Planetary Defense Conference 2013, Flagstaff, USA). It is found that both porosity and strength can have a large effect on the amount of transferred momentum and on the scaling of beta with impact velocity. On the other hand, the macroporous inhomogeneities considered here do not have a significant effect on beta. DO - 10.1016/j.icarus.2013.11.020 SN - 0019-1035 ER - TY - Journal T1 - On the non-uniform distribution of the angular elements of near-Earth objects A1 - JeongAhn, Youngmin A1 - Malhotra, Renu JO - Icarus VL - 229 Y1 - 2014/2/1 SP - 236 EP - 246 UR - http://adsabs.harvard.edu/abs/2014Icar..229..236J N2 - We examine the angular distributions of near-Earth objects (NEOs) which are often regarded as uniform. The apparent distribution of the longitude of ascending node, Omega, is strongly affected by well-known seasonal effects in the discovery rate of NEOs. The deviation from the expected pi-periodicity in the apparent distribution of Omega indicates that its intrinsic distribution is slightly enhanced along a mean direction, Omega‾=111°; approximately 53% of NEOs have Omega values within ±90° of Omega‾. We also find that each subgroup of NEOs (Amors, Apollos and Atens) has different observational selection effects which cause different non-uniformities in the apparent distributions of their arguments of perihelion omega, and longitudes of perihelion varpi. For their intrinsic distributions, our analysis reveals that the Apollo asteroids have non-uniform omega due to secular dynamics associated with inclination-eccentricity-omega coupling, and the Amors' varpi distribution is peaked towards the secularly forced eccentricity vector. The Apollos' omega distribution is axial, favoring values near 0° and 180°; the two quadrants centered at 0° and 180° account for 55% of the Apollos' omega values. The Amors' varpi distribution peaks near varpi‾=4°; 61% of Amors have varpi within ±90° of this peak. We show that these modest but statistically significant deviations from uniform random distributions of angular elements are owed to planetary perturbations, primarily Jupiter's. It is remarkable that this strongly chaotic population of minor planets reveals the presence of Jupiter in its angular distributions. DO - 10.1016/j.icarus.2013.10.030 C1 - eprint: arXiv:1310.5457 SN - 0019-1035 ER - TY - Journal T1 - Scheila's scar: Direct evidence of impact surface alteration on a primitive asteroid A1 - Bodewits, D. A1 - Vincent, J.-B. A1 - Kelley, M. S. P. JO - Icarus VL - 229 Y1 - 2014/2/1 SP - 190 EP - 195 UR - http://adsabs.harvard.edu/abs/2014Icar..229..190B N2 - Asteroid (596) Scheila was the first object for which the immediate aftermath of an inter-asteroidal collision was observed. In December 2010, the 113 km-sized asteroid was impacted by a smaller asteroid of less than 100 m in diameter. The scale of the impactor was established by observations of fading ejecta plumes. Comparison of the lightcurves obtained before and after the impact allowed us to assess how much of Scheila's surface was altered. Cratering physics based on the impactor size suggests that the size of the affected area is larger than expected, (effective radii of 3.5--10 km depending on the change in the albedo of the surface). Similar but more localized albedo changes have been observed on Vesta and the martian moons, but are not understood. Empirical laws describing ejecta blankets however indicate that at distances between 3.5 and 10 km from the crater, Scheila's surface would be covered by a thin layer 2 mm to 2 cm thick. This dusting, possibly mixed with bright impactor material may be enough to explain to observed brightness increase. Our results show that sub-critical impacts may play a significant role in processing the surfaces of asteroids. The large effect of small impacts on asteroidal lightcurves complicate shape modeling. DO - 10.1016/j.icarus.2013.11.003 C1 - eprint: arXiv:1310.8515 SN - 0019-1035 ER - TY - Journal T1 - Block distributions on Itokawa A1 - Mazrouei, S. A1 - Daly, M. G. A1 - Barnouin, O. S. A1 - Ernst, C. M. A1 - DeSouza, I. JO - Icarus VL - 229 Y1 - 2014/2/1 SP - 181 EP - 189 UR - http://adsabs.harvard.edu/abs/2014Icar..229..181M N2 - Asteroid 25143 Itokawa is a small elongated asteroid with two distinct parts. The evolution of this two-part body has been the source of speculation. The scenarios for the formation of this asteroid include: two-body capture, catastrophic disruption and rapid reaccretion, YORP spin-up and mass shedding, and disruption (or partial disruption) with two-body reaccretion. In this paper we use the global and regional analyses of block populations and size--frequency distributions as evidence of the probable evolutionary history of Itokawa. The block sample used in this study is believed to be complete for blocks of size >6 m and consists of a sample more than twice as large as previous known studies. DO - 10.1016/j.icarus.2013.11.010 SN - 0019-1035 ER - TY - Journal T1 - Near-infrared spectroscopy of 3:1 Kirkwood Gap asteroids II: Probable and plausible parent bodies; primitive and differentiated A1 - Fieber-Beyer, Sherry K. A1 - Gaffey, Michael J. JO - Icarus VL - 229 Y1 - 2014/2/1 SP - 99 EP - 108 UR - http://adsabs.harvard.edu/abs/2014Icar..229...99F N2 - The 3:1 Kirkwood Gap asteroids are a mineralogically diverse set of asteroids located in a region that delivers meteoroids into Earth-crossing orbits. Mineralogical characterizations of asteroids in/near the 3:1 Kirkwood Gap can be used as a tool to "map" conditions and processes in the early Solar System. The chronological studies of the meteorite types provide a "clock" for the relative timing of those events and processes. By identifying the source asteroids of particular meteorite types, the "map" and "clock" can be combined to provide a much more sophisticated understanding of the history and evolution of the late solar nebula and the early Solar System. DO - 10.1016/j.icarus.2013.11.001 SN - 0019-1035 ER - TY - Journal T1 - Finding Very Small Near-Earth Asteroids using Synthetic Tracking A1 - Shao, Michael A1 - Nemati, Bijan A1 - Zhai, Chengxing A1 - Turyshev, Slava G. A1 - Sandhu, Jagmit A1 - Hallinan, Gregg A1 - Harding, Leon K. JO - The Astrophysical Journal VL - 782 Y1 - 2014/2/1 SP - 1 KW - astrometry/ instrumentation: detectors/ minor planets/ asteroids: general/ techniques: image processing UR - http://adsabs.harvard.edu/abs/2014ApJ...782....1S N2 - We present an approach that significantly increases the sensitivity for finding and tracking small and fast near-Earth asteroids (NEAs). This approach relies on a combined use of a new generation of high-speed cameras which allow short, high frame-rate exposures of moving objects, effectively "freezing" their motion, and a computationally enhanced implementation of the "shift-and-add" data processing technique that helps to improve the signal-to-noise ratio (SNR) for detection of NEAs. The SNR of a single short exposure of a dim NEA is insufficient to detect it in one frame, but by computationally searching for an appropriate velocity vector, shifting successive frames relative to each other and then co-adding the shifted frames in post-processing, we synthetically create a long-exposure image as if the telescope were tracking the object. This approach, which we call "synthetic tracking," enhances the familiar shift-and-add technique with the ability to do a wide blind search, detect, and track dim and fast-moving NEAs in near real time. We discuss also how synthetic tracking improves the astrometry of fast-moving NEAs. We apply this technique to observations of two known asteroids conducted on the Palomar 200 inch telescope and demonstrate improved SNR and 10 fold improvement of astrometric precision over the traditional long-exposure approach. In the past 5 yr, about 150 NEAs with absolute magnitudes H = 28 (~10 m in size) or fainter have been discovered. With an upgraded version of our camera and a field of view of (28 arcmin)2 on the Palomar 200 inch telescope, synthetic tracking could allow detecting up to 180 such objects per night, including very small NEAs with sizes down to 7 m. DO - 10.1088/0004-637X/782/1/1 C1 - eprint: arXiv:1309.3248 SN - 0004-637X ER - TY - Journal T1 - Intermittent Dust Mass Loss from Activated Asteroid P/2013 P5 (PANSTARRS) A1 - Moreno, F. A1 - Licandro, J. A1 - Álvarez-Iglesias, C. A1 - Cabrera-Lavers, A. A1 - Pozuelos, F. JO - The Astrophysical Journal VL - 781 Y1 - 2014/2/1 SP - 118 KW - methods: numerical/ minor planets/ asteroids: individual: P/2013 P5 (PANSTARRS) UR - http://adsabs.harvard.edu/abs/2014ApJ...781..118M N2 - We present observations and models of the dust environment of activated asteroid P/2013 P5 (PANSTARRS). The object displayed a complex morphology during the observations, with the presence of multiple tails. We combined our own observations, all made with instrumentation attached to the 10.4 m Gran Telescopio Canarias on La Palma, with previously published Hubble Space Telescope images to build a model aimed at fitting all the observations. Altogether, the data cover a full three month period of observations which can be explained by intermittent dust loss. The most plausible scenario is that of an asteroid rotating with the spinning axis oriented perpendicular to the orbit plane and losing mass from the equatorial region, consistent with rotational break-up. Assuming that the ejection velocity of the particles (v ~ 0.02-0.05 m s--1) corresponds to the escape velocity, the object diameter is constrained to ~30-130 m for bulk densities 3000-1000 kg m--3. DO - 10.1088/0004-637X/781/2/118 C1 - eprint: arXiv:1312.5895 SN - 0004-637X ER -