Asteroid families classification: Exploiting very large datasets
TL;DR: A new approach to the asteroid family classification by combining the Hierarchical Clustering Method (HCM) with a method to add new members to existing families, which allows to solve some difficult cases of families overlapping in the proper elements space but generated by different collisional events.
About: This article is published in Icarus.The article was published on 2014-09-01 and is currently open access. It has received 191 citations till now. The article focuses on the topics: Asteroid family.
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TL;DR: In this paper, a catalog of proper elements with ∼384,000 numbered asteroids and on new methods is available, including a least squares fit of the two sides of a V-shape plot in the proper semimajor axis, inverse diameter plane to determine the corresponding slopes, an advanced error model for the uncertainties of asteroid diameters, an iterative outlier rejection scheme and quality control.
145 citations
Cites background or methods or result from "Asteroid families classification: E..."
...Then we use the least squares method to fit the data with two straight lines, one for the low proper a (IN side) and the other for the high proper a (OUT side), as in Milani et al. (2014), with an improved outlier rejection procedure, see (Carpino et al., 2003) and Sec....
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...15 (Eunomia): in (Milani et al., 2014)[Table 10] the difference in the slopes for the two sides was much smaller and the fit uncertainty for the OUT side much larger, thus the existence of two separate ages was proposed as possible....
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...…complex families: 135, known to have at least two collisional families, with incompatible physical properties, difficult to disentangle; see e.g., (Milani et al., 2014)[Figure 10]; 221, complex both for dynamical evolution (Vokrouhlický et al., 2006c) and suspect of multiple collisions; 145,…...
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...4 (Vesta): the idea that Vesta might have suffered two large impacts generating two families (Milani et al., 2014)[Sec....
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...In this paper we are going to use the classification of Milani et al. (2014), as updated by Knežević et al. (2014), and the data are presently available on AstDyS1....
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01 May 2012
TL;DR: In this paper, the authors obtained estimates of the Johnson V absolute magnitude (H ) and slope parameters (G ) for 583 main-belt and near-Earth asteroids observed at Ondřejov and Table Mountain Observatory from 1978 to 2011.
Abstract: We obtained estimates of the Johnson V absolute magnitudes ( H ) and slope parameters ( G ) for 583 main-belt and near-Earth asteroids observed at Ondřejov and Table Mountain Observatory from 1978 to 2011. Uncertainties of the absolute magnitudes in our sample are H data with absolute magnitude values given in the MPCORB, Pisa AstDyS and JPL Horizons orbit catalogs. We found that while the catalog absolute magnitudes for large asteroids are relatively good on average, showing only little biases smaller than 0.1 mag, there is a systematic offset of the catalog values for smaller asteroids that becomes prominent in a range of H greater than ∼10 and is particularly big above H ∼ 12. The mean ( H catalog − H ) value is negative, i.e., the catalog H values are systematically too bright. This systematic negative offset of the catalog values reaches a maximum around H = 14 where the mean ( H catalog − H ) is −0.4 to −0.5. We found also smaller correlations of the offset of the catalog H values with taxonomic types and with lightcurve amplitude, up to ∼0.1 mag or less. We discuss a few possible observational causes for the observed correlations, but the reason for the large bias of the catalog absolute magnitudes peaking around H = 14 is unknown; we suspect that the problem lies in the magnitude estimates reported by asteroid surveys. With our photometric H and G data, we revised the preliminary WISE albedo estimates made by Masiero et al. ( Masired, J.R. et al. [2011] . Astrophys. J. 741, 68–89) and Mainzer et al. ( Mainzer, A. et al. [2011b] . Astrophys. J. 743, 156–172) for asteroids in our sample. We found that the mean geometric albedo of Tholen/Bus/DeMeo C/G/B/F/P/D types with sizes of 25–300 km is p V = 0.057 with the standard deviation (dispersion) of the sample of 0.013 and the mean albedo of S/A/L types with sizes 0.6–200 km is 0.197 with the standard deviation of the sample of 0.051. The standard errors of the mean albedos are 0.002 and 0.006, respectively; systematic observational or modeling errors can predominate over the quoted formal errors. There is apparent only a small, marginally significant difference of 0.031 ± 0.011 between the mean albedos of sub-samples of large and small (divided at diameter 25 km) S/A/L asteroids, with the smaller ones having a higher albedo. The difference will have to be confirmed and explained; we speculate that it may be either a real size dependence of surface properties of S type asteroids or a small size-dependent bias in the data (e.g., a bias towards higher albedos in the optically-selected sample of asteroids). A trend of the mean of the preliminary WISE albedo estimates increasing with asteroid size decreasing from D ∼ 30 down to ∼5 km (for S types) showed in Mainzer et al. ( Mainzer, A. et al. [2011a] . Astrophys. J. 741, 90–114) appears to be mainly due to the systematic bias in the MPCORB absolute magnitudes that progressively increases with H in the corresponding range H = 10–14.
140 citations
TL;DR: Asteroids formed in a dynamically quiescent disk but their orbits became gravitationally stirred enough by Jupiter to lead to high-speed collisions as discussed by the authors, and many dozen large asteroids have been disrupted by impacts over the age of the Solar System, producing groups of fragments known as asteroid families.
Abstract: Asteroids formed in a dynamically quiescent disk but their orbits became gravitationally stirred enough by Jupiter to lead to high-speed collisions. As a result, many dozen large asteroids have been disrupted by impacts over the age of the Solar System, producing groups of fragments known as asteroid families. Here we explain how the asteroid families are identified, review their current inventory, and discuss how they can be used to get insights into long-term dynamics of main belt asteroids. Electronic tables of the membership for 122 notable families are reported on the Planetary Data System node.
138 citations
TL;DR: A 4-billion-year-old asteroid family is discovered extending across the entire inner part of the main belt whose members include most of the dark asteroids previously unlinked to families, allowing some original planetesimals to be identified, supporting the view of asteroids being born big.
Abstract: A quarter of known asteroids is associated with more than 100 distinct asteroid families, meaning that these asteroids originate as impact fragments from the family parent bodies. The determination of which asteroids of the remaining population are members of undiscovered families, or accreted as planetesimals from the protoplanetary disk, would constrain a critical phase of planetary formation by unveiling the unknown planetesimal size distribution. We discovered a 4-billion-year-old asteroid family extending across the entire inner part of the main belt whose members include most of the dark asteroids previously unlinked to families. This allows us to identify some original planetesimals, which are all larger than 35 kilometers, supporting the view of asteroids being born big. Their number matches the known distinct meteorite parent bodies.
102 citations
TL;DR: In this paper, the authors presented preliminary diameters and albedos for 7956 asteroids detected in the first year of the NEOWISE Reactivation mission, of which 201 are near-Earth asteroids and 7755 are Main Belt or Mars-crossing asteroids.
Abstract: We present preliminary diameters and albedos for 7956 asteroids detected in the first year of the NEOWISE Reactivation mission. Of those, 201 are near-Earth asteroids and 7755 are Main Belt or Mars-crossing asteroids. 17% of these objects have not been previously characterized using the Near-Earth Object Wide-field Infrared Survey Explorer, or "NEOWISE" thermal measurements. Diameters are determined to an accuracy of ~20% or better. If good-quality H magnitudes are available, albedos can be determined to within ~40% or better.
91 citations
Cites background from "Asteroid families classification: E..."
...Asteroid albedos aid the identification of collisional family members (Masiero et al. 2013; Walsh et al. 2013; Carruba et al. 2013; Milani et al. 2014; Masiero et al. 2015), and allow for basic characterization of asteroid composition (Mainzer et al. 2011c; Grav et al. 2012b; Masiero et al. 2014)....
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References
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California Institute of Technology1, Johns Hopkins University2, University of Arizona3, University of California, Los Angeles4, Monterey Institute for Research in Astronomy5, University of Hawaii6, Harvard University7, Dartmouth College8, Notre Dame High School9, Embry–Riddle Aeronautical University10, Goddard Space Flight Center11, University of Maryland, College Park12
TL;DR: The Wide-field Infrared Survey Explorer (WISE) has surveyed the entire sky at four infrared wavelengths with greatly improved sensitivity and spatial resolution compared to its predecessors, the Infrared Astronomical Satellite and the Cosmic Background Explorer.
Abstract: The Wide-field Infrared Survey Explorer (WISE) has surveyed the entire sky at four infrared wavelengths with greatly improved sensitivity and spatial resolution compared to its predecessors, the Infrared Astronomical Satellite and the Cosmic Background Explorer. NASA's Planetary Science Division has funded an enhancement to the WISE data processing system called "NEOWISE" that allows detection and archiving of moving objects found in the WISE data. NEOWISE has mined the WISE images for a wide array of small bodies in our solar system, including near-Earth objects (NEOs), Main Belt asteroids, comets, Trojans, and Centaurs. By the end of survey operations in 2011 February, NEOWISE identified over 157,000 asteroids, including more than 500 NEOs and ~120 comets. The NEOWISE data set will enable a panoply of new scientific investigations.
771 citations
TL;DR: The Yarkovsky and YORP effects are thermal radiation forces and torques that cause small objects to undergo semimajor axis drift and spin vector modifications, respectively, as a function of their spin, orbit, and material properties as discussed by the authors.
Abstract: The Yarkovsky and YORP (Yarkovsky-O’Keefe-Radzievskii-Paddack) effects are thermal radiation forces and torques that cause small objects to undergo semimajor axis drift and spin vector modifications, respectively, as a function of their spin, orbit, and material properties. These mechanisms help to (a) deliver asteroids (and meteoroids) with diameter D < 40 km from their source locations in the main belt to chaotic resonance zones capable of transporting this material to Earth-crossing orbits; (b) disperse asteroid families, with drifting bodies jumping or becoming trapped in mean-motion and secular resonances within the main belt; (c) modify the rotation rates and obliquities of D < 40 km asteroids; and (d ) allow asteroids to enter into spin-orbit resonances, which affect the evolution of their spin vectors and feedback into the Yarkovsky-driven semimajor axis evolution. Accordingly, we suggest that nongravitational forces should now be considered as important as collisions and gravitational perturbations to our overall understanding of asteroid evolution.
661 citations
TL;DR: The PACS Evolutionary Probe (PEP) guaranteed time key program as discussed by the authors has been used in the entire set of Herschel surveys, and the field selection that includes popular multi-wavelength fields such as GOODS, COSMOS, Lockman Hole, ECDFS, and EGS.
Abstract: Deep far-infrared photometric surveys studying galaxy evolution and the nature of the cosmic infrared background are a key strength of the Herschel mission. We describe the scientific motivation for the PACS Evolutionary Probe (PEP) guaranteed time key program and its role within the entire set of Herschel surveys, and the field selection that includes popular multiwavelength fields such as GOODS, COSMOS, Lockman Hole, ECDFS, and EGS. We provide an account of the observing strategies and data reduction methods used. An overview of first science results illustrates the potential of PEP in providing calorimetric star formation rates for high-redshift galaxy populations, thus testing and superseding previous extrapolations from other wavelengths, and enabling a wide range of galaxy evolution studies.
541 citations
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TL;DR: DeMeo et al. as mentioned in this paper presented a review of the current knowledge of the density of small bodies and compared with meteorite density, allowing to estimate the macroporosity (i.e., amount of voids) within these bodies.
522 citations