scholarly journals What we know about Families of Asteroids

1989 ◽  
Vol 8 ◽  
pp. 273-279
Author(s):  
V. Zappala’
Keyword(s):  
Family Members ◽  
Parent Body ◽  
Classification Methods ◽  
Hypervelocity Impacts ◽  
Mass Distributions ◽  
Proper Elements ◽  
The Family ◽  
Families Of Asteroids ◽  
Asteroid Families ◽  
Degree Of Fragmentation

AbstractAsteroid families are considered for the most to represent fragments of collisional breakup of precursor bodies. If true, this offers the unique possibility to examine the interiors of large bodies and to study the processes of collision on a scale much larger than can be done in laboratory. Indeed, the general features of the mass distributions and of the ejection velocities of the family members can be interpreted in terms of collisional disruption of a parent body followed by self-gravitational reaccumulation on the largest remnant. However, several problems remain open: a) the degree of fragmentation in real families is generally lower than that observed for experimental targets; b) the relative velocities computed including also proper eccentricity and inclination differences are higher by about a factor 4 than those derived from semiaxes differences only; c) only very few of the presently proposed families have distributions of inferred mineralogies consistent with cosmochemistry. Further studies are needed, including better proper elements computation, classification methods, and new investigations on the physics of hypervelocity impacts.

Spin clusters inside four young asteroid groups

2020 ◽  
Vol 493 (2) ◽  
pp. 2556-2567
Author(s):  
V Carruba ◽  
L G M Ramos ◽  
F Spoto
Keyword(s):  
Numerical Simulations ◽  
Transition Region ◽  
Semimajor Axis ◽  
Family Members ◽  
Proper Elements ◽  
The Family ◽  
Induced Fission ◽  
Spin Clusters ◽  
Spin Pairs ◽  
Asteroid Families

ABSTRACT Asteroid groups may either form because of collisions or because of spin induced fission. Recently it has been shown that young spin clusters tend to form more frequently in young collisional families than in older groups. Here, we study the occurrence of spin clusters inside four very recently identified asteroid groups: the (525) Adelaide, (2258) Viipuri, (6142) Tantawi, and (18429) (1994 AO1) groups. Using combinations of techniques based on backward numerical simulations, we identify four spin pairs among the family members. All groups have fractions of observed spin clusters well above 5 per cent, so confirming an observed trend for other young asteroid groups. The (2258) Viipuri and (18429) (1994 AO1) groups are compatible with an origin as a spin clusters themselves, and could be other occurrences of cascade spin clusters, as recently detected in other asteroid groups. Finally, the separation between collisional asteroid families and spin clusters in domains of dispersion of proper semimajor axis, σa, versus age seems to be more complex than previously thought. While spin clusters tend to be much more compact in proper elements than collisional families, there appears to be a transition region in σa where both the groups be found.

scholarly journals Extended Families in the Main Belt and in the Trojan Swarms

2005 ◽  
Vol 13 ◽  
pp. 758-758 ◽  
Author(s):  
Zoran Knezevic ◽  
Andrea Milani
Keyword(s):  
Hubble Space Telescope ◽  
Family Members ◽  
Mean Motion Resonances ◽  
Size Dependent ◽  
Proper Elements ◽  
Chaotic Diffusion ◽  
Large Spread ◽  
The Family ◽  
Long Time ◽  
Asteroid Families

The availability of highly accurate synthetic proper elements for a large number of asteroids made possible detailed studies of the structure of asteroid families. The entire region of the Vesta family is dominated by bodies with D < 7 km. The large spread of family members appears to be primarily due to Yarkovsky mobility, a strongly size-dependent. The proper elements of the asteroids the region (except close to mean motion resonances) are stable over very long time spans; thus chaotic diffusion could not play a significant role. The total volume of the family members with diameter less than 7 km amounts approximately to 6 x 104 cubic km, the volume of a crater with 100 km diameter and average depth 7 km. If the albedo feature, visible in the Hubble Space Telescope images, is really a crater its volume could be even larger. Thanks to the recently computed catalogs of proper elements for 1167 trojans, there are now confirmed dynamical families in the trojan swarms. This allows to begin to study the collisional evolution with constraints from observations.

scholarly journals Machine-learning identification of asteroid groups

2019 ◽  
Vol 488 (1) ◽  
pp. 1377-1386 ◽  
Author(s):  
V Carruba ◽  
S Aljbaae ◽  
A Lucchini
Keyword(s):  
Machine Learning ◽  
Hierarchical Clustering ◽  
Clustering Algorithms ◽  
Family Members ◽  
Parent Body ◽  
Clustering Methods ◽  
New Family ◽  
Hierarchical Clustering Methods ◽  
Rotational Failure ◽  
Asteroid Families

ABSTRACT Asteroid families are groups of asteroids that share a common origin. They can be the outcome of a collision or be the result of the rotational failure of a parent body or its satellites. Collisional asteroid families have been identified for several decades using hierarchical clustering methods (HCMs) in proper elements domains. In this method, the distance of an asteroid from a reference body is computed, and, if it is less than a critical value, the asteroid is added to the family list. The process is then repeated with the new object as a reference, until no new family members are found. Recently, new machine-learning clustering algorithms have been introduced for the purpose of cluster classification. Here, we apply supervised-learning hierarchical clustering algorithms for the purpose of asteroid families identification. The accuracy, precision, and recall values of results obtained with the new method, when compared with classical HCM, show that this approach is able to found family members with an accuracy above 89.5 per cent, and that all asteroid previously identified as family members by traditional methods are consistently retrieved. Values of the areas under the curve coefficients below Receiver Operating Characteristic curves are also optimal, with values consistently above 85 per cent. Overall, we identify 6 new families and 13 new clumps in regions where the method can be applied that appear to be consistent and homogeneous in terms of physical and taxonomic properties. Machine-learning clustering algorithms can, therefore, be very efficient and fast tools for the problem of asteroid family identification.

scholarly journals Asteroid Family Identification: History and State of the Art

2015 ◽  
Vol 10 (S318) ◽  
pp. 16-27 ◽  
Author(s):  
Zoran Knežević
Keyword(s):  
State Of The Art ◽  
The State ◽  
Classification Methods ◽  
Data Set ◽  
The Third ◽  
Proper Elements ◽  
The Future ◽  
History Of ◽  
Asteroid Families ◽  
Collisional Evolution

AbstractThe history of asteroid families, from their discovery back in 1918, until the present time, is briefly reviewed. Two threads have been followed: on the development of the theories of asteroid motion and the computation of proper elements, and on the methods of classification themselves. Three distinct periods can be distinguished: the first one until mid-1930s, devoted to discovery and first attempts towards understanding of the properties of families; the second one, until early 1980s, characterized by a growing understanding of their importance as key evidence of the collisional evolution; the third one, characterized by an explosion of work and results, comprises the contemporary era. An assessment is given of the state-of-the-art and possible directions for the future effort, focusing on the dynamical studies, and on improvements of classification methods to cope with ever increasing data set.

scholarly journals Physical and dynamical characterization of the Euphrosyne asteroid family

2020 ◽  
Vol 643 ◽  
pp. A38
Author(s):  
B. Yang ◽  
J. Hanuš ◽  
M. Brož ◽  
O. Chrenko ◽  
M. Willman ◽  
...  
Keyword(s):  
Family Members ◽  
Orbital Evolution ◽  
Parent Body ◽  
Element Space ◽  
Infrared Telescope ◽  
The Family ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Telescope Facility ◽  
Homogeneous Composition

Aims. The Euphrosyne asteroid family occupies a unique zone in orbital element space around 3.15 au and may be an important source of the low-albedo near-Earth objects. The parent body of this family may have been one of the planetesimals that delivered water and organic materials onto the growing terrestrial planets. We aim to characterize the compositional properties as well as the dynamical properties of the family. Methods. We performed a systematic study to characterize the physical properties of the Euphrosyne family members via low-resolution spectroscopy using the NASA Infrared Telescope Facility. In addition, we performed smoothed-particle hydrodynamics (SPH) simulations and N-body simulations to investigate the collisional origin, determine a realistic velocity field, study the orbital evolution, and constrain the age of the Euphrosyne family. Results. Our spectroscopy survey shows that the family members exhibit a tight taxonomic distribution, suggesting a homogeneous composition of the parent body. Our SPH simulations are consistent with the Euphrosyne family having formed via a reaccumulation process instead of a cratering event. Finally, our N-body simulations indicate that the age of the family is 280−80+180 Myr, which is younger than previous estimates.

scholarly journals Reconnecting groups of space debris to their parent body through proper elements

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alessandra Celletti ◽  
Giuseppe Pucacco ◽  
Tudor Vartolomei
Keyword(s):  
Space Debris ◽  
Parent Body ◽  
Statistical Data Analysis ◽  
Proper Elements ◽  
Dynamical Features ◽  
Break Up ◽  
Osculating Elements ◽  
Original Configuration ◽  
Over Time ◽  
Asteroid Families

AbstractSatellite collisions or fragmentations generate a huge number of space debris; over time, the fragments might get dispersed, making it difficult to associate them to the configuration at break-up. In this work, we present a procedure to back-trace the debris, reconnecting them to their original configuration. To this end, we compute the proper elements, namely dynamical quantities which stay nearly constant over time. While the osculating elements might spread and lose connection with the values at break-up, the proper elements, which have been already successfully used to identify asteroid families, retain the dynamical features of the original configuration. We show the efficacy of the procedure, based on a hierarchical implementation of perturbation theory, by analyzing the following four different case studies associated to satellites that underwent a catastrophic event: Ariane 44lp, Atlas V Centaur, CZ-3, Titan IIIc Transtage. The link between (initial and final) osculating and proper elements is evaluated through tools of statistical data analysis. The results show that proper elements allow one to reconnect the fragments to their parent body.

scholarly journals Asteroid cratering families: recognition and collisional interpretation

2019 ◽  
Vol 622 ◽  
pp. A47 ◽  
Author(s):  
A. Milani ◽  
Z. Knežević ◽  
F. Spoto ◽  
P. Paolicchi
Keyword(s):  
Dynamical Evolution ◽  
Parent Body ◽  
Element Space ◽  
Secular Resonance ◽  
Proper Elements ◽  
The Family ◽  
New Interpretation ◽  
Fragmentation Type ◽  
Definition Of ◽  
Quantitative Definition

Aims. We continue our investigation of the bulk properties of asteroid dynamical families identified using only asteroid proper elements to provide plausible collisional interpretations. We focus on cratering families consisting of a substantial parent body and many small fragments. Methods. We propose a quantitative definition of cratering families based on the fraction in volume of the fragments with respect to the parent body; fragmentation families are above this empirical boundary. We assess the compositional homogeneity of the families and their shape in proper element space by computing the differences of the proper elements of the fragments with respect to the ones of the major body, looking for anomalous asymmetries produced either by post-formation dynamical evolution, or by multiple collisional/cratering events, or by a failure of the hierarchical clustering method (HCM) for family identification. Results. We identified a total of 25 dynamical families with more than 100 members ranging from moderate to heavy cratering. For three families (4, 15 and 283) we confirm the occurrence of two separate cratering events, while family (569) Misa is a mixed case, with one cratering event and one fragmentation event. The case of family 3 remains dubious, in that there could be either one or two collisions. For family 20, we propose a double collision origin, not previously identified. In four cases (31, 480, 163 and 179) we performed a dedicated search for dynamical resonant transport mechanisms that could have substantially changed the shape of the family. By using a new synthetic method for computation of secular frequencies, we found possible solutions for families 31, 480, and 163, but not for family 179, for which we propose a new interpretation, based on a secular resonance contaminating this family: the family of 179 should be split into two separate clusters, one containing (179) itself and the other, family (9506) Telramund, of fragmentation type, for which we have computed an age.

scholarly journals Analysis of the Karma asteroid family

2020 ◽  
Vol 501 (1) ◽  
pp. 356-366
Author(s):  
Debora Pavela ◽  
Bojan Novaković ◽  
Valerio Carruba ◽  
Viktor Radović
Keyword(s):  
Numerical Simulations ◽  
Family Members ◽  
Dynamical Evolution ◽  
Absolute Magnitude ◽  
Parent Body ◽  
Outer Edge ◽  
Middle Part ◽  
Near Earth Space ◽  
The Family ◽  
Original Family

ABSTRACT The Karma asteroid family is a group of primitive asteroids in the middle part of the main belt, just at the outer edge of the 3J:1A mean-motion resonance. We obtained the list of the family members with 317 asteroids, and estimated that it was formed by the catastrophic disruption of a parent body that was between 34 and 41 km in diameter. Based on the V-shape method, age of the Karma family is estimated to be about 137 Myr. A detailed dynamical map of the region combined with numerical simulations allowed us to reconstruct the long-term dynamical evolution of the family, and to identify the mechanisms responsible for this evolution. The numerical simulations successfully reproduced the main features in the orbital distribution of the family members but also showed that some regions of the Karma family could be missing. A more detailed analysis revealed that these regions likely consist of very dark objects, fainter than absolute magnitude H = 17, that have not yet been detected. Based on the obtained results, we concluded that magnitude–frequency distribution of family members up to H = 16 mag is neither affected by dynamical erosion nor observational incompleteness, and therefore represents the result of collisional grinding of the original family population. Finally, we found that the Karma family have been supplying some asteroids to the near-Earth region via the 3J:1A resonance. Currently, there should about 10 family members larger than 1 km in diameter, orbiting in the near-Earth space.

scholarly journals Excluding interlopers from asteroid families

2014 ◽  
Vol 9 (S310) ◽  
pp. 174-175
Author(s):  
Viktor Radović ◽  
Bojan Novaković
Keyword(s):  
Family Members ◽  
New Approach ◽  
The Family ◽  
Asteroid Families

AbstractTo study an asteroid family it is crucial to determine reliably the list of its members, i.e. to reduce the number of interlopers as much as possible. However, as the number of known asteroids increases fast it becomes more and more difficult to obtain robust list of members of an asteroid family. To cope with these challenges we are proposing a new approach that may help to significantly reduce presence of interlopers among the family members.

scholarly journals Color study of asteroid families within the MOVIS catalog

2018 ◽  
Vol 617 ◽  
pp. A72 ◽  
Author(s):  
David Morate ◽  
Javier Licandro ◽  
Marcel Popescu ◽  
Julia de León
Keyword(s):  
Parameter Space ◽  
Near Infrared ◽  
Statistical Tests ◽  
Parent Body ◽  
Family Data ◽  
Cluster Distribution ◽  
The Family ◽  
The One ◽  
Compositional Diversity ◽  
Asteroid Families

The aim of this work is to study the compositional diversity of asteroid families based on their near-infrared colors, using the data within the MOVIS catalog. As of 2017, this catalog presents data for 53 436 asteroids observed in at least two near-infrared filters (Y, J, H, or Ks). Among these asteroids, we find information for 6299 belonging to collisional families with both Y −J and J−Ks colors defined. The work presented here complements the data from SDSS and NEOWISE, and allows a detailed description of the overall composition of asteroid families. We derived a near-infrared parameter, the ML*, that allows us to distinguish between four generic compositions: two different primitive groups (P1 and P2), a rocky population, and basaltic asteroids. We conducted statistical tests comparing the families in the MOVIS catalog with the theoretical distributions derived from our ML* in order to classify them according to the above-mentioned groups. We also studied the background populations in order to check how similar they are to their associated families. Finally, we used this parameter in combination with NEOWISE and SDSS to check for possible bimodalities in the data. We found 43 families with ML*err < 0.071 and with at least 8 asteroids observed: 5 classified as P1, 10 classified as P2, 19 families associated with the rocky population, and 9 families that were not linked to any of the previous populations. In these cases, we compared our samples with different combinations of these theoretical distributions to find the one that best fits the family data. We also show, using the data from MOVIS and NEOWISE, that the Bapistina family presents a two-cluster distribution in the near-infrared albedo vs. ML* parameter space that might be related to a common differentiated parent body. Finally, we show that the backgrounds we defined seem to be linked to their associated families.

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