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We explore the hypothesis that the Eureka family of sub-km asteroids in the L5 region of Mars could have formed in a collision. We estimate the size distribution index from available information on family members; model the orbital dispersion of collisional fragments; and carry out a formal calculation of the collisional lifetime as a function of size. We find that, as initially conjectured by Rivkin...
In this work we have estimated 10 collisional ages of 9 families for which for different reasons our previous attempts failed. In general, these are difficult cases that required dedicated effort, such as a new family classifications for asteroids in mean motion resonances, in particular the 1/1 and 2/1 with Jupiter, as well as a revision of the classification inside the 3/2 resonance. Of the families...
Being intermediate between a regular triaxial ellipsoid shape and a more complex convex shape, the so-called “cellinoid” shape model consists of eight octants of eight ellipsoids with the constraint that neighbouring octants share two common axes. The resulting variety of possible shapes, obtained at the cost of only three extra parameters to be added to models of regular ellipsoids, can be employed...
The number of asteroids with accurately determined orbits increases fast, and this increase is also accelerating. The catalogs of asteroid physical observations have also increased, although the number of objects is still smaller than in the orbital catalogs. Thus it becomes more and more challenging to perform, maintain and update a classification of asteroids into families. To cope with these challenges...
We present the results of our search for a dynamical family around the active Asteroid P/2012 F5 (Gibbs). By applying the hierarchical clustering method, we discover an extremely compact 9-body cluster associated with P/2012 F5. The statistical significance of this newly discovered Gibbs cluster is estimated to be >99.9%, strongly suggesting that its members share a common origin. The cluster is...
We present a new classification of families identified among the population of high-inclination asteroids. We computed synthetic proper elements for a sample of 18,560 numbered and multi-opposition objects having sine of proper inclination greater than 0.295. We considered three zones at different heliocentric distances (inner, intermediate and outer region) and used the standard approach based on...
We develop a three-parameter H, G 1 , G 2 magnitude phase function for asteroids starting from the current two-parameter H, G phase function. We describe stochastic optimization of the basis functions of the magnitude phase function based on a carefully chosen set of asteroid photometric observations covering the principal types of phase dependencies. We then illustrate the magnitude...
To try to understand the dynamical and collisional evolution of the Hungaria asteroids we have built a large catalog of accurate synthetic proper elements. Using the distribution of the Hungaria, in the spaces of proper elements and of proper frequencies, we can study the dynamical boundaries and the internal structure of the Hungaria region, both within a purely gravitational model and also showing...
We present new imaging polarimetric observations of two Main Belt asteroids, (234) Barbara and (387) Aquitania, taken in the first half of 2008 using the Dual-Beam Imaging Polarimeter on the University of Hawaii 2.2 m telescope, located on Mauna Kea, Hawaii. Barbara had been previously shown to exhibit a very unusual polarization-phase curve by [Cellino, A., Belskaya, I.N., Bendjoya, Ph., di Martino,...
New UBVRI polarimetric observations of ten asteroids, including space mission targets 1 Ceres and 21 Lutetia, are presented. These observations were obtained with the 1.25-m telescope of the Crimean Astrophysical Observatory and have been used to study the wavelength dependence of polarization for a sample of asteroids belonging to the M and low albedo classes. A more general analysis including also...
We show that the new ephemeris-space multiple-address-comparison (eMAC) method solves asteroid linking problems despite large parallaxes by applying the method to astrometric asteroid observation sets obtained nearly simultaneously with the Spitzer space telescope, the Canada–France–Hawaii Telescope (CFHT), and European Southern Observatory's Very Large Telescope (VLT). For main-belt asteroids, the...
The Very Large Telescope Interferometer (VLTI) of the European Southern Observatory (ESO) can be used to obtain direct determination of the sizes and the albedos of asteroids. We present results of the first attempt to carry out interferometric observations of asteroids with the Mid Infrared Interferometric Instrument (MIDI) at the VLTI. Our target was 1459 Magnya. This is the only V-type asteroid...
The near-Earth Asteroid 25143 Itokawa, the target of the Japanese space mission Hayabusa, was observed in June, 2004 with the Torino photopolarimeter attached at the 2.15 m telescope of the El Leoncito Observatory (Argentina). The degree of linear polarization in five colors was measured over a wide range of phase angles, between 40° and 80°. The data obtained are sufficient to derive an estimate...
We present the results of a campaign of spectroscopic observations of Jupiter Trojan asteroids. Thirty-four objects were observed during three runs in July and November 1998, and March 2002 using the Danish 1.54-m telescope at ESO. The covered spectral range was between 5000 and 9000 A. Our observations include objects belonging both L 4 to L 5 clouds. According to analyses of previous...
The first results of the observational program devoted to simultaneous investigation of asteroid polarimetric and photometric opposition phenomena are presented. UBVRI polarimetric and V-band photometric observations of the S-type Asteroid 20 Massalia and the E-type Asteroids 214 Aschera and 620 Drakonia were carried out in 1996-1999 down to phase angles of 0.08 o , 0.7 o , and 1.2...
The so-called Aten asteroids, evolving on orbits with semimajor axis a<1 AU and aphelion distance Q>0.983 AU, spend most of their time inside Earth's orbit. Currently, they account for about 7% of the observed near-Earth asteroid population and 13% of the Earth-crossing one. However, observational biases play against their discovery; thus the present number of Atens is probably severely underestimated...
We observed 44 Eunomia family members at ESO (European Southern Observatory) and at CASLEO (Complejo Astronomico El Leoncito) in the wavelength range of 4900-9200 A. We found 41 objects with the same characteristics: a maximum around λ=7500 A, and a reflectivity gradient spanning a continuous but limited range. Only 3 objects display featureless spectra similar to C-type asteroids, and these should...
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