arXiv subjects

Valerio Carruba

Publications and source records attributed to Valerio Carruba.

16 recordsLinked to original sources

arXiv2025

A catalog of near-IR absolute magnitudes of Solar System small bodies

Context. Phase curves of small bodies are useful tools to obtain their absolute magnitudes and phase coefficients. The former relates to the object's apparent brightness, while the latter relates to how the light interacts with the surface. Data from multi-wavelength photometric surveys, which usually serendipitously observe small bodies, are becoming the cornerstone of large statistical studies of the Solar System. Nevertheless, to our knowledge, all studies have been carried out in visible wavelengths. Aims. We aim to provide the first catalog of absolute magnitudes in near-infrared filters (Y, J, H, and K). We will study the applicability of a non-linear model to these data and compare it with a simple linear model. Methods. We compute the absolute magnitudes using two photometric models: the HG* 12 and the linear model. We employ a combination of Bayesian inference and Monte Carlo sampling to calculate the probability distributions of the absolute magnitudes and their corresponding phase coefficients. We use the combination of four near-infrared photometric catalogs to create our input database. Results. We produced the first catalog of near-infrared magnitudes. We obtained absolute magnitudes for over 10 000 objects (with at least one absolute magnitude measured), with about 180 objects having four absolute magnitudes. We confirmed that a linear model that fits the phase curves produces accurate results. Since a linear behavior well describes the curves, fitting to a restricted phase angle range (in particular, larger than 9.5 deg) does not substantially affect the results. Finally, we also detect a phase-coloring effect in the near-infrared, as observed in visible wavelengths for asteroids and trans-Neptunian objects.

astro-ph.EP↗

arXiv2023

Main belt asteroids taxonomical information from Dark Energy Survey data

While proper orbital elements are currently available for more than 1 million asteroids, taxonomical information is still lagging behind. Surveys like SDSS-MOC4 provided preliminary information for more than 100,000 objects, but many asteroids still lack even a basic taxonomy. In this study, we use Dark Energy Survey (DES) data to provide new information on asteroid physical properties. By cross-correlating the new DES database with other databases, we investigate how asteroid taxonomy is reflected in DES data. While the resolution of DES data is not sufficient to distinguish between different asteroid taxonomies within the complexes, except for V-type objects, it can provide information on whether an asteroid belongs to the C- or S-complex. Here, machine learning methods optimized through the use of genetic algorithms were used to predict the labels of more than 68,000 asteroids with no prior taxonomic information. Using a high-quality, limited set of asteroids with data on $gri$ slopes and $i-z$ colors, we detected 409 new possible V-type asteroids. Their orbital distribution is highly consistent with that of other known V-type objects.

astro-ph.EP↗

arXiv2022

Optimization of Artificial Neural Networks models applied to the identification of images of asteroids' resonant arguments

The asteroidal main belt is crossed by a web of mean-motion and secular resonances, that occur when there is a commensurability between fundamental frequencies of the asteroids and planets. Traditionally, these objects were identified by visual inspection of the time evolution of their resonant argument, which is a combination of orbital elements of the asteroid and the perturbing planet(s). Since the population of asteroids affected by these resonances is, in some cases, of the order of several thousand, this has become a taxing task for a human observer. Recent works used Convolutional Neural Networks (CNN) models to perform such task automatically. In this work, we compare the outcome of such models with those of some of the most advanced and publicly available CNN architectures, like the VGG, Inception and ResNet. The performance of such models is first tested and optimized for overfitting issues, using validation sets and a series of regularization techniques like data augmentation, dropout, and batch normalization. The three best-performing models were then used to predict the labels of larger testing databases containing thousands of images. The VGG model, with and without regularizations, proved to be the most efficient method to predict labels of large datasets. Since the Vera C. Rubin observatory is likely to discover up to four million new asteroids in the next few years, the use of these models might become quite valuable to identify populations of resonant minor bodies.

astro-ph.EP↗

arXiv2022

Identifying the population of stable ${\nu}_6$ resonant asteroids using large databases

Large observational surveys, like those that will be conducted at the Vera C. Rubin Observatory, are expected to discover up to one million new asteroids in the first year of operation. This will more than double the database of known asteroids. New methods and techniques will be needed to handle the large influx of data. Here, we tested some of these new methods by studying the population of asteroids on stable orbits inside the ${\nu}_6$ secular resonance. This resonance is one of the strongest mechanisms for destabilizing the orbits of main-belt bodies and producing Near-Earth Asteroids (NEAs). Yet, stable orbital configurations where the asteroid pericenter is either aligned or anti-aligned with that of Saturn exist inside the resonance. The population of stable ${\nu}_6$ resonators is now the largest population of asteroids in stable orbits inside a secular resonance. Here we obtained the largest sample of asteroids' proper elements ever used for this problem. Clustering methods and the use of machine learning algorithms permitted the identification of the known asteroid families crossed by the ${\nu}_6$ resonance and of two entirely new groups: the Tiffanykapler and the 138605 QW177 families. The Tiffanykapler family is the first young asteroid family ever found in a linear secular resonance, with an age of $3.0\pm1.2$ Myr and an ejection velocity field parameter of $V_{EJ} = 15^{+6}_{-3}$ m/s. We identify a population of high-eccentricity objects around the Tina family that may be the first example of an asteroid family "resonant halo".

astro-ph.EP↗

arXiv2021

Probabilistic modeling of asteroid diameters from Gaia DR2 errors

The Gaia Data Release 2 provides precise astrometry for nearly 1.5 billion sources across the entire sky, including several thousand asteroids. In this work, we provide evidence that reasonably large asteroids (diameter $>$ 20 km) have high correlations with Gaia relative flux uncertainties and systematic right ascension errors. We further capture these correlations using a logistic Bayesian additive regression tree model. We compile a small list of probable large asteroids that can be targeted for direct diameter measurements and shape reconstruction.

astro-ph.EP↗

arXiv2020

Analysis of the Karma asteroid family

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.

astro-ph.EP↗

arXiv2017

Detection of the Yarkovsky effect for C-type asteroids in the Veritas family

The age of a young asteroid family can be determined by tracking the orbits of family members backward in time and showing that they converge at some time in the past. Here we consider the Veritas family. We find that the membership of the Veritas family increased enormously since the last detailed analysis of the family. Using backward integration, we confirm the convergence of nodal longitudes $Ω$, and, for the first time, also obtain a simultaneous convergence of pericenter longitudes $\varpi$. The Veritas family is found to be $8.23^{+0.37}_{-0.31}$~Myr old. To obtain a tight convergence of $Ω$ and $\varpi$, as expected from low ejection speeds of fragments, the Yarkovsky effect needs to be included in the modeling of the past orbital histories of Veritas family members. Using this method, we compute the Yarkovsky semi-major axis drift rates, ${\rm d}a/{\rm d}t$, for 274 member asteroids. The distribution of ${\rm d}a/{\rm d}t$ values is consistent with a population of C-type objects with low densities and low thermal conductivities. The accuracy of individual ${\rm d}a/{\rm d}t$ measurements is limited by the effect of close encounters of member asteroids to (1) Ceres and other massive asteroids, which cannot be evaluated with confidence.

astro-ph.EP↗

arXiv2017

Scattering V-type asteroids during the giant planets instability: A step for Jupiter, a leap for basalt

V-type asteroids are a taxonomic class whose surface is associated to a basaltic composition. The only known source of V-type asteroids in the Main Asteroid Belt is (4) Vesta, that is located in the inner part of the belt. However, many V-type asteroids cannot be dynamically linked to Vesta., in particular, those asteroids located in the middle and outer parts of the Belt. Previous works have failed to find mechanisms to transport V-type asteroids from the inner to the middle and outer belt. In this work we propose a dynamical mechanism that could have acted on primordial asteroid families. We consider a model of the giant planets migration known as the jumping Jupiter model with five planets. Our study is focused on the period of 10 Myr that encompasses the instability phase of the giant planets. We show that, for different hypothetical Vesta-like paleo-families in the inner belt, the perturbations caused by the ice giant that is scattered into the asteroid belt before being ejected from the solar system, are able to scatter V-type asteroids to the middle and outer belt. Based on the orbital distribution of V-type candidates identified from the Sloan Digital Sky Survey and the VISTA Survey colours, we show that this mechanism is efficient enough provided that the hypothetical paleo-family originated from a 100 to 500 km crater excavated on the surface of (4) Vesta. This mechanism is able to explain the currently observed V-type asteroids in the middle and outer belt, with the exception of (1459) Magnya.

astro-ph.EP↗

arXiv2016

The dynamical environment of asteroid 21 Lutetia according to different internal models

One of the most accurate models currently used to represent the gravity field of irregular bodies is the polyhedral approach. In this model, the mass of the body is assumed to be homogeneous, which may not be true for a real object. The main goal of the present paper is to study the dynamical effects induced by three different internal structures (uniform, three- and four-layers) of asteroid (21) Lutetia, an object that recent results from space probe suggest being at least partially differentiated. The Mascon gravity approach used in the present work, consists of dividing each tetrahedron into eight parts to calculate the gravitational field around the asteroid. The zero-velocity curves show that the greatest displacement of the equilibrium points occurs in the position of the E4 point for the four-layers structure and the smallest one occurs in the position of the E3 point for the three-layers structure. Moreover, stability against impact shows that the planar limit gets slightly closer to the body with the four-layered structure. We then investigated the stability of orbital motion in the equatorial plane of (21) Lutetia and propose numerical stability criteria to map the region of stable motions. Layered structures could stabilize orbits that were unstable in the homogeneous model.

astro-ph.EP↗

arXiv2016

Detection of the YORP Effect for Small Asteroids in the Karin Cluster

The Karin cluster is a young asteroid family thought to have formed only $\simeq 5.75$~My ago. The young age can be demonstrated by numerically integrating the orbits of Karin cluster members backward in time and showing the convergence of the perihelion and nodal longitudes (as well as other orbital elements). Previous work has pointed out that the convergence is not ideal if the backward integration only accounts for the gravitational perturbations from the Solar System planets. It improves when the thermal radiation force known as the Yarkovsky effect it is accounted for. This argument can be used to estimate the spin obliquities of the Karin cluster members. Here we take advantage of the fast growing membership of the Karin cluster and show that the obliquity distribution of diameter $D\simeq 1-2$ km Karin asteroids is bimodal, as expected if the YORP effect acted to move obliquities toward the extreme values ($0^\circ$ or $180^\circ$). The measured magnitude of the effect is consistent with the standard YORP model. The surface thermal conductivity is inferred to be $0.07$-0.2 W m$^{-1}$ K$^{-1}$ (thermal inertia $\simeq 300-500$ J m$^{-2}$ K$^{-1}$s$^{-1/2}$). We find that the strength of the YORP effect is roughly $\simeq 0.7$ of the nominal strength obtained for a collection of random Gaussian spheroids. These results are consistent with a surface composed of rough, rocky regolith. The obliquity values predicted here for 480 members of the Karin cluster can be validated by the light-curve inversion method.

astro-ph.EP↗

arXiv2016

Characterizing the original ejection velocity field of the Koronis family

An asteroid family forms as a result of a collision between an impactor and a parent body. The fragments with ejection speeds higher than the escape velocity from the parent body can escape its gravitational pull. The cloud of escaping debris can be identified by the proximity of orbits in proper element, or frequency, domains. Obtaining estimates of the original ejection speed can provide valuable constraints on the physical processes occurring during collision, and used to calibrate impact simulations. Unfortunately, proper elements of asteroids families are modified by gravitational and non-gravitational effects, such as resonant dynamics, encounters with massive bodies, and the Yarkovsky effect, such that information on the original ejection speeds is often lost, especially for older, more evolved families. It has been recently suggested that the distribution in proper inclination of the Koronis family may have not been significantly perturbed by local dynamics, and that information on the component of the ejection velocity that is perpendicular to the orbital plane ($v_W$), may still be available, at least in part. In this work we estimate the magnitude of the original ejection velocity speeds of Koronis members using the observed distribution in proper eccentricity and inclination, and accounting for the spread caused by dynamical effects. Our results show that i) the spread in the original ejection speeds is, to within a 15% error, inversely proportional to the fragment size, and ii) the minimum ejection velocity is of the order of 50 m/s, with larger values possible depending on the orbital configuration at the break-up.

astro-ph.EP↗

arXiv2016

Constraints on the original ejection velocity fields of asteroid families

Asteroid families form as a result of large-scale collisions among main belt asteroids. The orbital distribution of fragments after a family-forming impact could inform us about their ejection velocities. Unfortunately, however, orbits dynamically evolve by a number of effects, including the Yarkovsky drift, chaotic diffusion, and gravitational encounters with massive asteroids, such that it is difficult to infer the ejection velocities eons after each family's formation. Here we analyze the inclination distribution of asteroid families, because proper inclination can remain constant over long time intervals, and could help us to understand the distribution of the component of the ejection velocity that is perpendicular to the orbital plane ($v_{W}$). From modeling the initial breakup, we find that the distribution of $v_{W}$ of the fragments, which manage to escape the parent body's gravity, should be more peaked than a Gaussian distribution (i.e., be leptokurtic) even if the initial distribution was Gaussian. We surveyed known asteroid families for signs of a peaked distribution of $v_{W}$ using a statistical measure of the distribution peakedness or flatness known as kurtosis. We identified eight families whose $v_{W}$ distribution is significantly leptokurtic. These cases (e.g. the Koronis family) are located in dynamically quiet regions of the main belt, where, presumably, the initial distribution of $v_{W}$ was not modified by subsequent orbital evolution. We suggest that, in these cases, the inclination distribution can be used to obtain interesting information about the original ejection velocity field.

astro-ph.EP↗

arXiv2015

On the Erigone family and the $z_2$ secular resonance

The Erigone family is a C-type group in the inner main belt. Its age has been estimated by several researchers to be less then 300 My, so it is a relatively young cluster. Yarko-YORP Monte Carlo methods to study the chronology of the Erigone family confirm results obtained by other groups. The Erigone family, however, is also characterized by its interaction with the $z_2$ secular resonance. While less than 15% of its members are currently in librating states of this resonance, the number of objects, members of the dynamical group, in resonant states is high enough to allow to use the study of dynamics inside the $z_2$ resonance to set constraints on the family age. Like the $ν_{6}$ and $z_1$ secular resonances, the $z_2$ resonance is characterized by one stable equilibrium point at $σ= 180^{\circ}$ in the $z_2$ resonance plane $(σ, \frac{dσ}{dt})$, where $σ$ is the resonant angle of the $z_2$ resonance. Diffusion in this plane occurs on timescales of $\simeq 12$ My, which sets a lower limit on the Erigone family age. Finally, the minimum time needed to reach a steady-state population of $z_2$ librators is about 90 My, which allows to impose another, independent constraint on the group age.

astro-ph.EP↗

arXiv2015

Dynamical evolution of the Cybele asteroids

The Cybele region, located between the 2J:-1A and 5J:-3A mean-motion resonances, is adjacent and exterior to the asteroid main belt. An increasing density of three-body resonances makes the region between the Cybele and Hilda populations dynamically unstable, so that the Cybele zone could be considered the last outpost of an extended main belt. The presence of binary asteroids with large primaries and small secondaries suggested that asteroid families should be found in this region, but only relatively recently the first dynamical groups were identified in this area. Among these, the Sylvia group has been proposed to be one of the oldest families in the extended main belt. In this work we identify families in the Cybele region in the context of the local dynamics and non-gravitational forces such as the Yarkovsky and stochastic YORP effects. We confirm the detection of the new Helga group at $\simeq$3.65~AU, that could extend the outer boundary of the Cybele region up to the 5J:-3A mean-motion resonance. We obtain age estimates for the four families, Sylvia, Huberta, Ulla and Helga, currently detectable in the Cybele region, using Monte Carlo methods that include the effects of stochastic YORP and variability of the Solar luminosity. The Sylvia family should be $T = 1220 \pm 40$ Myr old, with a possible older secondary solution. Any collisional Cybele group formed prior to the late heavy bombardment would have been most likely completely dispersed in the jumping Jupiter scenario of planetary migration.

astro-ph.EP↗

arXiv2014

Dynamical evolution of V-type photometric candidates in the outer Main-belt

V-type asteroids, characterized by two absorption bands at 1.0 and 2.0 $μm$, are usually thought to be portions of the crust of differentiated or partially differentiated bodies. Most V-type asteroids are found in the inner main belt and are thought to be current or past members of the Vesta dynamical family. Recently, several V-type photometric candidates have been identified in the central and outer main belt. While the dynamical evolution of V-type photometric candidates in the central main belt has been recently investigated, less attention has been given to the orbital evolution of basaltic material in the outer main belt as a whole. Here we identify known and new V-type photometric candidates in this region, and study their orbital evolution under the effect of gravitational and non-gravitational forces. A scenario in which a minimum of three local sources, possibly associated with the parent bodies of (349) Dembowska, (221) Eos, and (1459) Magnya, could in principle explain the current orbital distribution of V-type photometric candidates in the region.

astro-ph.EP↗

arXiv2005

On the V-type asteroids outside the Vesta family. I. Interplay of nonlinear secular resonances and the Yarkovsky effect: the cases of 956 Elisa and 809 Lundia

Among the largest objects in the main belt, asteroid 4 Vesta is unique in showing a basaltic crust. It is also the biggest member of the Vesta family, which is supposed to originate from a large cratering event about 1 Gyr ago (Marzari et al. 1996). Most of the members of the Vesta family for which a spectral classification is available show a V-type spectra. Before the discovery of 1459 Magnya (Lazzaro et al. 2000) and of several V-type NEA (Xu 1995), all the known V-type asteroids were members of the Vesta family. Recently two V-type asteroids, 809 Lundia and 956 Elisa, (Florczak et al. 2002) have been discovered well outside the limits of the family, near the Flora family. We currently know 22 V-type asteroids outside the family, in the inner asteroid belt. In this work we investigate the possibility that these objects are former family members that migrated to their current positions via the interplay of Yarkovsky effect and nonlinear secular resonances. The main dynamical feature of 956 Elisa and 809 Lundia is that they are currently inside the 2(g-g6)+s-s6 (z2 by Milani and Knezevic, 1993) secular resonance. Our investigations show that members of the Vesta dynamical family may drift in three-body and weak secular resonances until they are captured in the strong z2 secular resonance. Only asteroids with diameters larger than 16 km can remain in one of the three-body or secular resonances long enough to reach the region of the z2 resonance. This two-step mechanism of capture into the z2 resonance could explain: i) the current resonant orbits of 956 Elisa and 809 Lundia, ii) why their size is significantly larger than that of the typical member of the Vesta family, and iii) provide a lower limit on the Vesta family age.

astro-ph↗