Mario Melita

National Scientific and Technical Research Council | conicet · IAFE - Instituto de Astronomía y Física del Espacio

In this article we investigate the masses, orbital periods, semimajor axis, eccentricities and radii of the existing exoplanets by comparing the first and second digit probabilities with Benford laws’s predictions. It is found that the masses, orbital periods and semimajor axis conform to Benfordós law quite well, but radii fail. It is also investi...

Aims. The aim of this work is to develop a formalism for the study of the secular evolution of a binary system which includes interaction due to the tides that each body imparts on the other. We also consider the influence of the J 2 -related secular terms on the orbital evolution and the torque, caused by the triaxiality, on the rotational evoluti...

We aim to study the orbital and rotational evolution of binary system, formed by a rocky planet and its host star, near spin-orbit resonances, considering the tidal dissipation within both bodies in order to characterize the dynamical evolution with respect to the main features of the tidal evolution, i.e. synchronization, circularization and plana...

The discovery of ring systems around objects of the outer Solar System provides a strong motivation to apply theoretical models in order to better estimate their physical and orbital parameters, which can constrain scenarios for their origin. We review the criterion for maintaining apse-alignment across a ring and the balance between the energy inp...

The discovery of ring systems around objects of the outer Solar System provides a strong motivation to apply theoretical models in order to better estimate their physical and orbital parameters, which can constrain scenarios for their origin. We review the criterion for maintaining apse-alignment across a ring and the balance between the energy inp...

Context. The mid-transit times of an exoplanet may be nonperiodic. The variations in the timing of the transits with respect to a single period, that is, the transit timing variations (TTVs), can sometimes be attributed to perturbations by other exoplanets present in the system, which may or may not transit the star. Aims. Our aim is to compute the...

We report on time series photometry of the faint Neptune irregular satellite Neso. Observations in the V, R, and I pass-bands were performed in photometric conditions at the Cerro Paranal observatory using the instrument FORS2, in the night of July 15th, 2010. Astrometry and photometry derived from these observations are presented here. The time co...

The discovery that the centaur (10199) Chariklo possesses a ring system opens questions about their origin. We here asses the plausibility of different scenarios for the origin of the observed ring system. We first consider the possibility that the material of the ring originated in the disruption of a satellite that had reached a critical distance...

The aim of this paper is to contribute to the characterization of the general properties of the Long Period Comets (LPCs) family, and in particular to report on the dust environment of comet C/2009 P1 (Garradd). The comet was observed at two epochs pre-perihelion, at similar to 6 AU and at similar to 2.5 AU: broad-band images have been used to inve...

We present four new transit observations of the exoplanet WASP-28b observed between 2011 August and 2013 October. Employing another 11 transits available in the literature we compute new ephemeris and redetermine the physical parameters of the star and the exoplanet. Considering 3 yr of observations, we find no periodic transit timing variations (T...

In this work we present a system for autonomous discovery of asteroids, space trash and other moving objects. This system performs astronomical image data reduction based on an image processing pipeline. The processing steps of the pipeline include astrometric and photometric reduction, sequence alignment, moving object detection and astronomical a...

Most of the objects in the trans-Neptunian belt (TNb) and related populations move in prograde orbits with low eccentricity and inclination. However, the list of icy minor bodies moving in orbits with an inclination above 40 ◦ has increased in recent years. The origin of these bodies, and in particular of those objects in retrograde orbits, is not...

The surfaces of small bodies in the outer Solar System are rich in organic compounds and carbonaceous refractories mixed with ices and silicates. As made clear by dedicated laboratory experiments space weathering (e.g. energetic ion bombardment) can produce red colored materials starting from bright and spectrally flat ices. In a classical scenario...

We determined the light curves of two Jupiter Trojans. For (16070) 1999 RB101 we found periods of 52.80hs and for (1867) a value of 51.70hs, which does not match the value found in 1994. The amplitudes found were 0.3 and 0.4 mag respectively.

Context. The Centaurs are a transitional population of minor bodies of the solar system and the evolutionary link between the trans-Neptunian objects and the short period comets. The surface properties of these objects are very peculiar, because currently available data suggest that their visual surface colors divide the population into two distinc...

Astrometry of Neptune XIII [ESO VLT-Cerro Paranal 309]

Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths and using techniques that are impossible with an in situ flyby. We report here such observations in support of the EPOXI spacecraft flyby of comet 103P/Hartley 2. The nucleus is small an...

In this work we present the progress made in the last year related to the project of automation of the Meade 16" Horacio Ghielmetti Telescope (HGT), located on the Burek Hill of the Complejo Astronómico El Leoncito, San Juan, Argentina. With an experience of more than 6 months of working remotely, we summarize the problems we had and the solutions...

The goal of the paper is to present new results on light echoes from young stellar objects. Broad band CCD images were obtained over three months at one-to-two week intervals for the field of NGC 6726, using the large field-of-view remotely-operated telescope on top of Cerro Burek. We detected scattered light echoes around two young, low-amplitude,...

From the point of view of the intrinsic rotation, the Jupiter Trojans are not as well characterized as the main belt asteroids, primarily because the available sample of lightcurves is small and mainly restricted to the largest objects. We have obtained rotational periods and lightcurve amplitudes for 6 Trojan asteroids, which range between values...

The Trojan asteroids orbit about the Lagrangian points of Jupiter and the residence times about their present location are very long for most of them. If these bodies originated in the outer Solar System, they should be mainly composed of water ice, but, in contrast with comets, all the volatiles close to the surface would have been lost long ago....

Two consecutive transits of planetary companion OGLE-TR-111b were observed in the I band. Combining these observations with data from the literature, we find that the timing of the transits cannot be explained by a constant period, and that the observed variations cannot be originated by the presence of a satellite. However, a perturbing planet; wi...

Two consecutive transits of planetary companion OGLE-TR-111b were observed in the I band. Combining these observations with data from the literature, we find that the timing of the transits cannot be explained by a constant period and that the observed variations cannot be originated by the presence of a satellite. However, a perturbing planet with...

All the Trojan asteroids orbit about the Sun at roughly the same heliocentric distance as Jupiter. Differences in the observed visible reflection spectra range from neutral to red, with no ultra-red objects found so far. Given that the Trojan asteroids are collisionally evolved, a certain degree of variability is expected. Additionally, cosmic radi...

All the Trojan asteroids orbit about the Sun at roughly the same heliocentric distance as Jupiter. Differences in the observed visible reflection spectra range from neutral to red, with no ultra-red objects found so far. Given that the Trojan asteroids are collisionally evolved, a certain degree of variability is expected. Additionally, cosmic radi...

Context. The physical surface properties of a trans-Neptunian Object is believed to be mainly produced as a result of interplay between irradiation from different kinds of cosmic rays and collisions. Objects recently resurfaced by collisions are likely to have very different physical properties from those of the bulk population. In particular, pris...

This review summarizes the main dynamical properties of the planetary rings, mainly concerning their origin and evolution. Particularly, we discuss the different sources of dissipation of orbital energy, which, for the known systems, render orbital decay timescales much shorter than the age of the Solar system. We describe briefly the dynamical the...

A simple and general description of the dynamics of a narrow-eccentric ring is presented. We view an eccentric ring which precesses uniformly at a slow rate as exhibiting a global m=1 mode, which can be seen as originating from a standing wave superposed on an axisymmetric background. We adopt a continuum description using the language of fluid dyn...

We consider a close stellar fly-by as an explanation for the abrupt termination of the classical Edgeworth–Kuiper belt at around 50 AU from the Sun, and also for the high values of orbital excitation observed. By the use of numerical simulations we study a scenario in which a close stellar fly-by truncates the trans-neptunian cometary population as...

Objects in 3:2 mean motion resonance with Neptune are protected from close encounters with Neptune by the resonance. Bodies in orbits with semi-major axis between 39.5 and about 42AU are not protected by the resonance; indeed due to overlapping secular resonances, the eccentricities of orbits in this region are driven up so that a close encounter w...

We use a simple model of the dynamics of a narrow-eccentric ring, to put some constraints on some of the observable properties of the real systems. In this work we concentrate on the case of the ‘Titan ringlet of Saturn’. Our approach is fluid-like, since our description is based on normal modes of oscillation rather than in individual particle or...

Our goal is to determine whether or not the observed sudden termination of the Edgeworth–Kuiper belt can be the result of perturbations from a hypothetical planet. We investigate the effects that such an object would produce on the primordial orbital distribution if the trans-neptunian objects, for a range of masses and orbital parameters of the hy...

The effects that a hypothetical trans-Plutonian planet would produce on theorbital distribution of the Classical Edgeworth-Kuiper-Belt, has beensurveyed for different physical and orbital parameters of the hypotheticalbody in Melita et al. (2003a). The best fits were obtained by a moderatelyeccentric and inclined Earth-sized object with a semimajor...

We examine possible locations for the primordial disk of the Edgeworth–Kuiper Belt (EKB), using several subsets of the known objects as markers of the total mass distribution. Using a secular perturbation theory, we find that the primordial plane of the EKB could have remained thin enough to escape detection only if it is clustered very closely abo...

We study the effects of a Mars-like planetoid with a semimajor axis at about ∼60 AU orbiting embedded in the primordial Edgeworth–Kuiper belt (EKB). The origin of such an object can be explained in the framework of our current understanding of the origin of the outer Solar System, and a scenario for the orbital transport mechanism to its present lo...

We studey two different scenarios in which an external perturber can truncate the trans-Neptunian cometary population and we give plausibility arguments regarding both of them. First we study the perturbations induced in the Edgeworth-Kuiper Belt (EKB) by a stellar encounter. We also investigate the effects of a planetoid with semimajor axis at abo...

In this paper, we discuss some problems concerning the formation of Uranus and Neptune. We find that the adoption of reduced Hill spheres as the region of close interaction between planetesimals introduces an enhancement of the gravitational cross-sections in previous numerical simulations. We also discuss a way to make possible the formation of Ur...

The Lagrangian equilateral points of a planetary orbit are points of equilibrium that trail at 60°, ahead (L4) or behind (L5), the trajectory of a planet. Jupiter is the only major planet in our Solar system harbouring a known population of asteroids at those locations. Here we report the existence of orbits close to the Lagrangian points of Saturn...

We present a numerical algorithm designed to study the evolution of a distribution of solid particles orbiting around the Sun that could be applied to similar systems in which fc ≤ Ω/2π, where fc is the frequency of collisions, and Ω is the orbital angular speed. A number of sample particles are used to represent the whole system. Binary collisions...

A set of self-consistent simulations of the formation of Uranus and Neptune are performed to study the evolution of the native KBOs in the process. Our main goal is to have a deeper understanding of the impact of the formation of the outer planets on the present orbital structure of the trans-neptunian region. We aim to understand if resonance capt...

In this work we are interested in the present dynamical structure of the trans-neptunian region. It is known that at moderate to high eccentricities, stable orbits lie close to an exterior-mean-motion resonance with Neptune (NMMR). We study some NMMRs under different points of view. Intrinsic probabilities of collision and dynamical diffusion time-...

The Lagrangian equilateral points of a planetary orbit are points of equilibrium that trail at 60 deg, ahead (L4) or behind (L5), the trajectory of the planet. Jupiter is the only major planet in our Solar System harbouring a known population of asteroids at those locations. Here we report the existence of orbits close to the Lagrangian points of S...

A set of self-consistent simulations of the formation of Uranus and Neptune are performed to study the evolution of the native KBO's in the process. Our main goal is to have a deeper understanding of the impact of the formation of the outer planets on the present orbital structure of the trans-Neptunian region. We aim to understand if resonance cap...

A self-consistent study of the formation of planetary bodies beyond the orbit of Saturn and the evolution of Kuiper disks is carried out by means of an N-body code where accretion and gravitational encounters are considered. This investigation is focused on the aggregation of massive bodies in the outer planetary region and on the consequences of s...

Albert is the only numbered asteroid that remains lost at present. This object has been discovered while it was making a close apporach to the Earth by Johann Palisa in the Imperial Observatory of Vienna. According to the standard procedure of the time, a number was assigned to it shortly after a preliminar orbit has been obtained and it was named...

The existence of stable orbits in the interplanetary region between Uranus and Neptune over the lifetime of the Solar System has been reported by Holman (1997,Nature387, 785–788). A long-term integration of test particles in that zone resulted in a number of surviving bodies with semimajor axis roughly between 24 and 27 AU, and eccentricities and i...

De acuerdo a los más recientes estudios sobre la formación de Urano y Neptuno, éstos podrían haber sufrido una importante migración radial hacia el exterior, debido al intercambio de momento angular con los planetesimales presentes en esa región durante las últimas etapas de la formación del Sistema Solar. Esta migración radial habría tenido import...

A self-consistent study of the formation of planetary bodies beyond the orbit of Saturn and the evolution of Kuiper disks is carried out by means of a N-body code where accretion and gravitational encounters are considered. This investigation is focused on the aggregation of massive bodies in the outer planetary region and on accretion events in th...

Numerical integrations of a three-body problem, consisting of the Sun and two planets under the influence of both accretion and dynamical friction forces, evolve into planetary resonance when the inner body is more massive. After a transient, the ratio of the periods oscillates closely about a commensurable value; the semimajor axes of both bodies...

Thesis (Ph. D.)--University of York, 1996.