In this paper we present the observational campaign carried out at ESO NTT and VLT in April and M... more In this paper we present the observational campaign carried out at ESO NTT and VLT in April and May 2006 to investigate the nature and the structure of the Near Earth Object (144898) 2004 VD17. In spite of a great quantity of dynamical information, according to which it will have a close approach with the Earth in the next century, the physical properties of this asteroid are largely unknown. We performed visible and near-infrared photometry and spectroscopy, as well as polarimetric observations. Polarimetric and spectroscopic data allowed us to classify 2004 VD17 as an E-type asteroid. A good agreement was also found with the spectrum of the aubrite meteorite Mayo Belwa. On the basis of the polarimetric albedo (p v = 0.45) and of photometric data, we estimated a diameter of about 320 m and a rotational period of about 2 hours. The analysis of the results obtained by our complete survey have shown that (144898) 2004 VD17 is a peculiar NEO, since it is close to the breakup limits for fast rotator asteroids, as defined by Pravec and Harris (2000). These results suggest that a more robust structure must be expected, as a fractured monolith or a rubble pile in a "strength regime" (Holsapple 2002).
In this paper the authors present an analysis of the main biases which affect the present availab... more In this paper the authors present an analysis of the main biases which affect the present available data on rotational properties of asteroids. Suggestions about observational plans are given. The authors try to outline a tentative general scenario of the asteroid evolution, pointing out the large importance of the self-gravitation of the body on the rotational properties of the collision's outcomes.
ABSTRACT In this paper the authors present an analysis of the main biases which affect the presen... more ABSTRACT In this paper the authors present an analysis of the main biases which affect the present available data on rotational properties of asteroids. Suggestions about observational plans are given. The authors try to outline a tentative general scenario of the asteroid evolution, pointing out the large importance of the self-gravitation of the body on the rotational properties of the collision's outcomes.
In this introductory paper, we review the subjects addressed during the meeting ''Solar System Sc... more In this introductory paper, we review the subjects addressed during the meeting ''Solar System Science before and after Gaia'', which is at the origin of the content of this special issue. The several unknowns affecting our knowledge of the dynamical and physical properties of asteroids are briefly discussed, along with the perspectives opened by the availability of Gaia data and other surveys. The role of complementary observations is also stressed.
The importance of catastrophic collisions as an evolutionary process determining the main physica... more The importance of catastrophic collisions as an evolutionary process determining the main physical properties of asteroids has been recognized since a long time, but only recently its central role against other evolutionary mechanisms, such as accretion or small-scale cratering phenomena, has become apparent. For catastrophic collision we mean a major impact event, causing extensive rupture of the target's solid-state cohesion and ejection of large broken fragments. According to the laboratory impact experiments performed by Fujiwara et al. (1977), a high-velocity collision can result into a variety of different outcomes, depending mainly on the specific energy delivered to the target by the projectile body. These outcomes can range from cratering to spallation to complete disruption, with different velocities of the ejected material in the various cases. When we try to extrapolate these results to real asteroids, we must take into account the fact that, in order to cause the co...
The role of angular momentum transfer to determine the mass ratio of binaries
A thermodynamical approach to the problem of star formation shows how the characteristics of the ... more A thermodynamical approach to the problem of star formation shows how the characteristics of the outcomes depend on the initial conditions (thermal and rotational energies) and on the distribution of the angular momentum among the various parts of the system when the last stages of collapse are assumed to be adiabatic. In the case of a binary outcome, the distribution
A Unique Spectral Slope-Exposure Relation for Silicate-Rich Main Belt and Near-Earth Asteroids
Space environment acts on optical properties of silicate-rich asteroid surfaces: older asteroids ... more Space environment acts on optical properties of silicate-rich asteroid surfaces: older asteroids are expected to be generally redder and darker than the younger ones. The space weathering depends mainly on the age, but it may depend also on the distance from the Sun, especially if the Sun-dependent effects (for example, ion bombardment) are assumed as dominant. With the aid of
An extensive analysis of the Maria family is presented. A reconstruction of the original ejection... more An extensive analysis of the Maria family is presented. A reconstruction of the original ejection velocity field of the fragments suggests that a substantial amount of relatively large fragments has been probably injected into the neighbouring 3/1 mean motion resonance with Jupiter. This is also confirmed by an analysis of the size distribution of the family, suggesting that about 10 objects in the 15--30 km size range have been probably lost. As a consequence, Maria's family can be seen as one of the most promising candidates as the source of the "giant" near--Earth asteroids 433 Eros and 1036 Ganymed. This is also confirmed by an extensive spectroscopic survey of the family members in the 5000--10000 Aspectral range. The obtained spectra are very similar and very much resemble the known spectra of Eros and Ganymed. 3 1 Introduction Asteroid families are the outcomes of energetic impact events occurred in the asteroid main belt during the history of the Solar System. ...
Statistical properties of visual and eclipsing binaries
The catalogues of visual and eclipsing binaries have been analyzed by means of a multivariate sta... more The catalogues of visual and eclipsing binaries have been analyzed by means of a multivariate statistical method, with the purpose of putting into evidence mutual relations among the observed quantities as well as clustering properties in the multi-dimensional space.
By multivariate statistical analysis the authors point out correlations among physical parameters... more By multivariate statistical analysis the authors point out correlations among physical parameters of spectroscopic binary systems. The best clustering has been outlined allowing a direct interpretation in terms of H.R. diagram in the maximum variance plane. Cluster analysis confirms the probable period-eccentricity relation. The existence of a well defined cluster with strongly unbalanced masses supports the hypothesis of an original bimodality in the mass ratio distribution.
In this paper we present the observational campaign carried out at ESO NTT and VLT in April and M... more In this paper we present the observational campaign carried out at ESO NTT and VLT in April and May 2006 to investigate the nature and the structure of the Near Earth Object (144898) 2004 VD17. In spite of a great quantity of dynamical information, according to which it will have a close approach with the Earth in the next century, the physical properties of this asteroid are largely unknown. We performed visible and near-infrared photometry and spectroscopy, as well as polarimetric observations. Polarimetric and spectroscopic data allowed us to classify 2004 VD17 as an E-type asteroid. A good agreement was also found with the spectrum of the aubrite meteorite Mayo Belwa. On the basis of the polarimetric albedo (p v = 0.45) and of photometric data, we estimated a diameter of about 320 m and a rotational period of about 2 hours. The analysis of the results obtained by our complete survey have shown that (144898) 2004 VD17 is a peculiar NEO, since it is close to the breakup limits for fast rotator asteroids, as defined by Pravec and Harris (2000). These results suggest that a more robust structure must be expected, as a fractured monolith or a rubble pile in a "strength regime" (Holsapple 2002).
In this paper the authors present an analysis of the main biases which affect the present availab... more In this paper the authors present an analysis of the main biases which affect the present available data on rotational properties of asteroids. Suggestions about observational plans are given. The authors try to outline a tentative general scenario of the asteroid evolution, pointing out the large importance of the self-gravitation of the body on the rotational properties of the collision's outcomes.
ABSTRACT In this paper the authors present an analysis of the main biases which affect the presen... more ABSTRACT In this paper the authors present an analysis of the main biases which affect the present available data on rotational properties of asteroids. Suggestions about observational plans are given. The authors try to outline a tentative general scenario of the asteroid evolution, pointing out the large importance of the self-gravitation of the body on the rotational properties of the collision's outcomes.
In this introductory paper, we review the subjects addressed during the meeting ''Solar System Sc... more In this introductory paper, we review the subjects addressed during the meeting ''Solar System Science before and after Gaia'', which is at the origin of the content of this special issue. The several unknowns affecting our knowledge of the dynamical and physical properties of asteroids are briefly discussed, along with the perspectives opened by the availability of Gaia data and other surveys. The role of complementary observations is also stressed.
The importance of catastrophic collisions as an evolutionary process determining the main physica... more The importance of catastrophic collisions as an evolutionary process determining the main physical properties of asteroids has been recognized since a long time, but only recently its central role against other evolutionary mechanisms, such as accretion or small-scale cratering phenomena, has become apparent. For catastrophic collision we mean a major impact event, causing extensive rupture of the target's solid-state cohesion and ejection of large broken fragments. According to the laboratory impact experiments performed by Fujiwara et al. (1977), a high-velocity collision can result into a variety of different outcomes, depending mainly on the specific energy delivered to the target by the projectile body. These outcomes can range from cratering to spallation to complete disruption, with different velocities of the ejected material in the various cases. When we try to extrapolate these results to real asteroids, we must take into account the fact that, in order to cause the co...
The role of angular momentum transfer to determine the mass ratio of binaries
A thermodynamical approach to the problem of star formation shows how the characteristics of the ... more A thermodynamical approach to the problem of star formation shows how the characteristics of the outcomes depend on the initial conditions (thermal and rotational energies) and on the distribution of the angular momentum among the various parts of the system when the last stages of collapse are assumed to be adiabatic. In the case of a binary outcome, the distribution
A Unique Spectral Slope-Exposure Relation for Silicate-Rich Main Belt and Near-Earth Asteroids
Space environment acts on optical properties of silicate-rich asteroid surfaces: older asteroids ... more Space environment acts on optical properties of silicate-rich asteroid surfaces: older asteroids are expected to be generally redder and darker than the younger ones. The space weathering depends mainly on the age, but it may depend also on the distance from the Sun, especially if the Sun-dependent effects (for example, ion bombardment) are assumed as dominant. With the aid of
An extensive analysis of the Maria family is presented. A reconstruction of the original ejection... more An extensive analysis of the Maria family is presented. A reconstruction of the original ejection velocity field of the fragments suggests that a substantial amount of relatively large fragments has been probably injected into the neighbouring 3/1 mean motion resonance with Jupiter. This is also confirmed by an analysis of the size distribution of the family, suggesting that about 10 objects in the 15--30 km size range have been probably lost. As a consequence, Maria's family can be seen as one of the most promising candidates as the source of the "giant" near--Earth asteroids 433 Eros and 1036 Ganymed. This is also confirmed by an extensive spectroscopic survey of the family members in the 5000--10000 Aspectral range. The obtained spectra are very similar and very much resemble the known spectra of Eros and Ganymed. 3 1 Introduction Asteroid families are the outcomes of energetic impact events occurred in the asteroid main belt during the history of the Solar System. ...
Statistical properties of visual and eclipsing binaries
The catalogues of visual and eclipsing binaries have been analyzed by means of a multivariate sta... more The catalogues of visual and eclipsing binaries have been analyzed by means of a multivariate statistical method, with the purpose of putting into evidence mutual relations among the observed quantities as well as clustering properties in the multi-dimensional space.
By multivariate statistical analysis the authors point out correlations among physical parameters... more By multivariate statistical analysis the authors point out correlations among physical parameters of spectroscopic binary systems. The best clustering has been outlined allowing a direct interpretation in terms of H.R. diagram in the maximum variance plane. Cluster analysis confirms the probable period-eccentricity relation. The existence of a well defined cluster with strongly unbalanced masses supports the hypothesis of an original bimodality in the mass ratio distribution.
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Papers by P. Paolicchi