De Troianis: The Trojans in the Planetary System

Trojan objects are minor bodies having stable orbits in the L4 and L5 Lagrangian points of a planet. Mars, Jupiter, and Neptune are known to support Trojans, but Saturn and Uranus are also believed to share their orbits with similar populations of small bodies. Recent dynamical modeling suggests a genetic relationship among transneptunian objects (TNOs) and Jupiter and Neptune Trojans: All these bodies are believed to have formed at large heliocentric distances in a region rich in frozen volatiles. In this context, the analysis and the comparison of the physical properties of Trojans, Centaurs, and TNOs can help us to constrain the link among them and the scenario of the planetary formation in the outer solar system. This chapter presents an overview of current knowledge of the physical properties of Trojans. Since the Jupiter Trojans are the most well studied of the Trojan populations, discussion is centered on the analysis of the properties of this group and comparison with asteroids, comets, Centaurs, and TNOs. The physical characteristics of Jupiter Trojans share some similarities with those of the other populations of small bodies of the outer solar system, but also some notable differences. Some analogies with neutral/less-red Centaurs suggest that Jupiter Trojans are more similar to the active and post-active comets than to the non-active icy bodies. This may support a genetical link among these objects, but the complete puzzle is still far from being understood.

[1]  David Jewitt,et al.  CCD spectra of asteroids. II - The Trojans as spectral analogs of cometary nuclei , 1990 .

[2]  Joseph Veverka,et al.  The composition of the Trojan asteroids , 1980, Nature.

[3]  Barucci,et al.  Physical Properties of Trojan and Centaur Asteroids , 2002 .

[4]  L. McFadden,et al.  CCD reflectance spectra of selected asteroids. I - Presentation and data analysis considerations , 1992 .

[5]  F. Vilas,et al.  CCD Reflectance Spectra of Selected Asteroids. II. Low-Albedo Asteroid Spectra and Data Extraction Techniques , 1993 .

[6]  Emmanuel Lellouch,et al.  The Spectrum of Comet Hale-Bopp (C/1995 O1) Observed with the Infrared Space Observatory at 2.9 Astronomical Units from the Sun , 1997, Science.

[7]  R. Gomes.  Dynamical Effects of Planetary Migration on the Primordial Asteroid Belt , 1997 .

[8]  C. Barbieri,et al.  Visible Spectroscopy of Dark, Primitive Asteroids , 1994 .

[9]  Fernando Roig,et al.  A Semianalytical Model for the Motion of the Trojan Asteroids: Proper Elements and Families , 2001 .

[10]  K. Tsiganis,et al.  Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets , 2005, Nature.

[11]  D. Britt,et al.  Asteroid Density, Porosity, and Structure , 2002 .

[12]  D. Hamilton,et al.  On the Origin of the Trojan Asteroids: Effects of Jupiter's Mass Accretion and Radial Migration , 2000, astro-ph/0007296.

[13]  J. Brucato,et al.  308 Polyxo: ISO-SWS spectrum up to 26 micron , 2004 .

[14]  K. Noll.  Solar System binaries , 2005, Proceedings of the International Astronomical Union.

[15]  Larry A. Lebofsky,et al.  The composition and origin of the C, P, and D asteroids: Water as a tracer of thermal evolution in the outer belt , 1990 .

[16]  Harold F. Levison,et al.  From the Kuiper Belt to Jupiter-Family Comets: The Spatial Distribution of Ecliptic Comets☆ , 1997 .

[17]  F. Roig,et al.  Planetary Migration and the Effects of Mean Motion Resonances on Jupiter’s Trojan Asteroids , 2001 .

[18]  Gabriele Arnold,et al.  A Model of Spectral Albedo of Particulate Surfaces: Implications for Optical Properties of the Moon , 1999 .

[19]  E. Cloutis,et al.  Near-Infrared Spectroscopy of Primitive Solar System Objects , 1994 .

[20]  M. A’Hearn,et al.  Studies of proton-irradiated cometary-type ice mixtures , 1983 .

[21]  C. Trujillo,et al.  A Thick Cloud of Neptune Trojans and Their Colors , 2006, Science.

[22]  Hans Rickman,et al.  Nuclear magnitudes and the size distribution of Jupiter family comets , 2006 .

[23]  B. Hapke,et al.  Bidirectional reflectance spectroscopy. I - Theory. [of planetary surfaces , 1981 .

[24]  T. Owen,et al.  10 Hygiea: ISO Infrared Observations , 2002 .

[25]  Joshua Patrick Emery,et al.  The surface composition of Trojan asteroids: constraints set by scattering theory , 2004 .

[26]  T. Owen,et al.  Near-Infrared Spectroscopy of Low-Albedo Surfaces of the Solar System: Search for the Spectral Signature of Dark Material , 1998 .

[27]  B. Hapke.  Theory of reflectance and emittance spectroscopy , 1993 .

[28]  Hans Scholl,et al.  Capture of Trojans by a Growing Proto-Jupiter , 1998 .

[29]  Physical Properties of Trans-Neptunian Object (20000) Varuna , 2002, astro-ph/0201082.

[30]  G. Strazzulla.  Chemistry of Ice Induced by Bombardment with Energetic Charged Particles , 1998 .

[31]  R. Duffard,et al.  S3OS2: the visible spectroscopic survey of 820 asteroids , 2004 .

[32]  Elisabetta Dotto,et al.  Optical alteration of complex organics induced by ion-irradiation: 1. Laboratory experiments suggest unusual space weathering trend. , 2004 .

[33]  F. Marzari,et al.  The Role of Secular Resonances in the History of Trojans , 2000 .

[34]  Dean C. Hines,et al.  Spitzer Observations of the Dust Coma and Nucleus of 29P/Schwassmann-Wachmann 1 , 2004 .

[35]  Paul J. Stomski,et al.  A low density of 0.8 g cm-3 for the Trojan binary asteroid 617 Patroclus , 2006, Nature.

[36]  F. Marzari,et al.  The surface composition of Jupiter Trojans: Visible and near-infrared survey of dynamical families ☆ , 2006 .

[37]  David Jewitt,et al.  Spectroscopic Search for Water Ice on Jovian Trojan Asteroids , 2006 .

[38]  Daniel D. Durda,et al.  Asteroids Do Have Satellites , 2002 .

[39]  M. Martino,et al.  Spectroscopic observations of Jupiter Trojans , 2004 .

[40]  K. Tsiganis,et al.  Origin of the orbital architecture of the giant planets of the Solar System , 2005, Nature.

[41]  Z. Ivezic,et al.  Solar system objects observed in the Sloan Digital Sky Survey commissioning data , 2001 .

[42]  Z. Ivezic,et al.  The properties of Jovian Trojan asteroids listed in SDSS Moving Object Catalogue 3 , 2007, astro-ph/0703026.

[43]  D. C. Jewitt,et al.  Population and Size Distribution of Small Jovian Trojan Asteroids , 2000, astro-ph/0004117.

[44]  Harold F. Levison,et al.  Planetary migration in a planetesimal disk: why did Neptune stop at 30 AU? , 2004 .

[45]  Julio A. Fernández,et al.  Some dynamical aspects of the accretion of Uranus and Neptune: The exchange of orbital angular momentum with planetesimals , 1984 .

[46]  Tjie SIIORT-PERJOD.  The Kuiper Belt , 1997 .

[47]  Jack J. Lissauer,et al.  Formation of the Giant Planets by Concurrent Accretion of Solids and Gas , 1995 .

[48]  L. Tannenbaum.  Laboratory Studies , 2010, Pediatric Orthopaedics and Sports Injuries.

[49]  吉田 二美.  Size and spatial distributions of sub-km main-belt asteroids , 2002 .

[50]  Renu Malhotra,et al.  The origin of Pluto's orbit: implications for the , 1994, astro-ph/9504036.

[51]  David Jewitt,et al.  The Albedo Distribution of Jovian Trojan Asteroids , 2003 .

[52]  Neptune’s Migration into a Stirred-Up Kuiper Belt: A Detailed Comparison of Simulations to Observations , 2005, astro-ph/0507319.

[53]  M. Moore,et al.  Laboratory Studies of the Formation of Methanol and Other Organic Molecules by Water+Carbon Monoxide Radiolysis: Relevance to Comets, Icy Satellites, and Interstellar Ices , 1999 .

[54]  W. R. Thompson,et al.  Coloration and darkening of methane clathrate and other ices by charged particle irradiation: applications to the outer solar system. , 1987, Journal of geophysical research.

[55]  K. Tsiganis,et al.  Chaotic capture of Jupiter's Trojan asteroids in the early Solar System , 2005, Nature.

[56]  Andrea Milani,et al.  The Trojan asteroid belt: Proper elements, stability, chaos and families , 1993 .

[57]  Faith Vilas,et al.  Iron Alteration Minerals in the Visible and Near-Infrared Spectra of Low-Albedo Asteroids , 1994 .

[58]  F. Marzari,et al.  Visible spectroscopic and photometric survey of L5 Trojans: investigation of dynamical families , 2004 .

[59]  W. Hartmann,et al.  Trojan and Hilda asteroid lightcurves. I - Anomalously elongated shapes among Trojans (and Hildas?) , 1988 .

[60]  Dale P. Cruikshank,et al.  Thermal emission spectroscopy (5.2–38 μm) of three Trojan asteroids with the Spitzer Space Telescope: Detection of fine-grained silicates , 2006 .

[61]  Robert H. Brown,et al.  Constraints on the surface composition of Trojan asteroids from near-infrared (0.8–4.0 μm) spectroscopy , 2003 .

[62]  Orbital Evolution of Planets Embedded in a Planetesimal Disk , 1999, astro-ph/9902370.

[63]  J. Chambers,et al.  The Primordial Excitation and Clearing of the Asteroid Belt , 2001 .

[64]  E. M. Shoemaker,et al.  Trojan asteroids - Populations, dynamical structure and origin of the L4 and L5 swarms , 1989 .

[65]  P. Robutel,et al.  The resonant structure of Jupiter's Trojan asteroids – I. Long‐term stability and diffusion , 2006 .

[66]  A. Rivkin,et al.  Spectroscopy and photometry of Mars Trojans , 2003 .

[67]  S. Peale.  The Effect of the Nebula on the Trojan Precursors , 1993 .

[68]  Fumi Yoshida,et al.  Size Distribution of Faint Jovian L4 Trojan Asteroids , 2005 .

[69]  Charalampos Skokos,et al.  Stability of the Trojan asteroids , 1997 .

[70]  J. Dunlap,et al.  Minor planets. III - Lightcurves of a Trojan asteroid. , 1969 .

[71]  Alfred Edward Ringwood,et al.  Origin of the Earth and Moon , 1979 .

[72]  B. Hapke.  Bidirectional reflectance spectroscopy: 1. Theory , 1981 .

[73]  William K. Hartmann,et al.  The Time-Dependent Intense Bombardment of the Primordial Earth/Moon System , 2000 .

[74]  M J Gaffey,et al.  Phyllosilicate Absorption Features in Main-Belt and Outer-Belt Asteroid Reflectance Spectra , 1989, Science.

[75]  G. Wetherill.  An alternative model for the formation of the asteroids , 1992 .

[76]  Andrea Milani,et al.  Asteroid Proper Elements and the Dynamical Structure of the Asteroid Main Belt , 1994 .

[77]  Richard P. Binzel,et al.  Trojan, Hilda, and Cybele asteroids: New lightcurve observations and analysis , 1992 .

[78]  H. Scholla,et al.  Dynamics of Mars Trojans , 2005 .

[79]  K. J. Meech,et al.  Spitzer Spectral Observations of the Deep Impact Ejecta , 2006, Science.

[80]  H. Boehnhardt,et al.  Aqueous altered silicates at the surface of two Plutinos , 2004 .

[81]  E. Tedesco,et al.  Compositional Structure of the Asteroid Belt , 1982, Science.

[82]  F. De Luise,et al.  Visible spectroscopic and photometric survey of Jupiter Trojans: Final results on dynamical families , 2007, 0704.0350.

[83]  Analysis of the Rotational Properties of Kuiper Belt Objects , 2006, astro-ph/0601257.

[84]  Renu Malhotra,et al.  The origin of Pluto's peculiar orbit , 1995, Nature.

[85]  A. Fitzsimmons,et al.  A spectroscopic survey of D-type asteroids , 1994 .