Surface composition and dynamical evolution of two retrograde objects in the outer solar system: 2008 YB 3 and 2005 VD (original) (raw)

Dynamical and physical properties of comet--asteroid transition objects

Astronomy and Astrophysics

In the last few years it has been pointed out that, from both physical and dynamical point of view, it is becoming more and more difficult to distinguish comets from asteroids and indeed there are some examples of small bodies first designated as comets which had, later, to be reclassified as asteroids and vice versa . In order to investigate the evolutionary path of comets and asteroids in terms of both dynamical and physical properties, we performed spectroscopic observations of three objects discovered between 1990 and 1995 -(6042) 1990 WW 2 , (6144) 1994 EQ 3 , and 1995 QY 2 -and analyzed their orbital evolution. Obtained spectra show the typical trend of low-albedo, "primitive" objects, similar to those of outer-belt asteroids and comet nuclei. The dynamical analysis shows that (6042) 1990 WW 2 is on a stable orbit with a typical asteroidal behavior; (6144) 1994 EQ 3 is on a Jupitercrossing chaotic orbit and in the past could have spent some time in a Jupiter's horsehoe orbit; 1995 QY 2 is a Mars crosser and librates about the 15/7 resonance with Jupiter and has a 40% chance to make a transition from asteroid to comet orbit over a timescale of about 3-5×10 5 yr.

A portrait of the extreme solar system object 2012 DR 30

Astronomy & Astrophysics, 2013

2012 DR 30 is a recently discovered solar system object on a unique orbit, with a high eccentricity of 0.9867, a perihelion distance of 14.54 AU, and a semi-major axis of 1109 AU, in this respect outscoring the vast majority of trans-Neptunian objects (TNOs). We performed Herschel/PACS and optical photometry to uncover the size and albedo of 2012 DR 30 , together with its thermal and surface properties. The body is 185 km in diameter and has a relatively low V-band geometric albedo of ∼8%. Although the colours of the object indicate that 2012 DR 30 is an RI taxonomy class TNO or Centaur, we detected an absorption feature in the Z-band that is uncommon among these bodies. A dynamical analysis of the target's orbit shows that 2012 DR 30 moves on a relatively unstable orbit and was most likely only recently placed on its current orbit from the most distant and still highly unexplored regions of the solar system. If categorised on dynamical grounds 2012 DR 30 is the largest Damocloid and/or high inclination Centaur observed so far.

The Evolution of Jupiter Family Comets over 2000 Years

Symposium - International Astronomical Union, 1992

The orbital evolution of the whole sample sample of short-period comets was computed by numerical integrations for a time interval of 2000 yr centered on the present epoch. This data base is intended to serve in various studies involving the statistics of orbital evolution and correlation with physical parameters or discovery circumstances. We present some results concerning the following aspects: the evolution of the orbital elements and their past-future asymmetry, statistics on the discovery of comets and on the encounters of comets with Jupiter.

Dynamical Evolution of Ecliptic Comets

Comets II, 2004

In this chapter, we review the enormous progress that has been made in our understanding of the dynamical evolution of these bodies. We begin by reviewing the evidence that Jupiter-family comets (JFCs; those with 2 < T < 3) form a dynamically distinct class of comets that originate in a flattened disk beyond Neptune. We present a model for the distribution of comets throughout the JFC and Centaur regions that is consistent with current observations, although further observations and numerical simulations in the Centaur region are called for. We then discuss dynamical results (since confirmed by observations) that a significant amount of material that was scattered by Neptune during the early stages of planet formation could persist today in the form of a "scattered disk" of bodies with highly eccentric orbits beyond Neptune. We describe the dynamical mechanisms believed responsible for the longevity of the surviving bodies and argue that if objects in the Kuiper belt and scattered disk have similar size distributions, then the scattered disk is likely to be the primary source of JFCs and Centaurs. Finally, we describe the importance of understanding the ecliptic comet population for the purposes of determining impact rates on the satellites of the giant planets and of age determinations of the satellite surfaces. We present tables of impact rates based on the best currently available analyses. Further refinements of these rates and age determinations await better observations of the Centaur population (including its size distribution), as well as a better understanding of the formation and early dynamical evolution of the outer solar system.

Assessing the physical nature of near-Earth asteroids through their dynamical histories

Icarus, 2014

We analyze a sample of 139 near-Earth asteroids (NEAs), defined as those that reach perihelion distances q < 1.3 au, and that also fulfill the conditions of approaching or crossing Jupiter's orbit (aphelion distances Q > 4.8 au), having Tisserand parameters 2 < T < 3 and orbital periods P < 20 yr. In order to compare the dynamics, we also analyze a sample of 42 Jupiter family comets (JFCs) in near-Earth orbits, i.e. with q < 1.3 au. We integrated the orbits of these two samples for 10 4 yr in the past and in the future. We find that the great majority of the NEAs move on stable orbits during the considered period, and that a large proportion of them are in one of the main mean motion resonances with Jupiter, in particular the 2:1. We find a strong coupling between the perihelion distance and the inclination in the motion of most NEAs, due to Kozai mechanism, that generates many sungrazers. On the other hand, most JFCs are found to move on very unstable orbits, showing large variations in their perihelion distances in the last few 10 2 − 10 3 yr, which suggests a rather recent capture in their current near-Earth orbits. Even though most NEAs of our sample move in typical 'asteroidal' orbits, we detect a small group of NEAs whose orbits are highly unstable, resembling those of the JFCs.

Asteroids in the inner Solar system - II. Observable properties

Monthly Notices of the Royal Astronomical Society, 2002

This paper presents synthetic observations of long-lived, coorbiting asteroids of Mercury, Venus, the Earth and Mars. Our sample is constructed by taking the limiting semimajor axes, differential longitudes and inclinations for long-lived stability provided by simulations. The intervals are randomly populated with values to create initial conditions. These orbits are re-simulated to check that they are stable and then re-sampled every 2.5 years for 1 million years. The Mercurian sample contains only horseshoe orbits, the Martian sample only tadpoles. For both Venus and the Earth, the greatest concentration of objects on the sky occurs close to the classical Lagrange points at heliocentric ecliptic longitudes of 60 • and 300 •. The distributions are broad especially if horseshoes are present in the sample. The full-width half maximum (FWHM) in heliocentric longitude for Venus is 325 • and for the Earth is 328 •. The mean and most common velocity of these coorbiting satellites coincides with the mean motion of the parent planet, but again the spread is wide with a FWHM for Venus of 27.8 ′′ hr −1 and for the Earth of 21.0 ′′ hr −1. For Mars, the greatest concentration on the sky occurs at heliocentric ecliptic latitudes of ±12 •. The peak of the velocity distribution occurs at 65 ′′ hr −1 , significantly less than the Martian mean motion, while its FWHM is 32.3 ′′ hr −1. The case of Mercury is the hardest of all, as the greatest concentrations occur at heliocentric longitudes of 16.0 • and 348.5 • and so are different from the classical values. The fluctuating eccentricity of Mercury means that these objects can have velocities exceeding 1000 ′′ hr −1 , although the most common velocity is 459 ′′ hr −1 , which is much less than the Mercurian mean motion. A variety of search strategies are discussed, including wide-field CCD imaging, space satellites such as The Global Astrometry Interferometer for Astrophysics (GAIA), ground-based surveys like The Sloan Digital Sky Survey (SDSS), as well as infrared cameras and space-borne coronagraphs.

Distant Comets in the Early Solar System

2000

The main goal of this project is to physically characterize the small outer solar system bodies. An understanding of the dynamics and physical properties of the outer solar system small bodies is currently one of planetary science's highest priorities. The measurement of the size distributions of these bodies will help constrain the early mass of the outer solar system as well as lead to an understanding of the collisional and accretional processes. A study of the physical properties of the small outer solar system bodies in comparison with comets in the inner solar system and in the Kuiper Belt will give us information about the nebular volatile distribution and small body surface processing. We will increase the database of comet nucleus sizes making it statistically meaningful (for both Short-Period and Centaur comets) to compare with those of the Trans-Neptunian Objects. In addition, we are proposing to do active ground-based observations in preparation for several upcoming ...

Observations of the Centaur 1999 UG 5 : Evidence of a Unique Outer Solar System Surface

Publications of the Astronomical Society of the Pacific, 2002

The outer solar system body 1999 UG 5 is a Centaur of medium brightness and slightly redder color when compared to other Centaurs. Similar to at least of the known Centaurs, it is a Saturn-crosser with 1 5 a mean orbital distance between Saturn and Uranus. We present optical photometry data and near-IR spectra obtained during 2000 September, November, and December. We find a rotation period of hr with 13.41 ‫ע‬ 0.04 an amplitude of mag and a phase curve with a Lumme-Bowell G value of. BVRI 0.102 ‫ע‬ 0.005 Ϫ0.13 ‫ע‬ 0.02 colors are reported, and they confirm the red spectral gradient observed previously. Our spectra reveal that this redward slope extends into near-IR wavelengths and indicates possible localized differences in the surface composition.

Division F Commission 15: Physical Study of Comets and Minor Planets

Proceedings of the International Astronomical Union, 2015

Commission 15 of the International Astronomical Union (IAU), entitled Physical Study of Comets and Minor Planets, was founded in 1935 and dissolved in 2015, following the reorganization of IAU. In 80 years of Commission 15, tremendous progress has been made on the knowledge of these objets, thanks to the combined efforts of ground- and space-based observations, space mission rendezvous and flybys, laboratory simulation and analyses of returned samples, and theoretical and numerical modeling. Together with dynamical studies of the Solar System, this discipline has provided a much deeper understanding of how the Solar System formed and evolved. We present a legacy report of Commission 15, which highlights key milestones in the exploration and knowledge of the small bodies of the Solar System.