On the origin of the unusual orbit of Comet 2P/Encke

Levison, Harold F.; Terrell, Dirk; Wiegert, Paul; Dones, L.; Duncan, Martin J.

doi:10.1016/j.icarus.2005.12.016

Cited by 91 publications

(111 citation statements)

References 29 publications

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“…Levison 1996). We use T J = 3.05 instead of T J = 3.00 because small drifts in T J beyond 3.0 are possible due to non-gravitational forces or terrestrial planet interactions (e.g., Levison et al 2006;Hsieh and Haghighipour 2016). Other authors (e.g., Jewitt et al 2015c) have used T J = 3.08 as the boundary for similar reasons; the resulting list of MBC candidates is the same.…”

Section: Definitions: Active Asteroids and Main Belt Cometsmentioning

confidence: 99%

The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

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We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies.

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Section: Definitions: Active Asteroids and Main Belt Cometsmentioning

confidence: 99%

The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

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“…Farther than 300 AU, the calculations are performed in the barycentric frame and we increased the time step to 50 yr. Comets were removed once they were farther than 1000 AU from the Sun, or if they collided with the Sun or a planet. The terrestrial planets were not included because they only have a minimal effect on the dynamics of the JFCs (Levison et al 2006a) and they would increase computation time by at least an order of magnitude.…”

Section: Numerical Simulation and Initial Conditionsmentioning

confidence: 99%

An updated estimate of the number of Jupiter-family comets using a simple fading law

Brasser

Wang

2015

A&A

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It has long been hypothesised that the Jupiter-family comets (JFCs) come from the scattered disc, an unstable planetesimal population beyond Neptune. This viewpoint has been widely accepted, but a few issues remain, the most prominent of which are the total number of visible JFCs with a perihelion distance q < 2.5 AU and the corresponding number of objects in the scattered disc. In this work we give a robust estimate of the number of visible JFCs with q < 2.5 AU and diameter D > 2.3 km based on recent observational data. This is combined with numerical simulations that use a simple fading law applied to JFCs that come close to the Sun. For this we numerically evolve thousands of comets from the scattered disc through the realm of the giant planets and keep track of their number of perihelion passages with perihelion distance q < 2.5 AU, below which the activity is supposed to increase considerably. We can simultaneously fit the JFC inclination and semi-major axis distribution accurately with a delayed power law fading function of the form Φ m ∝ (M 2 + m 2 ) −k/2 , where Φ m is the visibility, m is the number of perihelion passages with q < 2.5 AU, M is an integer constant, and k is the fading index. We best match both the inclination and semi-major axis distributions when k ∼ 1.4, M = 40, and the maximum perihelion distance below which the observational data is complete is q m ∼ 2.3 AU. From observational data we calculate that a JFC with diameter D = 2.3 km has a typical total absolute magnitude H T = 10.8, and the steady-state number of active JFCs with diameter D > 2.3 km and q < 2.5 AU is of the order of 300 (but with large uncertainties), approximately a factor two higher than earlier estimates. The increased JFC population results in a scattered disc population of 6 billion objects and decreases the observed Oort cloud to scattered disc population ratio to 13, virtually the same as the value of 12 obtained with numerical simulations.

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“…Levison et al (2006), following orbits from the Kuiper belt, deduced that at any one time there should be one to a dozen objects in Encke-like orbits, neglecting both physical decay and nongravitational effects. They found that the time taken for a JFC to attain an Encke-like orbit, dynamically uncoupled from Jupiter, is 0.1 Myr, two orders of magnitude longer than its physical lifetime, but proposed that 2P/Encke might have survived destruction through a period of dormancy.…”

Section: Encke-like Orbitsmentioning

confidence: 99%

Giant comets and mass extinctions of life

Napier

2015

Monthly Notices of the Royal Astronomical Society

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I find evidence for clustering in age of well-dated impact craters over the last 500 Myr. At least nine impact episodes are identified, with durations whose upper limits are set by the dating accuracy of the craters. Their amplitudes and frequency are inconsistent with an origin in asteroid breakups or Oort cloud disturbances, but are consistent with the arrival and disintegration in near-Earth orbits of rare, giant comets, mainly in transit from the Centaur population into the Jupiter family and Encke regions. About 1 in 10 Centaurs in Chiron-like orbits enter Earth-crossing epochs, usually repeatedly, each such epoch being generally of a few thousand years duration. On time-scales of geological interest, debris from their breakup may increase the mass of the near-Earth interplanetary environment by two or three orders of magnitude, yielding repeated episodes of bombardment and stratospheric dusting. I find a strong correlation between these bombardment episodes and major biostratigraphic and geological boundaries, and propose that episodes of extinction are most effectively driven by prolonged encounters with meteoroid streams during bombardment episodes. Possible mechanisms are discussed.

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On the origin of the unusual orbit of Comet 2P/Encke

Cited by 91 publications

References 29 publications

The Main Belt Comets and ice in the Solar System

The Main Belt Comets and ice in the Solar System

An updated estimate of the number of Jupiter-family comets using a simple fading law

Giant comets and mass extinctions of life

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