scholarly journals Dynamical evolution of Oort cloud comets to near-Earth space

2006 ◽  
Vol 2 (S236) ◽  
pp. 43-54 ◽  
Author(s):  
Olga A. Mazeeva
Keyword(s):  
Dynamical Evolution ◽  
Absolute Magnitude ◽  
Oort Cloud ◽  
Outer Solar System ◽  
Earth Space ◽  
Near Earth Space ◽  
Long Period ◽  
Order Of Magnitude ◽  
Orbital Periods ◽  
Stellar Perturbations

AbstractThe dynamical evolution of 2⋅105 hypothetical Oort cloud comets by the action of planetary, galactic and stellar perturbations during 2⋅109 years is studied numerically. The evolution of comet orbits from the outer (104 AU <a<5⋅104 AU, a is semimajor axes) and the inner Oort cloud (5⋅103 AU <a<104 AU) to near-Earth space is investigated separately. The distribution of the perihelion (q) passage frequency in the planetary region is obtained calculating the numbers of comets in every interval of Δ q per year. The flux of long-period (LP) comets (orbital periods P>200 yr) with perihelion distances q<1.5 AU brighter than visual absolute magnitude H10=7 is ∼ 1.5 comets per year, and ∼18 comets with H10<10.9. The ratio of all LP comets with q<1.5 AU to ‘new’ comets is ∼5. The frequency of passages of LP comets from the inner Oort cloud through region q<1.5 AU is ∼3.5⋅10−13 yr−1, that is roughly one order of magnitude less than frequency of passages of LP comets from the outer cloud (∼5.28⋅10−12 yr−1). We show that the flux of ‘new’ comets with 15<q<31 AU is higher than with q<15 AU, by a factor ∼1.7 for comets from the outer Oort cloud and, by a factor ∼7 for comets from the inner cloud. The perihelia of comets from the outer cloud previously passed through the planetary region are predominated in the Saturn-Uranus region. The majority of inner cloud comets come in the outer solar system (q>15 AU), and a small fraction (∼0.01) of them can reach orbits with q<1.5 AU. The frequency of transfer of comets from the inner cloud (a<104 AU) to the outer Oort cloud (a>104 AU), from where they are injected to the region q<1.5 AU, is ∼6⋅10−14 yr−1.

From the Solar system comet cloud to near-Earth space

1999 ◽  
Vol 173 ◽  
pp. 339-344 ◽  
Author(s):  
V.V. Emel'yanenko
Keyword(s):  
Steady State ◽  
Solar System ◽  
Dynamical Evolution ◽  
Oort Cloud ◽  
High Eccentricity ◽  
Earth Space ◽  
Near Earth Space ◽  
Short Period ◽  
Absolute Magnitudes ◽  
Continuous Source

AbstractThe dynamical evolution of objects from different zones of the solar system comet cloud to near-Earth space has been investigated. The steady-state number of objects with perihelion distancesq&lt; 1.5 AU and periodsP &lt;20 yr, arising from the near-parabolic flux of comets with absolute magnitudes brighter thanH10= 7 is ∼ 200 − 1000. The corresponding number for Halley-type comets is hundreds of times larger than the number of known Halley-type comets. The flux of objects in the Centaurs zone, captured from the near-parabolic flux is 300 times as large as the flux of new comets. The total number of cometary objects with semi-major axesain the range 50 &lt;a&lt; 500 AU andq∼ 1 AU is ∼ 10 times as large as the number of active comets. The probability of the transfer of objects from the trans-Neptunian orbits with 35 &lt;q&lt; 50 AU anda∼ 600 AU into the Jupiter family is ∼ 0.0001. The calculations show that trans-Neptunian objects on high-eccentricity orbits can be a significant continuous source for both the replenishment of the Oort cloud and the capture to short-period orbits.

From the Oort cloud to Halley-type comets

1999 ◽  
Vol 173 ◽  
pp. 327-338 ◽  
Author(s):  
J.A. Fernández ◽  
T. Gallardo
Keyword(s):  
Total Population ◽  
Complex Function ◽  
Dynamical Evolution ◽  
Oort Cloud ◽  
Capture Process ◽  
Influx Rate ◽  
Short Period ◽  
Dynamical Properties ◽  
Orbital Periods ◽  
Probability Of Capture

AbstractThe Oort cloud probably is the source of Halley-type (HT) comets and perhaps of some Jupiter-family (JF) comets. The process of capture of Oort cloud comets into HT comets by planetary perturbations and its efficiency are very important problems in comet ary dynamics. A small fraction of comets coming from the Oort cloud − of about 10−2− are found to become HT comets (orbital periods &lt; 200 yr). The steady-state population of HT comets is a complex function of the influx rate of new comets, the probability of capture and their physical lifetimes. From the discovery rate of active HT comets, their total population can be estimated to be of a few hundreds for perihelion distancesq &lt;2 AU. Randomly-oriented LP comets captured into short-period orbits (orbital periods &lt; 20 yr) show dynamical properties that do not match the observed properties of JF comets, in particular the distribution of their orbital inclinations, so Oort cloud comets can be ruled out as a suitable source for most JF comets. The scope of this presentation is to review the capture process of new comets into HT and short-period orbits, including the possibility that some of them may become sungrazers during their dynamical evolution.

scholarly journals Dynamics and orbital evolution of Oort cloud comets

1996 ◽  
Vol 172 ◽  
pp. 209-212 ◽  
Author(s):  
J.Q. Zheng ◽  
M.J. Valtonen ◽  
S. Mikkola ◽  
H. Rickman
Keyword(s):  
Solar System ◽  
Orbital Evolution ◽  
Oort Cloud ◽  
Long Period ◽  
Gravitational Perturbations ◽  
Short Period ◽  
Orbital Periods

Investigators generally conjecture a steady flux of new comets from the Oort cloud through the inner Solar system. Due to gravitational perturbations by major planets these objects may escape, become long period comets (LPCs) if their orbital periods P are larger than 200yr or become short period comets (SPCs) when their period is less than 200yr. SPCs are further divided in two types: the Halley type comets (HT, for P > 20yr) and the Jupiter family comets (JF, for P < 20yr).

scholarly journals Near-Earth objects from the cometary flux

2012 ◽  
Vol 10 (H16) ◽  
pp. 153-153
Author(s):  
Vacheslav Emel'yanenko
Keyword(s):  
Solar System ◽  
Outer Solar System ◽  
High Eccentricity ◽  
Earth Space ◽  
Near Earth Space ◽  
Dynamical Characteristics ◽  
Short Period ◽  
Near Earth Objects

AbstractWe analyze the orbital distribution of objects captured to near-Earth space from the flux of comets coming from the outer Solar system. For this purpose, we use the model of the cometary cloud developed earlier (Emelfyanenko, Asher, Bailey, 2007). This model is consistent with the broad dynamical characteristics of observed near-parabolic comets, short-period comets, Centaurs and high-eccentricity trans-Neptunian objects. We show that the observed distributions of both large and small near-Earth objects are different from the modeled distribution formed dynamically by the action of planetary perturbations. In particular, while the distributions of arguments of perihelion for observed Jupiter-family comets and modeled cometary asteroids follow a sinusoidal law with pronounced maxima around 0 and 180 degrees, it is not the case for observed cometary asteroids of any size. We conclude that there exist many unobserved extinct short-period comets among near-Earth objects of various sizes.

scholarly journals Physical and Dynamical Evolution of Long-Period Comets

1979 ◽  
Vol 81 ◽  
pp. 277-282 ◽  
Author(s):  
Paul R. Weissman
Keyword(s):  
Solar System ◽  
Dynamical Evolution ◽  
Oort Cloud ◽  
Observational Evidence ◽  
General Shape ◽  
Long Period ◽  
Spherical Cloud ◽  
Large Spike ◽  
Large Spherical

Oort (1950) first suggested that the source of the long-period comets is a large spherical cloud of comets surrounding the solar system and extending roughly halfway to the nearest stars. The observational evidence for this is the distribution of original inverse semi-major axes of the long-period comets which shows a large spike of comets at very small positive values of 1/ao, less than 10−4 AU−1. Attempts to model the evolution of these comets by Oort in his original paper, by Kendall (1961), Shteins (1961), and Whipple (1962) were successful in recreating the general shape of the 1/ao distribution. However in each case the authors were unable to match the observed ratio of new comets from the Oort cloud versus older comets evolving under the influence of planetary perturbations.

scholarly journals Spectroscopic and dynamical properties of comet C/2018 F4, likely a true average former member of the Oort cloud

2019 ◽  
Vol 625 ◽  
pp. A133 ◽  
Author(s):  
J. Licandro ◽  
C. de la Fuente Marcos ◽  
R. de la Fuente Marcos ◽  
J. de León ◽  
M. Serra-Ricart ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Visible Region ◽  
Dynamical Evolution ◽  
Visible Spectrum ◽  
Absolute Magnitude ◽  
Orbital Evolution ◽  
Oort Cloud ◽  
Chemical Compositions ◽  
Highly Active ◽  
Cometary Activity

Context. The population of comets hosted by the Oort cloud is heterogeneous. Most studies in this area have focused on highly active objects, those with small perihelion distances or examples of objects with peculiar physical properties and/or unusual chemical compositions. This may have produced a biased sample of Oort cloud comets in which the most common objects may be rare, particularly those with perihelia well beyond the orbit of the Earth. Within this context, the known Oort cloud comets may not be representative of the full sample meaning that our current knowledge of the appearance of the average Oort cloud comet may not be accurate. Comet C/2018 F4 (PANSTARRS) is an object of interest in this regard. Aims. Here, we study the spectral properties in the visible region and the cometary activity of C/2018 F4, and we also explore its orbital evolution with the aim of understanding its origin within the context of known minor bodies moving along nearly parabolic or hyperbolic paths. Methods. We present observations obtained with the 10.4 m Gran Telescopio Canarias (GTC) that we use to derive the spectral class and visible slope of C/2018 F4 as well as to characterise its level of cometary activity. Direct N-body simulations are carried out to explore its orbital evolution. Results. The absolute magnitude of C/2018 F4 is Hr > 13.62 ± 0.04 which puts a strong limit on its diameter, D < 10.4 km, assuming a pV = 0.04 cometary-like value of the albedo. The object presents a conspicuous coma, with a level of activity comparable to those of other comets observed at similar heliocentric distances. Comet C/2018 F4 has a visible spectrum consistent with that of an X-type asteroid, and has a spectral slope S′ = 4.0 ± 1.0%/1000 Å and no evidence of hydration. The spectrum matches those of well-studied primitive asteroids and comets. The analysis of its dynamical evolution prior to discovery suggests that C/2018 F4 is not of extrasolar origin. Conclusions. Although the present-day heliocentric orbit of C/2018 F4 is slightly hyperbolic, both its observational properties and past orbital evolution are consistent with those of a typical dynamically old comet with an origin in the Oort cloud.

scholarly journals First stars that could significantly perturb comet motion are finally found.

2019 ◽  
Author(s):  
Rita Wysoczańska ◽  
Piotr A Dybczyński ◽  
Małgorzata Królikowska
Keyword(s):  
Solar System ◽  
Dynamical Evolution ◽  
The Sun ◽  
First Stars ◽  
Multiple Systems ◽  
Long Period ◽  
Galactic Potential ◽  
Gaia Dr2 ◽  
Stellar Passages ◽  
Stellar Perturbations

Abstract Since 1950 when Oort published his paper on the structure of the cloud of comets it is believed that stars passing near this hypothetical cometary reservoir play an important role in the dynamical evolution of long period comets and injecting them into the observability region of the Solar System. The aim of this paper is to discuss two cases in which the data obtained from observations were used and stellar perturbations (of different intensity, strong case of C/2002 A3 LINEAR and weaker case of C/2013 F3 PANSTARRS) on cometary motion were detected. Using the best available data from the Gaia DR2 catalogue and some other sources we searched for close stellar passages near the Sun. Our study took into account that some of the stars are parts of multiple systems. Over 600 stars or systems that approached or will approach the Sun closer than 4.0 pc were found. Having the list of perturbers completed we studied their influence on a sample of 277 Oort spike comets that were observed since 1901 and discovered that two comets might have their orbits fundamentally changed due to a close stellar encounter. Our results show how much different the dynamical evolution of comets would have looked when their motion was considered only in the Galactic potential. Uncertainties both in stellar and cometary data were carefully taken into account. Our analysis indicates that the occurrence of stellar perturbations on cometary motions is very rare and the uncertainties of these effects are hard to estimate.

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