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

Author(s):  
Rita Wysoczańska ◽  
Piotr A Dybczyński ◽  
Małgorzata Królikowska

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.

2006 ◽  
Vol 2 (S236) ◽  
pp. 43-54 ◽  
Author(s):  
Olga A. Mazeeva

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.


2016 ◽  
Vol 12 (S325) ◽  
pp. 263-265
Author(s):  
Rustam Guliyev ◽  
Ayyub Guliyev

AbstractIn the present work we investigate the possible relationship of long-period comets with five large and distant trans-Neptunian bodies (Sedna, Eris, 2007 OR10, 2012 VP113and 2008 ST291) in order to determine the probability of the transfer of a part of these kind of comets to the inner of the Solar System. To identify such relationships, we studied the relative positions of the comet orbits and listed TNOs. Using numerical integration methods, we examined dynamical evolution of the comets and have found one encounter of comet C/1861J1 and Eris.


2020 ◽  
Author(s):  
Youssef Moulane ◽  
Emmanuel Jehin ◽  
Francisco José Pozuelos ◽  
Jean Manfroid ◽  
Zouhair Benkhaldoun ◽  
...  

&lt;p&gt;Long Period Comets (LPCs) have orbital periods longer than 200 years, perturbed from their resting place in the Oort cloud. Such gravitational influences may send these icy bodies on a path towards the center of the Solar system in highly elliptical orbits. In this work, we present the activity and composition evolution of several LPCs observed with both TRAPPIST telescopes (TS and TN) during the period of 2019-2020. These comets include: C/2017 T2 (PANSTARRS), C/2018 Y1 (Iwamoto), C/2018 W2 (Africano), and disintegrated comet C/2019 Y4 (ATLAS). We monitored the OH, NH, CN, C&lt;sub&gt;2&lt;/sub&gt; and C&lt;sub&gt;3&lt;/sub&gt; production rates evolution and their chemical mixing ratios with respect to their distances to the Sun as well as the dust production rate proxy (A(0)fp) during the journey of these comets into the inner Solar system.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;C/2017 T2 (PANSTARRS)&lt;/strong&gt; is a very bright comet which was discovered on October 2, 2017 when it was 9.20 au from the Sun. We started observing this comet with TS at the beginning of August 2019 when it was at 3.70 au. The comet made the closest approach to the Earth on December 28, 2019 at a distance of 1.52 au and it passed the perihelion on May 4, 2020 at 1.61 au. The water production rate of the comet reached a maximum of (4,27&amp;#177;0,12)10&lt;sup&gt;28 &lt;/sup&gt;molecules/s and its dust production rate (A(0)fp(RC)) also reached the peak of 5110&amp;#177;25 cm on January 26, 2020, when the comet was at 2.08 au from the Sun (-100 days pre-perihelion). At the time of writing, we still monitoring the activity of the comet with TN at heliocentric distance of 1.70 au. Our observations show that C/2017 T2 is a normal LPC.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;C/2018 Y1 (Iwamoto)&lt;/strong&gt; is a nearly parabolic comet with a retrograde orbit discovered on December 18, 2018 by Japanese amateur astronomer Masayuki Iwamoto. We monitored the activity and composition of Iwamoto with both TN and TS telescopes from January to March 2019. The comet reached its maximum activity on January 29, 2019 when it was at 1.29 au from the Sun (-8 days pre-perihelion) with Q(H&lt;sub&gt;2&lt;/sub&gt;O)=(1,68&amp;#177;0,05)10&lt;sup&gt;28 &lt;/sup&gt;molecules/s and A(0)fp(RC)= 92&amp;#177;5 cm. These measurements show that it was a dust-poor comet compared to the typical LPCs.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;C/2018 W2 (Africano) &lt;/strong&gt;was discovered on November 27, 2018 at Mount Lemmon Survey with a visual magnitude of 20. The comet reached its perihelion on September 6, 2019 when it was at 1.45 au from the Sun. We monitored the comet from July 2019 (r&lt;sub&gt;h&lt;/sub&gt;=1.71 au) to January 2020 (r&lt;sub&gt;h&lt;/sub&gt;=2.18 au) with both TN and TS telescopes. The comet reached its maximum activity on September 21, 15 days post-perihelion (r&lt;sub&gt;h&lt;/sub&gt;=1.47 au) with Q(H&lt;sub&gt;2&lt;/sub&gt;O)=(0,40&amp;#177;0,03)10&lt;sup&gt;28 &lt;/sup&gt;molecules/s.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;C/2019 Y4 (ATLAS)&lt;/strong&gt; is a comet with a nearly parabolic orbit discovered on December 18, 2019 by the ATLAS survey. We started to follow its activity and composition with broad- and narrow-band filters with the TN telescope on February 22, 2019 when it was at 1.32 au from the Sun until May 3, 2020 when the comet was at a heliocentric distance of 0.90 au inbound. The comet activity reached a maximum on March 22 (r&lt;sub&gt;h&lt;/sub&gt;=1.65 au) 70 days before perihelion. At that time, the water-production rate reached (1,53&amp;#177;0,04)10&lt;sup&gt;28 &lt;/sup&gt;molecules/s and the A(0)fp reached (1096&amp;#177;14) cm in the red filter. After that, the comet began to fade and disintegrated into several fragments.&lt;/p&gt;


2015 ◽  
Vol 112 (14) ◽  
pp. 4214-4217 ◽  
Author(s):  
Konstantin Batygin ◽  
Greg Laughlin

The statistics of extrasolar planetary systems indicate that the default mode of planet formation generates planets with orbital periods shorter than 100 days and masses substantially exceeding that of the Earth. When viewed in this context, the Solar System is unusual. Here, we present simulations which show that a popular formation scenario for Jupiter and Saturn, in which Jupiter migrates inward from a > 5 astronomical units (AU) to a ≈ 1.5 AU before reversing direction, can explain the low overall mass of the Solar System’s terrestrial planets, as well as the absence of planets with a < 0.4 AU. Jupiter’s inward migration entrained s ≳ 10−100 km planetesimals into low-order mean motion resonances, shepherding and exciting their orbits. The resulting collisional cascade generated a planetesimal disk that, evolving under gas drag, would have driven any preexisting short-period planets into the Sun. In this scenario, the Solar System’s terrestrial planets formed from gas-starved mass-depleted debris that remained after the primary period of dynamical evolution.


2019 ◽  
Vol 489 (1) ◽  
pp. 951-961 ◽  
Author(s):  
C de la Fuente Marcos ◽  
R de la Fuente Marcos

ABSTRACT The chance discovery of the first interstellar minor body, 1I/2017 U1 (‘Oumuamua), indicates that we may have been visited by such objects in the past and that these events may repeat in the future. Unfortunately, minor bodies following nearly parabolic or hyperbolic paths tend to receive little attention: over 3/4 of those known have data-arcs shorter than 30 d and, consistently, rather uncertain orbit determinations. This fact suggests that we may have observed interstellar interlopers in the past, but failed to recognize them as such due to insufficient data. Early identification of promising candidates by using N-body simulations may help in improving this situation, triggering follow-up observations before they leave the Solar system. Here, we use this technique to investigate the pre- and post-perihelion dynamical evolution of the slightly hyperbolic comet C/2018 V1 (Machholz–Fujikawa–Iwamoto) to understand its origin and relevance within the context of known parabolic and hyperbolic minor bodies. Based on the available data, our calculations suggest that although C/2018 V1 may be a former member of the Oort Cloud, an origin beyond the Solar system cannot be excluded. If extrasolar, it might have entered the Solar system from interstellar space at low relative velocity with respect to the Sun. The practical feasibility of this alternative scenario has been assessed within the kinematic context of the stellar neighbourhood of the Sun, using data from Gaia second data release, and two robust solar sibling candidates have been identified. Our results suggest that comets coming from interstellar space at low heliocentric velocities may not be rare.


1985 ◽  
Vol 83 ◽  
pp. 31-41
Author(s):  
W.M. Napier

AbstractThe effects of encounters with massive nebulae on the long-period comet population are examined, paying particular attention to the uncertainties in the data. An earlier conclusion, that the long-period comet system is dynamically unstable, is upheld. Whether replenishment by unbinding from a dense inner comet cloud is a viable hypothesis awaits detailed modelling, but a qualitative discussion is given which argues tentatively against it. If comets occur in molecular clouds, however, their capture into temporarily bound Solar System orbits is a natural consequence of close encounters for realistic velocities and potentials. A large disturbance or capture may have occurred a few Myr ago as the Sun emerged from the Orion spiral arm.


2019 ◽  
Vol 627 ◽  
pp. A119 ◽  
Author(s):  
R. Carrera ◽  
M. Pasquato ◽  
A. Vallenari ◽  
L. Balaguer-Núñez ◽  
T. Cantat-Gaudin ◽  
...  

Context. NGC 2682 is a nearby open cluster that is approximately 3.5 Gyr old. Dynamically, most open clusters are expected to dissolve on shorter timescales of ≈1 Gyr. That it has survived until now means that NGC 2682 was likely much more massive in the past and is bound to have an interesting dynamical history. Aims. We investigate the spatial distribution of the stars in NGC 2682 to constrain dynamical evolution of the cluster. We particularly focus on the marginally bound stars in the cluster outskirts. Methods. We used Gaia DR2 data to identify NGC 2682 members up to a distance of ∼150 pc (10°). The two methods Clusterix and UPMASK were applied to this end. We estimated distances to obtain 3D stellar positions using a Bayesian approach to parallax inversion, with an appropriate prior for star clusters. We calculated the orbit of NGC 2682 using the GRAVPOT16 software. Results. The cluster extends up to 200′ (50 pc), which implies that its size is at least twice as large as previously believed. This exceeds the cluster Hill sphere based on the Galactic potential at the distance of NGC 2682. Conclusion. The extra-tidal stars in NGC 2682 may originate from external perturbations such as disc-shocking or dynamical evaporation from two-body relaxation. The former origin is plausible given the orbit of NGC 2682, which crossed the Galactic disc ≈40 Myr ago.


2018 ◽  
Vol 615 ◽  
pp. A170 ◽  
Author(s):  
Małgorzata Królikowska ◽  
Piotr A. Dybczyński

Context. The comet C/2017 K2 PANSTARRS drew attention to its activity at the time of its discovery in May 2017 when it was about 16 au from the Sun. This Oort spike comet will approach its perihelion in December 2022, and the question about its dynamical past is an important issue to explore. Aims. In order to answer the question of whether C/2017 K2 is a dynamically old or new comet it is necessary to obtain its precise osculating orbit, its original orbit, and propagate its motion backwards in time to the previous perihelion. Knowledge of the previous perihelion distance is necessary to distinguish between these two groups of the Oort spike comets. We have studied the dynamical evolution of C/2017 K2 to the previous perihelion (backward calculations for about 3–4 Myr) as well as to the future (forward calculations for about 0.033 Myr) using the swarm of virtual comets (VCs) constructed from a nominal osculating orbit of this comet which we determined here using all positional measurements available at the moment. Outside the planetary system both Galactic and stellar perturbations were taken into account. Results. We derive that C/2017 K2 is a dynamically old Oort spike comet (1/aprev = (48.7 ± 7.9) × 10−6 au−1) with the previous perihelion distance below 10 au for 97% of VCs (nominal qprev = 3.77 au). According to the present data this comet will be perturbed into a more tightly bound orbit after passing the planetary zone (1/afut = (1140.4 ± 8.0) × 10−6 au−1, qfut = 1.79336 ± 0.00006 au) provided that non-gravitational effects will not change the orbit significantly. Conclusions. C/2017 K2 has already visited our planetary zone during its previous perihelion passage. Thus, it is almost certainly a dynamically old Oort spike comet. The future orbital solution of this comet is formally very precise, however, it is much less definitive since the presented analysis is based on pre-perihelion data taken at very large heliocentric distances (23.7–14.6 au from the Sun), and this comet can experience a significant non-gravitational perturbation during the upcoming perihelion passage in 2022.


1976 ◽  
Vol 25 (Part1) ◽  
pp. 445-464 ◽  
Author(s):  
Edgar Everhart

AbstractThis review states and defends seven conclusions on the origin of comets and the evolution of their orbits:1.There is a N-½ law of survival of comets against ejection on hyperbolic orbits, where N is the number of perihelion passages.2.The short-period comets are not created by single close encounters of near-parabolic comets with Jupiter.3.Observable long-period comets do not evolve into observable short-period comets.4.Unobservable long-period comets with perihelia near Jupiter can evolve into observable short-period comets.5.Long-period comets cannot have been formed or created within the planetary region of the solar system. (This conclusion is somewhat qualified because of possible effects of stellar perturbations. )6.It is possible that some of ths short-period comets could have been formed inside the orbit of Neptune, but it is certain that others have the same distant source as the long-period comets.7.The circularly-restricted 3-body problem, and its associated Jacobi integral, are not valid approximations to use in studying origin and evolution of comets.


2009 ◽  
Vol 5 (S263) ◽  
pp. 57-66 ◽  
Author(s):  
Marc Fouchard

AbstractThe Oort cloud, which corresponds to the furthest boundary of our Solar System, is considered as the main reservoir of long period comets. This cloud is likely a residual of the Solar System formation due to the gravitational effects of the young planets on the remaining planetesimals. Given that the cloud extends to large distances from the Sun (several times 10 000 AU), the bodies in this region have their trajectories affected by the Galactic environment of the Solar System. This environment is responsible for the re-injection of the Oort cloud comets into the planetary region of the Solar System. Such comets, also called “new comets”, are the best candidates to become Halley type or “old” long period comets under the influence of the planetary gravitational attractions. Consequently, the flux of new comets represents the first stage of the long trip from the Oort cloud to the observable populations of comets. This is why so many studies are still devoted to this flux.The different perturbers related to the Galactic environment of the Solar System, which have to be taken into account to explain the flux are reviewed. Special attention will be paid to the gravitational effects of stars passing close to the Sun and to the Galactic tides resulting from the difference of the gravitational attraction of the Galaxy on the Sun and on a comet. The synergy which takes place between these two perturbers is also described.


Sign in / Sign up

Export Citation Format

Share Document