Dynamical evolution of C/2017 K2 PANSTARRS (original) (raw)
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The Influence Of Individual Stars On The long-Term Dynamics Of Comets C/2014 UN271 And C/2017 K2
Astronomy & Astrophysics
Context. In June 2021, the discovery of an unusual comet C/2014 UN271 (Bernardinelli-Bernstein) was announced. Its cometary activity beyond the orbit of Uranus has also refreshed interest in similar objects, including C/2017 K2 (PANSTARRS). Another peculiarity of these objects is the long interval of positional data, taken at large heliocentric distances. Aims. These two comets are suitable candidates for a detailed investigation of their long-term motion outside the planetary zone. Using the carefully selected orbital solutions, we aim to estimate the orbital parameters of their orbits at the previous perihelion passage. This might allow us to discriminate between dynamically old and new comets. Methods. To follow the dynamical evolution of long-period comets far outside the planetary zone, it is necessary to take into account both the perturbation caused by the overall Galactic gravitational potential and the actions of individual stars appearing in the solar neighborhood. To this...
Dynamics and orbital evolution of Oort cloud comets
Symposium - International Astronomical Union
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…
Long-term evolution of Oort Cloud comets: methods and comparisons
Monthly Notices of the Royal Astronomical Society, 2001
Two long-term simulation methods for cometary orbits, a Monte Carlo method and a direct integration method, are compared with each other. The comparison is done in seven inclination and perihelion distance intervals, and shows differences in dynamical lifetime and capture probabilities for the following main reasons. We use a finite energy step approximation in the Monte Carlo method and the method considers only close approaches with the planets. The differences can be taken into account statistically and it is possible to calculate the correction factors for the capture probability and dynamical lifetime in the Monte Carlo method. Both corrections depend on the inclination and on the value of the minimum energy step. The capture probabilities of the short-period comets originating in the Oort Cloud are calculated by the corrected Monte Carlo method and compared with published results.
The catalogue of cometary orbits and their dynamical evolution
Astronomy & Astrophysics
We present the CODE catalogue, the new cometary catalogue containing data for almost 300 long-period comets that were discovered before 2018. This is the first catalogue containing cometary orbits in the five stages of their dynamical evolution and covering three successive passages through the perihelion, with the exception of the hyperbolic comets which are treated in a different manner. Non-gravitational orbits are given for about 100 of these long-period comets, and their orbits obtained while neglecting the existence of non-gravitational acceleration are included for comparison. For many of the presented comets, different orbital solutions, based on the alternative force models or various subsets of positional data, are also provided. The preferred orbit is always clearly indicated for each comet.
Warsaw Catalogue of cometary orbits: 119 near-parabolic comets
Astronomy & Astrophysics, 2014
Context. The dynamical evolution of near-parabolic comets strongly depends on the starting values of the orbital elements derived from the positional observations. In addition, when drawing conclusions about the origin of these objects, it is crucial to control the uncertainties of orbital elements at each stage of the dynamical evolution. Aims. I apply a completely homogeneous approach to determine the cometary orbits and their uncertainties. The resulting catalogue is suitable for the investigation of the origin and future of near-parabolic comets. Methods. First, osculating orbits were determined on the basis of positional data. Second, the dynamical calculations were performed backwards and forwards up to 250 au from the Sun to derive original and future barycentric orbits for each comet. In the present investigation of dynamical evolution, the numerical calculations for a given object start from the swarm of virtual comets constructed using the previously determined osculating (nominal) orbit. In this way, the uncertainties of orbital elements were derived at the end of numerical calculations. Results. Homogeneous sets of orbital elements for osculating, original and future orbits are given. The catalogue of 119 cometary orbits constitutes about 70 per cent of all the first class so-called Oort spike comets discovered during the period 1801−2010 and about 90 per cent of those discovered in 1951−2010, for which observations were completed at the end of 2013. Non-gravitational (NG) orbits are derived for 45 comets, including asymmetric NG solution for six of them. Additionally, the new method for cometary orbit-quality assessment is applied for all these objects.
New orbit recalculations of comet C/1890 F1 Brooks and its dynamical evolution
Monthly Notices of the Royal Astronomical Society
C/1890 F1 Brooks belongs to a group of nineteen comets used by Jan Oort to support his famous hypothesis on the existence of a spherical cloud containing hundreds of billions of comets with orbits of semimajor axes between 50 and 150 thousand au. Comet Brooks stands out from this group because of a long series of astrometric observations as well as nearly two-year long observational arc. Rich observational material makes this comet an ideal target for testing the rationality of an effort to recalculate astrometric positions on the basis of original (comet-star)-measurements using modern star catalogues. This paper presents the results of such new analysis based on two different methods: (i) automatic re-reduction based on cometary positions and the (comet-star)-measurements, and (ii) partially automatic re-reduction based on the contemporary data for originally used reference stars. We show that both methods offer a significant reduction of orbital elements uncertainties. Based on the most preferred orbital solution, the dynamical evolution of comet Brooks during three consecutive perihelion passages is discussed. We conclude that C/1890 F1 is a dynamically old comet that passed the Sun at a distance below 5 au during its previous perihelion passage. Furthermore, its next perihelion passage will be a little closer than during the 1890-1892 apparition. C/1890 F1 is interesting also because it suffered extremely small planetary perturbations when it travelled through the planetary zone. Therefore, in the next passage through perihelion it will be once again a comet from the Oort spike.
Where do long-period comets come from? 26 comets from the non-gravitational Oort spike
Monthly Notices of the Royal Astronomical Society, 2010
Since 1950, when Oort published his hypothesis, several important new facts have been established in this field. At present, there are still questions surrounding the apparent source region (or regions) of long-period comets, the definition of dynamically new comets and the characteristics of the hypothetical Oort Cloud. Our aim in this investigation is to look for the apparent source of selected long-period comets and to refine the definition of dynamically new comets. Based on pure gravitational original orbits, all comets studied in this paper are widely called dynamically new. However, we show that the incorporation of non-gravitational forces into the orbit determination process significantly changes the situation. We have determined the precise non-gravitational orbits of all investigated comets. Then, we have followed numerically their past and future motions during one orbital period. Applying the ingenious method of Sitarski of creating swarms of virtual comets compatible with observations, we have been able to derive the uncertainties of original and future orbital elements, as well as the uncertainties of previous and next perihelion distances. We conclude that the past and future evolutions of cometary orbits under Galactic tide perturbations is the only way to find which comets are really dynamically new. In our sample, fewer than 30 per cent of comets are, in fact, dynamically new. Most of these have small previous perihelion distances. However, 60 per cent of these will be lost on hyperbolic orbits in the future. This evidence suggests that the investigation into the apparent source of longperiod comets is challenging. We have also shown that a significant percentage of long-period comets can visit the zone of visibility during at least two or three consecutive perihelion passages.
Monthly Notices of the Royal Astronomical Society, 2013
Dynamics of a complete sample of small perihelion distance near-parabolic comets discovered in the years 2006-2010 are studied (i.e. of 22 comets of q osc < 3.1 au). First, osculating orbits are obtained after a very careful positional data inspection and processing, including where appropriate, the method of data partitioning for determination of pre-and post-perihelion orbit for tracking then its dynamical evolution. The non-gravitational acceleration in the motion is detected for 50 per cent of investigated comets, in a few cases for the first time. Different sets of non-gravitational parameters are determined from preand post-perihelion data for some of them. The influence of the positional data structure on the possibility of the detection of non-gravitational effects and the overall precision of orbit determination is widely discussed. Secondly, both original and future orbits were derived by means of numerical integration of swarms of virtual comets obtained using a Monte Carlo cloning method. This method allows us to follow the uncertainties of orbital elements at each step of dynamical evolution. The complete statistics of original and future orbits that includes significantly different uncertainties of 1/avalues is presented, also in the light of our results obtained earlier. Basing on 108 comets examined by us so far, we conclude that only one of them, C/2007 W1 Boattini, seems to be a serious candidate for an interstellar comet. We also found that 53 per cent of 108 nearparabolic comets escaping in the future from the Solar system, and the number of comets leaving the Solar system as so called Oort spike comets (i.e. comets suffering very small planetary perturbations) is 14 per cent. A new method for cometary orbit quality assessment is also proposed by means of modifying the original method, introduced by Marsden, Sekanina & Everhart. This new method leads to a better diversification of orbit quality classes for contemporary comets.
Different dynamical histories for comets C/2001 Q4 and C/2002 T7?
Astronomy & Astrophysics, 2012
Context. Both, C/2001 Q4 and C/2002 T7, are widely regarded in the literature as dynamically new comets that are visiting our planetary system for the first time from the Oort Cloud. Aims. We study the past dynamical evolution of these two bright comets that both have an original semimajor axis inside the so-called Oort spike (i.e. with 1/a ori < 10 −4 AU −1). Methods. For each comet, we constructed a dedicated grid of independent, starting, osculating swarms of 5000 orbits based on different subsets of positional data and different dependences of the non-gravitational acceleration on the heliocentric distance. We then followed numerically each swarm of non-gravitational orbits one orbital revolution into the past, taking into account both planetary and Galactic perturbations and checking for all known stellar perturbers. This method allows us to obtain the orbital elements and their uncertainties at the previous perihelion passage. Results. We find that the dedicated g(r)-like function seems to be more adequate for describing the non-gravitational effects than the standard g(r)-function in the motion of both comets, but we are able to estimate only two parameters: the scale distance r 0 , and the exponent m. We show, however, that the greatest change in the previous perihelion value relative to that obtained in the standard approach results from the type of data subset used for non-gravitational orbit determination. The form of the dependence of nongravitational acceleration on heliocentric distance is of secondary importance for both investigated comets in this context. We find that only comet C/2002 T7 passed far beyond the planetary system during its previous perihelion passage and that C/2001 Q4 was probably well inside the Saturn orbit at a previous perihelion. Conclusions. We argue that for these comets (which have long sequences of positional data), the safest method for the previous perihelion determination is to exclude data within time intervals where some local outbursts were reported. We recommend that the non-gravitational models based on data taken at larger perihelion distance are more appropriate for estimating the distance of previous perihelion passage of C/2001 Q4 and those based on a pre-perihelion data set for previous perihelion estimation of C/2002 T7. These models suggest that C/2001 Q4 passed its previous perihelion closer than 6-7 AU from the Sun, so is dynamically old, whereas C/2002 T7 at a distance larger than 400 AU, is a dynamically new comet since it overcame the Jupiter-Saturn barrier.
Oort spike comets with large perihelion distances
Monthly Notices of the Royal Astronomical Society, 2017
The complete sample of large-perihelion nearly-parabolic comets discovered during the period 1901-2010 is studied, starting with their orbit determination. Next, an orbital evolution that includes three perihelion passages (previous-observed-next) is investigated in which a full model of Galactic perturbations and perturbations from passing stars is incorporated. We show that the distribution of planetary perturbations suffered by actual large-perihelion comets during their passage through the Solar system has a deep, unexpected minimum around zero, which indicates a lack of 'almost unperturbed' comets. Using a series of simulations we show that this deep well is moderately resistant to some diffusion of the orbital elements of the analysed comets. It seems reasonable to assert that the observed stream of these largeperihelion comets experienced a series of specific planetary configurations when passing through the planetary zone. An analysis of the past dynamics of these comets clearly shows that dynamically new comets can appear only when their original semimajor axes are greater than 20 000 au. On the other hand, dynamically old comets are completely absent for semimajor axes longer than 40 000 au. We demonstrate that the observed 1/a ori-distribution exhibits a local minimum separating dynamically new from dynamically old comets. Long-term dynamical studies reveal a wide variety of orbital behaviour. Several interesting examples of the action of passing stars are also described, in particular the impact of Gliese 710, which will pass close to the Sun in the future. However, none of the obtained stellar perturbations is sufficient to change the dynamical status of the analysed comets.