arXiv subjects

Piotr A. Dybczyński

Publications and source records attributed to Piotr A. Dybczyński.

At least 19 recordsLinked to original sources

arXiv2025

Update of the CODE catalogue and some aspects of the dynamical status of Oort Cloud comets

The outer Solar System is believed to host a vast reservoir of long-period comets (LPCs), but our understanding of their spatial distribution and dynamical history remains limited due to observational biases and uncertainties in orbital solutions for really observed comets. We aim to provide a comprehensive and dynamically homogeneous orbital database of LPCs to support the study of their origin, evolution, dynamical status, and 6D distribution of orbital elements. We updated the Catalogue of Cometary Orbits and their Dynamical Evolution (CODE catalogue) by computing original and future barycentric orbits, orbital parameters at previous and next perihelion, using full Monte Carlo swarms of real comets for the uncertainty estimation and taking into account the planetary, Galactic and passing stars perturbations according to the latest data and algorithms. This update of the CODE catalogue focuses on the dynamical status of near-parabolic comets. Using current stellar data, we formulated new constraints for dynamically new comets. Now, the CODE database includes 983 orbital solutions for 369 comets with full uncertainty estimates and dynamical classifications, covering nearly all comets with original semi-major axes exceeding 10,000\,au and discovered before 2022, as well as all LPCs discovered beyond 10\,au from the Sun during this period, and over 80\% of the known LPCs with perihelion distances beyond 7\,au.

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arXiv2024

HD 7977 and its possible influence on Solar System bodies

In the latest Gaia third data release one can find extremely small proper motion components for the star HD 7977. This, together with the radial velocity measurement lead to the conclusion that this star passed very close to the Sun in the recent past. Such a very close approach of a one solar mass star must result in noticeable changes in the motion of all Solar System bodies, especially those on less tight orbits, namely long-period comets (LPCs) and Kuiper belt objects. We estimate and present these effects. Our current knowledge on the stellar surroundings of the Sun found in the latest Gaia catalogues allowed us to perform numerical integrations and prepare a list of potential stellar perturbers of LPCs. We use this list, made available in the StePPeD database. To study the past motion of LPCs under the simultaneous action of the Galactic potential and passing stars, we use precise original cometary orbits taken from the current CODE catalogue. We examine the reliability of the extremely small proper motion of HD 7977 concluding that this star can be an unresolved binary but according to the astrometry covering more than a century, the current Gaia results cannot be ruled out. We present the parameters of a very close passage of this star near the Sun. We also show examples of the strong influence of this passage on the past motion of some LPCs. We also discuss the possible influence of this perturber on other Solar System bodies. It is possible that 2.47 Myr ago the one solar mass star HD 7977 passed as close as one thousand au from the Sun. Such an event constitutes a kind of dynamical horizon for all studies of the past Solar System bodies' dynamics.

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arXiv2023

News in the CODE Catalogue

We describe here updates and new elements of the Catalogue of Cometary Orbits and their Dynamical Evolution (CODE) that, in its original 2020 version, has been introduced by Królikowska & Dybczyński (2020). Currently, the CODE Catalogue offers rich sets of orbital solutions for almost a complete sample of Oort spike comets discovered between 1900 and 2021. We often offer several orbital solutions based on different nongravitational force models or different observational material treatments. An important novelty is that the `previous` (at previous perihelion or at 120,000 au from the Sun in the past) and `next` (at next perihelion or 120,000 au after leaving the planetary zone) orbits are given in two variants. One with the dynamical model restricted only to the full Galactic tide (with all individual stars omitted) and the second one, where all currently known stellar perturbers are also taken into account. Calculations of the previous and next orbits were performed using the up-to-date StePPeD database of potential stellar perturbers.

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arXiv2022

Important stellar perturbers found during the StePPeD database update based on Gaia EDR3 data

Context. In 2020, the initial version of the Stellar Potential Perturbers Database (StePPeD) was presented with the aim to deliver up-to-date information on the stars and stellar systems that may perturb a long-period comet motion. We used the minimal distance between a star and the Sun as a selecting tool when compiling a list of interesting objects with close encounters with the Solar System, and our selection for that study was based on Gaia DR2 data. Aims. When the Gaia EDR3 data release was published, it became necessary to update this database. Additionally, we performed Monte Carlo simulations to obtain uncertainties on the parameters of the closest approach to the Sun of each object. Methods. We recalculated the close approach parameters of all stars in the previous StePPeD release, which resulted in removing approximately one-third of the total. Then we searched for new candidates in the whole Gaia EDR3 catalogue. We also take into account the duplicity of the found stars and additionally searched for double stars passing near the Sun which had been overlooked in previous papers. We also found the necessary mass estimates for new objects and updated this information for previously selected stars. Results. After a careful checking of all the collected data, we composed a new list of 155 potential stellar perturbers of the long-period comet motion. We applied a new threshold of 2 pc for the minimum star-Sun distance. This list consists of 146 single stars and nine multiple systems. For each object, we also estimated the uncertainty of the parameters of their closest approach to the Sun. Among these stars, we found a new potential strong past perturber, HD 7977, and confirmed the plausibility of a similar action on the part of Gliese 710 in the future.

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arXiv2022

The influence of individual stars on the long-term dynamics of comets C/2014 UN271 and C/2017 K2

In June 2021 the discovery of an unusual comet C/2014 UN271 Bernardinelli-Bernstein has been announced. Its cometary activity beyond Uranus orbit also has refreshed interest in similar objects, including C/2017K2 PanSTARRS. Another peculiarity of these objects is the long interval of positional data, taken at large heliocentric distances. These two comets are suitable candidates for a detailed investigation of their long-term motion outside the planetary zone. Using the selected orbital solutions, we aim at estimating the orbital parameters of their orbits at the previous perihelion passage. This might allow us to discriminate between dynamically old and new comets. 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 aim, we applied the recently published methods based on stellar perturbers ephemerides. For C/2014 UN271 we obtained a precise orbital solution that can be propagated to the past and to the future. For C/2017 K2 we have to limit ourselves to study only the past motion since some signs of nongravitational effects can be found in recent positional observations. Therefore, we use a specially selected orbital solution suitable for past motion studies. Using these starting orbits, we propagated both comets to their previous perihelia. We also investigated the future motion of C/2014 UN271. Orbital evolution of these two comets appears to be sensitive to perturbations from several stars that closely approach the Sun. Unfortunately, some of these stars have 6D data with uncertainties too large to obtain definitive results for the studied comets; however, it appears that both comets were probably outside the planetary zone in the previous perihelion.

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arXiv2021

Galactic and stellar perturbations of long period comet motion -- Practical considerations

Context. Due to our increasing knowledge on the Galactic and stellar neighborhood of the Solar System, modern long-period comet motion studies have to take into account both stellar perturbations and the overall Galactic potential. Aims. Our aim is to propose algorithms and methods to perform numerical integration of a Solar System small body equations of motion much faster and at the same time with greater precision. Methods. We propose a new formulation of the equations of motion formulated in the Solar System barycentric frame but accurately accounting for the differential perturbations caused by the Galactic potential. To use these equations effectively we provide numerical ephemerides of the Galactic positions of the Sun and a set of potential stellar perturbers. Results. The proposed methods offer the precision higher by several orders of magnitude and simultaneously greatly reduce the necessary CPU time. The application of this approach is presented with the example of a detailed dynamical study of the past motion of comet C/2015 XY1.

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arXiv2020

The Catalogue of Cometary Orbits and their Dynamical Evolution

The new cometary catalogue containing data for almost 300 long-period comets that were discovered before 2018 is announced (the CODE catalogue). This is the first catalogue containing cometary orbits in five stages of their dynamical evolution, covering three successive passages through the perihelion, except the hyperbolic comets which are treated in a different manner. For about 100 of these long-period comets, their non-gravitational orbits are given, and for a comparison also their orbits obtained while neglecting the existence of non-gravitational acceleration are included. For many of the presented comets different orbital solutions, based on the alternative force models or various subsets of positional data are additionally given. The preferred orbit is always clearly indicated for each comet.

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arXiv2020

A surprise in the updated list of stellar perturbers of long period comets motion

The second Gaia data release (Gaia DR2) provided us with the precise five-parameter astrometry for 1.3 billion of sources. As stars passing close to the Solar System are thought to be responsible for influencing the dynamical history of long period comets, we update and extend the list of stars that could potentially perturb motion of these comets. We aim to announce a publicly available database containing an up to date list of stars and stellar systems potentially perturbing long period comets motion. We add new objects and revise previously published lists. Special emphasis was placed on stellar systems. Discussion on masses estimation is included. Using the astrometry, preferably from Gaia DR2, augmented with data from other sources, we calculate spatial positions and velocities for each star. To filter studied objects on the basis of their minimal heliocentric distances we numerically integrate motion of stars under the Galactic potential and their mutual interactions. We announce the updated list of stellar perturbers of cometary motion, including masses of perturbers along with the publicly available database interface. These data are ready to be used with the observed long period comets orbits to study an individual influence of a whole sample of perturbers, or specific stars, on a dynamical past or future of a specific comet. 147 new perturbers were added in comparison to the previously published sources. We demonstrate that a new set of potential perturbers constitute an important tool in studies of cometary dynamics. The usage of our data significantly changes results of the past and future comet motion analysis. We point out a puzzling object in our list, star ALS 9243. The Gaia DR2 astrometry suggests a very close encounter of this star with the Sun however, its astrophysical parameters result in a completely different current distance of ALS 9243 and its large mass.

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arXiv2019

Kruger 60 as a home system for 2I/Borisov -- a case study

For the second discovered interstellar comet 2I/Borisov we searched for a candidate for its home system. We will never be sure which star or stellar system does this comet come from but obtaining a very small relative velocity and a promisingly small miss-distance, when tracing the motion of 2I/Borisov back in time in its movement through the space, makes an encountered body a good candidate for a source of this comet. In our long-standing project on studying Oort spike comets dynamics, we recently updated a list of potential stellar perturbers of cometary motion. This list was checked against a past, close and slow encounter with 2I/Borisov. Only one object from among 647 stars or stellar systems in our list, a double star Kruger 60, appeared as a potential candidate for the origin of this comet. However, a detailed analysis of this system's radial velocity uncertainty influence on our result showed, that the probability that Kruger 60 is a home system of 2I/Borisov is small. Finally, the usage of a new, unpublished systemic radial velocity of Kruger 60 system practically ruled out this possibility.

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arXiv2019

First stars that could significantly perturb comet motion are finally found

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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arXiv2019

Discovery statistics and the 1/a-distribution of long-period comets detected over the 1801-2017 period

For the last two decades we have been observing a huge increase in discoveries of long-period comets (LPCs), especially those with large-perihelion distances. We collected data for a full sample of LPCs discovered over the 1801-2017 period including their osculating orbits, discovery moments (to study the discovery distances), and original semimajor axes (to study the number ratio of large-perihelion to small-perihelion LPCs in function of 1/a-original, and to construct the precise distribution of an 1/a-original). To minimize the influence of parabolic comets on these distributions we determined definitive orbits (which include eccentricities) for more than 20 LPCs previously classified as parabolic comets. We show that the percentage of large-perihelion comets is significantly higher within Oort spike comets than in a group of LPCs with a<10000 au, and this ratio of large-perihelion to small-perihelion comets for both groups has grown systematically since 1970. The different shape of the Oort spike for small-perihelion and large-perihelion LPCs is also discussed. A spectacular decrease of the ratio of large-perihelion to small-perihelion LPCs with the shortening of semimajor axis within the range of 5000-100 au is also noticed. Analysing discovery circumstances, we found that Oort spike comets are discovered statistically at larger geocentric and heliocentric distances than the remaining LPCs. This difference in the percentage of large-perihelion comets in both groups of LPCs can probably be a direct consequence of a well-known comets fading process due to ageing of their surface during the consecutive perihelion passages and/or reflects the different actual q-distributions.

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arXiv2018

Note on the dynamical evolution of C/2017 K2 PANSTARRS

(Abreviated) Comet C/2017 K2 PANSTARRS drew attention to its activity already at a 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 one of the important issues to explore. To this aim it is necessary to obtain its precise osculating orbit, its original orbit, and propagate its motion backwards in time to the previous perihelion. We study a 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). Outside the planetary system both Galactic and stellar perturbations were taken into account. We derived that C/2017 K2 is a dynamically old Oort spike comet (1/a$_{prev}$ = (48.7 $\pm$ 7,9) x10$^{-6}$ au$^{-1}$) with the previous perihelion distance below 10 au for 97 per cent of VCs (nominal q$_{prev}$ = 3.77 au). It means that 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.

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arXiv2018

Have we missed an interstellar comet four years ago?

New orbit for C/2014 W10 PANSTARRS is obtained. High original eccentricity of e = 1.65 might suggest an interstellar origin of this comet. The probable reasons for missing this possible important event is discussed and a call for searching potential additional observations in various archives is proposed.

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arXiv2018

On the dynamical history of the interstellar object 'Oumuamua?

1I/2017 U1 'Oumuamua is the first interstellar object recorded inside the Solar System. We try to answer the main question: where does it come from? To this aim we searched for close encounters between 'Oumuamua and all nearby stars with known kinematic data during their past motion.We had checked over 200 thousand stars and found just a handful of candidates. If we limit our investigation to within a 60 pc sphere surrounding the Sun, then the most probable candidate for the 'Oumuamua parent stellar habitat is the star UCAC4 535-065571. However GJ 876 is also a favourable candidate. Moreover, the origin of 'Oumuamua from a much more distant source is still an open question. Additionally, we found that the quality of the original orbit of 'Oumuamua is accurate enough for such a study and that none of the checked stars had perturbed its motion significantly. All numerical results of this research are available in the Appendix.

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arXiv2017

Oort spike comets with large perihelion distances

The complete sample of large-perihelion nearly-parabolic comets discovered during the period 1901-2010 is studied starting from their orbit determination. Next, an orbital evolution that includes three perihelion passages (previous-observed-next) is investigated where a full model of Galactic perturbations and perturbations from passing stars have been 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. By a series of simulations we show that this deep well is moderately resistant to some diffusion of orbital elements of analysed comets. It seems reasonable to state that the observed stream of these large-perihelion 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 may appear only when their original semimajor axes are greater than 20 000 au. However, only for semimajor axes longer than 40 000 au dynamically old comets are completely not present. We demonstrated that the observed $1/a_{\rm ori}$ distribution exhibits a local minimum separating dynamically new from dynamically old comets. Long-term dynamical studies reveal a large variety of orbital behaviour. Several interesting examples of 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 analysed comets.

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arXiv2016

New orbit recalculations of comet C/1890 F1 Brooks and its dynamical evolution

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.

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arXiv2015

On the accuracy of close stellar approaches determination

The aim of this paper is to demonstrate the accuracy of our knowledge of close stellar passage distances in the pre-GAIA era.We used the most precise astrometric and kinematic data available at the moment and prepared a list of 40 stars nominally passing (in the past or future) closer than 2 pc from the Sun.We used a full gravitational potential of the Galaxy to calculate the motion of the Sun and a star from their current positions to the proximity epoch. For this calculations we used a numerical integration in rectangular, Galactocentric coordinates. We showed that in many cases the numerical integration of the star motion gives significantly different results than popular rectilinear approximation.We found several new stellar candidates for close visitors in past or in future. We used a covariance matrices of the astrometric data for each star to estimate the accuracy of the obtained proximity distance and epoch. To this aim we used a Monte Carlo method, replaced each star with 10 000 of its clones and studied the distribution of their individual close passages near the Sun. We showed that for contemporary close neighbours the precision is quite good but for more distant stars it strongly depends on the quality of astrometric and kinematic data. Several examples are discussed in detail, among them the case of HIP 14473. For this star we obtained the nominal proximity distance as small as 0.22 pc 3.78 Myr ago. However there exist strong need for more precise astrometry of this star since the proximity point uncertainty is unacceptably large.

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arXiv2015

Near-parabolic comets observed in 2006-2010. II. Their past and future motion under the influence of the Galaxy field and known nearby stars

Here, we continue this research with a detailed study of their past and future motion during previous and next orbital periods under the perturbing action of our Galactic environment. At all stages of our dynamical study, we precisely propagate in time the observational uncertainties of cometary orbits. For the first time in our calculations, we fully take into account individual perturbations from all known stars or stellar systems that closely (less than 3.5 pc) approach the Sun during the cometary motion in the investigated time interval of several million years. This is done by means of a direct numerical integration of the N-body system comprising of a comet, the Sun and 90 potential stellar perturbers. We show a full review of various examples of individual stellar action on cometary motion. We conclude that perturbations from all known stars or stellar systems do not change the overall picture of the past orbit evolution of long-period comets (LPCs).The future motion of them might be seriously perturbed during the predicted close approach of Gliese 710 star but we do not observe significant energy changes. The importance of stellar perturbations is tested on the whole sample of 108 comets investigated by us so far and our previous results, obtained with only Galactic perturbations included, are fully confirmed.We present how our results can be used to discriminate between dynamically new and old near-parabolic comets and discuss the relevance of the so-called Jupiter-Saturn barrier phenomenon. Finally, we show how the Oort spike in the 1/a-distribution of near-parabolic comets is built from both dynamically new and old comets. We also point out that C/2007 W1 seems to be the first serious candidate for interstellar provenience.

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