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

TL;DR

This work updates the CODE catalogue to deliver a dynamically homogeneous, large-sample orbital database for long-period comets, emphasizing near-parabolic objects. It employs full Monte Carlo swarms and comprehensive perturbations from planets, the Galactic tide, and passing stars to propagate orbits to previous and next perihelia and to quantify uncertainties. Key outcomes include 983 orbital solutions for 369 comets and enhanced coverage for high-$a$ LPCs, alongside analyses of original $1/a$ distributions and dynamical status via $q_{ m prev}$, with two models for orbit evolution (with/without stellar perturbations) and PB vs preferred solutions. The authors argue that robust dynamical classifications require considering $q_{ m prev}$, particularly when stellar perturbations are significant, making CODE a vital resource for studying LPC origins and Oort Cloud structure; data availability is ensured to support ongoing updates and reproducibility.

Abstract

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.

Figures (5)

• Figure 1: Distribution $1/a_{\rm ori}$ vs original perihelion distance for the sample of all LPCs in the CODE catalogue, excluding 17 LPCs with hyperbolic original orbits; Shown are parameters for orbital solutions marked as preferred for studies of the past motion. Median values of $1/a_{\rm ori}$ and $q_{\rm ori}$ are shown using dotted red lines.
• Figure 2: Distributions $1/a_{\rm ori}$ for two samples of LPCs: small perihelion comets (green line histogram in the upper panels) and large perihelion comets (full blue histogram in the upper panels) and the sum of all LPCs included in the CODE catalogue (full red histogram in the lower panels); swarms of 5001 VCs were used, bin width: 10 au$_{-6}$. Left side panels show statistics using the 'preferred' orbits while the right side panels -- statistics based on PB solutions (i.e. orbits preferred for backward orbital evolution).
• Figure 3: Previous perihelion distance dependence on an original semi-major axis reciprocal, only fully returning to previous perihelion 222
• Figure 4: Values of $1/a_{\rm ori}$ for all solutions provided in the CODE catalogue for LPCs listed in Table \ref{['tab:Oortspikecomets10au']}, excluding those based solely on the post-perihelion part of orbits. The vertical axis represents the ordinal number of comet when sorted by $q$. The same number is in the final column of Table \ref{['tab:Oortspikecomets10au']}. The preferred solutions with their uncertainties are shown in red, the PB solutions are marked by yellow points, and all remaining values are plotted in black. The green dashed vertical line indicates the same reference value as in Fig. \ref{['fig:q_prev_versus_a_ori']}.
• Figure 5: Sample of 48 LPCs from the CODE catalogue having $q>7$ au. The upper and lowest [panels shows original and future distribution of 1/a, respectively while the middle panel gives the distribution of planetary perturbations during the passage through the planetary system. The light grey vertical band indicates the region occupied by Oort spike comets. The range of the horizontal axes is chosen to include the tails of the $a_{\rm ori}$ distribution.