Where do long-period comets come from? 26 comets from the non-gravitational Oort spike

TL;DR

This study refines the understanding of long-period comet origins by incorporating non-gravitational forces into orbit calculations, revealing that many comets are not dynamically new and can be observed over multiple perihelion passages.

Contribution

It introduces a method to determine precise non-gravitational orbits and uses orbital evolution under Galactic tides to identify the true source regions of long-period comets.

Findings

Non-gravitational forces significantly affect orbit determinations.

Many long-period comets are not dynamically new.

Comets can be visible over multiple perihelion passages.

Abstract

The apparent source region (or regions) of long-period comets as well as the definition of the dynamically new comet are still open questions.The aim of this investigation is to look for the apparent source of selected long period comets and to refine the definition of dynamically new comets. We show that incorporation of the non-gravitational forces into the orbit determination process significantly changes the situation. We determined precise non-gravitational orbits of all investigated comets and next followed numerically their past and future motion during one orbital period. Applying ingenious Sitarski's method of creating swarms of virtual comets compatible with observations, we were able to derive the uncertainties of original and future orbital elements, as well as the uncertainties of the previous and next perihelion distances. We concluded that the past and future evolution of cometary orbits under the Galactic tide perturbations is the only way to find which comets are really dynamically new. We also have shown that a significant percentage of long-period comets can visit the zone of visibility during at least two or three consecutive perihelion passages.