Constraints on the size and dynamics of the J1407b ring system

TL;DR

This study investigates the stability of a hypothesized giant ring system around a secondary companion to star J1407, using simulations to determine conditions under which such a system could survive and cause observed eclipses.

Contribution

The paper demonstrates that a retrograde, massive companion with an eccentric orbit can sustain a large ring system consistent with observations, challenging previous assumptions about ring stability.

Findings

Prograde ring systems are strongly ruled out.

A 60-100MJup companion with an 11-year orbit can host a stable ring system.

Retrograde ring systems can survive over 10,000 orbits and produce observed eclipses.

Abstract

Context. J1407 (1SWASP J140747.93-394542.6 in full) is a young star in the Scorpius-Centaurus OB association that underwent a series of complex eclipses over 56 days in 2007. To explain these, it was hypothesised that a secondary substellar companion, J1407b, has a giant ring system filling a large fraction of the Hill sphere, causing the eclipses. Observations have not successfully detected J1407b, but do rule out circular orbits for the companion around the primary star. Aims. We test to what degree the ring model of J1407b could survive in an eccentric orbit required to fit the observations. Methods. We run N-body simulations under the AMUSE framework to test the stability of Hill radius-filling systems where the companion is on an eccentric orbit. Results. We strongly rule out prograde ring systems and find that a secondary of 60 to 100MJup with an 11 year orbital period and retrograde orbiting material can survive for at least $10^4$ orbits and produce eclipses with similar durations as the observed one.