Modeling giant extrasolar ring systems in eclipse and the case of J1407b: sculpting by exomoons?

TL;DR

This paper models a giant ring system around an unseen exoplanet, J1407b, explaining complex eclipse data and suggesting the presence of exomoons shaping the rings, marking one of the first such observations outside our Solar System.

Contribution

It presents a detailed azimuthally symmetric ring model fitting the eclipse light curve, revealing a large, structured ring system with gaps likely caused by exomoons.

Findings

Ring system extends to 0.6 AU with 37 rings.

A gap at 0.4 AU suggests exomoon activity.

Ring mass estimated at about 100 Moon masses.

Abstract

The light curve of 1SWASP J140747.93-394542.6, a $\sim$16 Myr old star in the Sco-Cen OB association, underwent a complex series of deep eclipses that lasted 56 days, centered on April 2007. This light curve is interpreted as the transit of a giant ring system that is filling up a fraction of the Hill sphere of an unseen secondary companion, J1407b. We fit the light curve with a model of an azimuthally symmetric ring system, including spatial scales down to the temporal limit set by the star's diameter and relative velocity. The best ring model has 37 rings and extends out to a radius of 0.6 AU (90 million km), and the rings have an estimated total mass on the order of $100 M_{Moon}$. The ring system has one clearly defined gap at 0.4 AU (61 million km), which we hypothesize is being cleared out by a $< 0.8 M_{\oplus}$ exosatellite orbiting around J1407b. This eclipse and model implies that we are seeing a circumplanetary disk undergoing a dynamic transition to an exosatellite-sculpted ring structure and is one of the first seen outside our Solar system.