Editing Ring system (section)

== Rings around exoplanets ==
[[File:Ring formation around extrasolar planet.webm|thumb|Ring formation around extrasolar planet]]
Because all [[giant planet]]s of the Solar System have rings, the existence of [[exoplanet]]s with rings is plausible. Although particles of [[ice]], the material that is predominant in the [[rings of Saturn]], can only exist around planets beyond the [[Frost line (astrophysics)|frost line]], within this line rings consisting of rocky material can be stable in the long term.<ref name="schlichting2011"/> Such ring systems can be detected for planets observed by the [[transit method]] by additional reduction of the light of the central star if their opacity is sufficient. As of 2024, two candidate extrasolar ring systems have been found by this method, around [[HIP 41378 f]]<ref name="akinsanmi2020"/> and [[K2-33b]].<ref name="Ohno2022"/>

[[Fomalhaut b]] was found to be large and unclearly defined when detected in 2008. This was hypothesized to either be due to a cloud of dust attracted from the dust disc of the star, or a possible ring system,<ref name="kalas2008"/> though in 2020 Fomalhaut b itself was determined to very likely be an expanding debris cloud from a collision of asteroids rather than a planet.<ref name="PNAS-20200420"/> Similarly, [[Proxima Centauri c]] has been observed to be far brighter than expected for its low mass of 7 Earth masses, which may be attributed to a ring system of about 5 {{Jupiter radius|link=y}}.<ref name="Gratton2020"/>

A 56-day-long sequence of dimming events in the star [[V1400 Centauri]] observed in 2007 was interpreted as a [[substellar object]] with a [[circumstellar disk]] or massive rings transiting the star.<ref name="Kenworthy2015"/> This substellar object, dubbed "[[J1407b]]", is most likely a free-floating [[brown dwarf]] or [[rogue planet]] several times the mass of Jupiter.<ref name="Kenworthy2020"/> The circumstellar disk or ring system of J1407b is about {{convert|0.6|AU|km mi|abbr=out|lk=in}} in radius.<ref name="Kenworthy2015"/> J1407b's transit of V1400 Centauri revealed gaps and density variations within its disk or ring system, which has been interpreted as hints of exomoons or exoplanets forming around J1407b.<ref name="Kenworthy2015"/>