2011/04/19 by Hilke E. Schlichting, Philip Chang · 4 citations
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.1088/0004-637x/734/2/117
Accepted for publication in ApJ
arxiv created 2011/04/19 · openalex publication_date 2011/06/06 · arxiv updated 2015/05/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We discuss the nature of rings that may exist around extrasolar planets. Taking the general properties of rings around the gas giants in the solar system, we infer the likely properties of rings around exoplanets that reside inside the ice line. Due to their proximity to their host star, rings around such exoplanets must primarily consist of rocky materials. However, we find that despite the higher densities of rock compared to ice, most of the observed extrasolar planets with reliable radius measurements have sufficiently large Roche radii to support rings. For the currently known transiting extrasolar planets, Poynting–Robertson drag is not effective in significantly altering the dynamics of individual ring particles over a time span of 10 8 yr provided that they exceed about 1 m in size. In addition, we show that significantly smaller ring particles can exist in optically thick rings, for which we find typical ring lifetimes ranging from a few times 10 6 to a few times 10 9 yr. Most interestingly, we find that many of the rings could have nontrivial Laplacian planes due to the increased effects of the orbital quadrupole caused by the exoplanets' proximity to their host star, allowing a constraint on the J 2 of extrasolar planets from ring observations. This is particularly exciting, since a planet's J 2 reveals information about its interior structure. Furthermore, measurements of an exoplanet's J 2 from warped rings and of its oblateness would together place limits on its spin period. Based on the constraints that we have derived for extrasolar rings, we anticipate that the best candidates for ring detections will come from transit observations by the Kepler spacecraft of extrasolar planets with semimajor axes ∼0.1 AU and larger.