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Exploring Whether Super-puffs can be Explained as Ringed Exoplanets

Piro, Anthony L. and Vissapragada, Shreyas (2020) Exploring Whether Super-puffs can be Explained as Ringed Exoplanets. Astronomical Journal, 159 (4). Art. No. 131. ISSN 1538-3881. doi:10.3847/1538-3881/ab7192.

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An intriguing, growing class of planets are the "super-puffs," objects with exceptionally large radii for their masses and thus correspondingly low densities (≾0.3 g cm⁻³). Here we consider whether they could have large inferred radii because they are in fact ringed. This would naturally explain why super-puffs have thus far only shown featureless transit spectra. We find that this hypothesis can work in some cases but not all. The close proximity of the super-puffs to their parent stars necessitates rings with a rocky rather than icy composition. This limits the radius of the rings, and makes it challenging to explain the large size of Kepler 51b, 51c, 51d, and 79d unless the rings are composed of porous material. Furthermore, the short tidal locking timescales for Kepler 18d, 223d, and 223e mean that these planets may be spinning too slowly, resulting in a small oblateness and rings that are warped by their parent star. Kepler 87c and 177c have the best chance of being explained by rings. Using transit simulations, we show that testing this hypothesis requires photometry with a precision of somewhere between ~10 ppm and ~50 ppm, which roughly scales with the ratio of the planet and star's radii. We conclude with a note about the recently discovered super-puff HIP 41378f.

Item Type:Article
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URLURL TypeDescription Paper
Piro, Anthony L.0000-0001-6806-0673
Vissapragada, Shreyas0000-0003-2527-1475
Additional Information:© 2020 The American Astronomical Society. Received 2019 November 26; revised 2020 January 28; accepted 2020 January 28; published 2020 February 28. We thank Babatunde Akinsanmi, Jason Barnes, Konstantin Batygin, Eve Lee, Heather Knutson, Jessica Libby-Roberts, Alex Teachey, and Johanna Teske for helpful discussions. S.V. is supported by an NSF Graduate Research Fellowship and the Paul & Daisy Soros Fellowship for New Americans.
Funding AgencyGrant Number
NSF Graduate Research FellowshipUNSPECIFIED
Paul and Daisy Soros FellowshipUNSPECIFIED
Subject Keywords:Occultation; Exoplanets; Exoplanet rings; Exoplanet detection methods
Issue or Number:4
Classification Code:Unified Astronomy Thesaurus concepts: Occultation (1148); Exoplanets (498); Exoplanet rings (494); Exoplanet detection methods (489)
Record Number:CaltechAUTHORS:20200302-135029430
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Official Citation:Anthony L. Piro and Shreyas Vissapragada 2020 AJ 159 131
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101656
Deposited By: Tony Diaz
Deposited On:02 Mar 2020 22:24
Last Modified:16 Nov 2021 18:04

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