Constraints on the size and dynamics of the J1407b ring system

Rieder, Steven; Kenworthy, Matthew A.

doi:10.1051/0004-6361/201629567

Cited by 19 publications

(31 citation statements)

References 25 publications

(33 reference statements)

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“…Thus we could assume they are gravita-tionally bound within the Hill spheres of planetesimals or planet-sized objects, where the Hill sphere is defined as R Hill = ξa 3 M p /(3M ) and ξ is the fraction out to which orbits are stable. Figure 9 shows the Hill spheres of objects of various diameters, assuming bulk densities of 3 g cm −3 and using ξ = 0.5 (i.e., an average between that expected from retrograde and prograde orbits; Rieder & Kenworthy 2016). Given these constraints, the Hill spheres of objects with diameters D ∼ 250-25,000 km (i.e., spanning large-asteroid to super-Earth sizes) can produce the observed dips.…”

Section: Gravitationally-bound Planetesimal Clouds?mentioning

confidence: 98%

The little dippers: transits of star-grazing exocomets?

Ansdell

Gaidos

Jacobs

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We describe EPIC 205718330 and EPIC 235240266, two systems identified in the K2 data whose light curves contain episodic drops in brightness with shapes and durations similar to those of the young "dipper" stars, yet shallower by ∼1-2 orders of magnitude. These "little dippers" have diverse profile shapes with durations of 0.5-1.0 days and depths of 0.1-1.0% in flux; however, unlike most of the young dipper stars, these do not exhibit any detectable infrared excess indicative of protoplanetary disks, and our ground-based follow-up spectra lack any signatures of youth while indicating these objects as kinematically old. After ruling out instrumental and/or data processing artifacts as sources of the dimming events, we investigate possible astrophysical mechanisms based on the light curve and stellar properties. We argue that the little dippers are consistent with transits of star-grazing exocomets, and speculate that they are signposts of massive non-transiting exoplanets driving the close-approach orbits.

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Section: Gravitationally-bound Planetesimal Clouds?mentioning

confidence: 98%

The little dippers: transits of star-grazing exocomets?

Ansdell

Gaidos

Jacobs

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…The difficulty is that such signals are subtle and difficult to discern in current data. In a few cases, potential rings or constraints on rings have been made in this way (Heising et al 2015;Aizawa et al 2017Aizawa et al , 2018, and in at least one instance it has been argued that an exoplanet has a giant ring system from a series of complex eclipses (Kenworthy & Mamajek 2015;Rieder & Kenworthy 2016). There is clearly still a lot we do not know about the rings of exoplanets.…”

Section: Introductionmentioning

confidence: 99%

Exploring Whether Super-puffs can be Explained as Ringed Exoplanets

Piro

Vissapragada

2020

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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.

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“…2. We do not consider the highly eccentric orbit of J1407b about the primary which is thought to take the ring system close enough at pericentre that the Hill radius reduces below the measured radial extent of the ring system (Rieder & Kenworthy 2016 3. If J1407b is bound to the primary on a highly elliptical orbit then moons external to the ring system (> 0.6 ), which are required for MMR's, will exist outside the Hill radius during pericentre.…”

Section: Discussionmentioning

confidence: 99%

“…A highly eccentric orbit would also result in outer parts of the ring system being located outside the Hill radius when J1407b is at pericentre (Rieder & Kenworthy 2016). A collision between two large rocky objects within the Hill sphere of J1407b could also explain the favoured retrograde orbit of the ring reported by Rieder & Kenworthy (2016).…”

Section: Introductionmentioning

confidence: 97%

Mean motion resonances with nearby moons: an unlikely origin for the gaps observed in the ring around the exoplanet J1407b

Sutton

2019

Monthly Notices of the Royal Astronomical Society

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With the use of numerical models, we investigate whether Mean Motion Resonances (MMR) with nearby moons to the J1407b ring system were the cause of the observed 0.0267 wide gap located at 0.4 . Only one location of a moon at 0.63 (corresponding to a 2:1 MMR) was found to form a gap at 0.4 over short time periods of < 100 . However, the proximity of a low mass moon (0.08 ⊕ ) caused significant scattering of the outer ring edge at 0.6 , along with the formation of an additional gap at the 3:2 MMR (0.485 ), which is not consistent with observations. Further models with moons located at MMR's 3:1, 4:1, 7:3 and 5:3 failed to form gaps at 0.4 for time periods < 100 . Instead, gaps were formed in the ring at 3:2 and 2:1 MMR's which resulted in gaps at radial locations between 0.44 − 0.56 . Additionally, gaps also take longer than one orbital period of J1407b about the primary to form. Given that J1407b is on a highly eccentric orbit and is thought to strongly perturb the ring at apocentre it appears unlikely that gaps form due to MMR's with nearby moons as opposed to embedded moons. Including an appropriate total mass of the ring equal to Earth a dampening effect was witnessed on the gap formation process, causing an increase in the time required to open a gap due to MMR's. Therefore, we conclude the observed gap at 0.4 is unlikely to be caused by MMR's with nearby moons.

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Constraints on the size and dynamics of the J1407b ring system

Cited by 19 publications

References 25 publications

The little dippers: transits of star-grazing exocomets?

The little dippers: transits of star-grazing exocomets?

Exploring Whether Super-puffs can be Explained as Ringed Exoplanets

Mean motion resonances with nearby moons: an unlikely origin for the gaps observed in the ring around the exoplanet J1407b

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