No Evidence for Lunar Transit in New Analysis of Hubble Space Telescope Observations of the Kepler-1625 System

Kreidberg, Laura; Luger, Rodrigo; Bedell, Megan

doi:10.3847/2041-8213/ab20c8

Cited by 72 publications

(62 citation statements)

References 33 publications

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“…Such searches for low-amplitude photometric signals can be compromised by time-correlated systematics, whether instrumental (e.g., Kepler's sudden pixel sensitivity dropout) or astrophysical (e.g., stellar variability) in nature (Jenkins et al 2010;Christiansen et al 2013;Kipping et al 2012Kipping et al , 2015. Additionally, different detrending methodologies seem to deviate at the required 100 ppm level even for HST measurements of Kepler 1625, a star with similar brightness to the super-puffs studied here (Teachey & Kipping 2018;Kreidberg et al 2019;Teachey et al 2019;Heller et al 2019).…”

Section: Piro and Vissapragadamentioning

confidence: 80%

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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Section: Piro and Vissapragadamentioning

confidence: 80%

Exploring Whether Super-puffs can be Explained as Ringed Exoplanets

Piro

Vissapragada

2020

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“…After TK18, the first E-mail: mario.sucerquia@uv.cl to investigate the combined Kepler and Hubble data into one dataset were Heller, Rodenbeck & Bruno (2019), who came up with alternative explanations for the exomoon interpretation. Also, by analysing the single Hubble transit in TK18, Kreidberg, Luger & Bedell (2019) have reported that the exomoon signal was not found. But if upcoming studies confirm it, this would be a remarkable discovery like that of the first exoplanet more than 20 years ago: 51 Pegasi b (Mayor & Queloz 1995).…”

Section: Introductionmentioning

confidence: 99%

Can close-in giant exoplanets preserve detectable moons?

Sucerquia

Ramírez

Alvarado-Montes

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Exoplanet discoveries have motivated numerous efforts to find unseen populations of exomoons, yet they have been unsuccessful. A plausible explanation is that most discovered planets are located on close-in orbits, which would make their moons prone to tidal evolution and orbital detachment. In recent models of tidally-driven migration of exomoons, evolving planets might prevent what was considered their most plausible fate (i.e. colliding against their host planet), favouring scenarios where moons are pushed away and reach what we define as the satellite tidal orbital parking distance (a stop ), which is often within the critical limit for unstable orbits and depends mainly on the system's initial conditions: mass-ratio, semi-major axes, and rotational rates. By using semi-analytical calculations and numerical simulations, we calculate a stop for different initial system parameters and constrain the transit detectability of exomoons around close-in planets. We found that systems with M m /M p ≥ 10 −4 , which are less likely to form, are also stable and detectable with present facilities (e.g. Kepler and TESS ) through their direct and secondary effects in planet+moon transit, as they are massive, oversized, and migrate slowly. In contrast, systems with lower moon-to-planet mass ratios are ephemeral and hardly detectable. Moreover, any detection, confirmation, and full characterisation would require both the short cadence capabilities of TESS and high photometric sensitivity of ground-based observatories. Finally, despite the shortage of discovered long-period planets in currently available databases, the tidal migration model adopted in this work supports the idea that they are more likely to host the first detectable exomoon.

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“…6. CONCLUSIONS Given that the prospect of discovering extrasolar satellites with masses M 10 −2 M ⊕ by radial velocity, or radii R 3 × 10 −1 R ⊕ by transit techniques are bleak at present (Teachey & Kipping (2018); Kreidberg et al (2019)), we described in this work how gas signatures of Na I & K I at a hot Jupiter could be indicating the presence of a geologicallyactive satellite subject to the ambient plasma. This appears to be the case for at least one such system, WASP 49-b.…”

Section: An Exo-io At Wasp 49-b ?mentioning

confidence: 82%

“…It was shown that if the tidal Q for the planet, Q p is of the order of the equilibrium tide limit, Q p ∼ 10 12 as first derived by Goldreich & Nicholson (1977) and improved by Wu (2005a), even Earth-mass exomoons around hot Jupiters could be tidally-stable on ∼ Gyr timescales. Kepler data has not yet detected such exomoons, except for the recent tentative identification of a Uranus-sized candidate Kepler 1625-b at ∼ 1 AU (Teachey & Kipping (2018); Kreidberg et al (2019)). The observation of a close-in exomoon would in principle be able to constrain the low tidal Q values used in the literature (Barnes & O'Brien (2002); Weidner & Horne (2010)) previously set to Jupiter's ∼ 10 5 (Lainey & Tobie (2005)).…”

Section: Tidal Stability Of An Exo-iomentioning

confidence: 99%

Sodium and Potassium Signatures of Volcanic Satellites Orbiting Close-in Gas Giant Exoplanets

Oza

Johnson

Lellouch

et al. 2019

ApJ

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Extrasolar satellites are generally too small to be detected by nominal searches. By analogy to the most active body in the Solar System, Io, we describe how sodium (Na I) and potassium (K I) gas could be a signature of the geological activity venting from an otherwise hidden exo-Io. Analyzing ∼ a dozen close-in gas giants hosting robust alkaline detections, we show that an Io-sized satellite can be stable against orbital decay below a planetary tidal Q p 10 11 . This tidal energy is focused into the satellite driving a ∼ 10 5±2 higher mass loss rate than Io's supply to Jupiter's Na exosphere, based on simple atmospheric loss estimates. The remarkable consequence is that several exo-Io column densities are on average more than sufficient to provide the ∼ 10 10±1 Na cm −2 required by the equivalent width of exoplanet transmission spectra. Furthermore, the benchmark observations of both Jupiter's extended (∼ 1000 R J ) Na exosphere and Jupiter's atmosphere in transmission spectroscopy yield similar Na column densities that are purely exogenic in nature. As a proof of concept, we fit the "high-altitude" Na at WASP 49-b with an ionization-limited cloud similar to the observed Na profile about Io. Moving forward, we strongly encourage time-dependent ingress and egress monitoring along with spectroscopic searches for other volcanic volatiles.

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No Evidence for Lunar Transit in New Analysis of Hubble Space Telescope Observations of the Kepler-1625 System

Cited by 72 publications

References 33 publications

Exploring Whether Super-puffs can be Explained as Ringed Exoplanets

Exploring Whether Super-puffs can be Explained as Ringed Exoplanets

Can close-in giant exoplanets preserve detectable moons?

Sodium and Potassium Signatures of Volcanic Satellites Orbiting Close-in Gas Giant Exoplanets

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