Exploring the Effects of Active Magnetic Drag in a General Circulation Model of the Ultrahot Jupiter WASP-76b

Beltz, Hayley; Rauscher, Emily; Roman, Michael T.; Guilliat, Abigail

doi:10.3847/1538-3881/ac3746

Cited by 51 publications

(96 citation statements)

References 70 publications

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“…This would be most apparent in the upper atmosphere, where the ionisation fractions can be extremely high (Lee et al 2020). Beltz et al (2022) show that even small magnetic drag can have a large effect on the atmospheric dynamical properties of HJ atmospheres, suggesting that similar behaviour to that seen in Beltz et al ( 2022) is probably occurring in our WD-BD cases. Clouds may also provide an important effect in setting the nightside and dayside fluxes of the BDs.…”

Section: Discussionsupporting

confidence: 80%

Sunbathing under white light -- 3D modelling of brown dwarf - white dwarf atmospheres with strong UV irradiation

Lee¹,

Lothringer²,

Casewell³

et al. 2022

Preprint

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The atmospheres of brown dwarfs orbiting in close proximity to their parent white dwarf represent some of the most extreme irradiated environments known. Understanding their complex dynamical mechanisms pushes the limits of theoretical and modelling efforts, making them valuable objets to study to test contemporary understanding of irradiated atmospheres. We use the Exo-FMS GCM to simulate the brown dwarfs WD0137-349B, SDSS J141126.20+200911.1B and EPIC212235321B, first coupled to a multi-banded grey radiativetransfer scheme then a spectral correlated-k scheme with high temperature opacity tables. We then post-process the GCM results using gCMCRT to compare to available observational data. Our GCM models predict strongly temperature inverted atmospheres, spanning many decades in pressure due to impact of UV band heating. Post-processing of our models suggest that the day-night contrast is too small in the GCM results. We therefore suggest that the formation of cloud particles as well as atmospheric drag effects such as magnetic drag are important considerations in setting the day-night temperature contrast for these objects.

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Section: Discussionsupporting

confidence: 80%

Sunbathing under white light -- 3D modelling of brown dwarf - white dwarf atmospheres with strong UV irradiation

Lee¹,

Lothringer²,

Casewell³

et al. 2022

Preprint

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“…There are several lines of evidence indicating that the magnetic fields of hot Jupiters may be relatively strong (10-100 G), including the inflated radii of these planets (Batygin & Stevenson 2010;Yadav & Thorngren 2017) and evidence for magnetic star-planet interactions in a few systems (SPI; Cauley et al 2019). Other observations suggest that these planets may have more modest field strengths (1-10 G), including ultraviolet observations of Lyman-α and ionized carbon lines in HAT-P-11b (Ben-Jaffel et al 2022), and a small inferred hotspot offset in the phase curve of WASP-76b which might be caused by Lorentz drag (May et al 2021;Beltz et al 2022). Elsasser number scalings also predict more moderate magnetic field strengths (Stevenson 2003).…”

Section: Low Mass-loss Rates For Wasp-80b and Wasp-52bmentioning

confidence: 97%

The Upper Edge of the Neptune Desert Is Stable Against Photoevaporation

Vissapragada¹,

Knutson²,

Greklek-McKeon³

et al. 2022

Preprint

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Transit surveys indicate that there is a deficit of Neptune-sized planets on close-in orbits. If this "Neptune desert" is entirely cleared out by atmospheric mass loss, then planets at its upper edge should only be marginally stable against photoevaporation, exhibiting strong outflow signatures in tracers like the metastable helium triplet. We test this hypothesis by carrying out a 12-night photometric survey of the metastable helium feature with Palomar/WIRC, targeting seven gas-giant planets orbiting K-type host stars. Eight nights of data are analyzed here for the first time along with reanalyses of four previously-published datasets. We strongly detect helium absorption signals for WASP-69b, HAT-P-18b, and HAT-P-26b; tentatively detect signals for WASP-52b and NGTS-5b; and do not detect signals for WASP-177b and WASP-80b. We interpret these measured excess absorption signals using grids of isothermal Parker wind models to derive mass-loss rates, which are typically around 10 10 − 10 11 g s −1 . Our empirically constrained mass-loss rates are in good agreement with predictions from the 1D hydrodynamical outflow code ATES for all planets except WASP-52b and WASP-80b, where our data suggest that the outflows are much smaller than predicted. Excluding these two planets, the outflows for the rest of the sample are consistent with a mean energy-limited outflow efficiency of ε = 0.41 +0.16 −0.13 . Even when we make the relatively conservative assumption that gas-giant planets experience energy-limited outflows at this efficiency for their entire lives, photoevaporation would still be too inefficient to carve the upper boundary of the Neptune desert. We conclude that this feature of the exoplanet population is a pristine tracer of giant planet formation and migration mechanisms.

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“…Figure 12 shows the 4.5 μm data compared to three-dimensional model predictions from Roman et al (2021) for both cloudy and clear cases at two different planetary gravities. While these models do use radiatively active clouds, which are important at cooler temperatures, we note that these do not consider magnetic drag (see, e.g., Rauscher & Menou 2013;Rogers & Komacek 2014;Rogers & Showman 2014;Beltz et al 2022), which is likely to be important at high temperatures, nor H 2 dissociation or nongray impacts, all of which impact the hotspot offset and circulation (for the impact of the choice of radiative scheme on predicted phase curves, see, e.g., Lee et al 2021). Nonequilibrium chemistry can also impact the emergent phase curve and is not considered in the model predictions we consider here (e.g., Steinrueck et al 2019).…”

Section: Population Trendsmentioning

confidence: 99%

A New Analysis of Eight Spitzer Phase Curves and Hot Jupiter Population Trends: Qatar-1b, Qatar-2b, WASP-52b, WASP-34b, and WASP-140b

May

Stevenson

Bean

et al. 2022

Self Cite

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With over 30 phase curves observed during the warm Spitzer mission, the complete data set provides a wealth of information relating to trends and three-dimensional properties of hot Jupiter atmospheres. In this work we present a comparative study of seven new Spitzer phase curves for four planets with equilibrium temperatures T eq ∼ 1300K: Qatar-2b, WASP-52b, WASP-34b, and WASP-140b, as well as a reanalysis of the 4.5 μm Qatar-1b phase curve due to the similar equilibrium temperature. In total, five 4.5 μm phase curves and three 3.6 μm phase curves are analyzed here with a uniform approach. Using these new results, in combination with literature values for the entire population of published Spitzer phase curves of hot Jupiters, we present evidence for a linear trend of increasing hotspot offset with increasing orbital period, as well as observational evidence for two classes of planets in apparent redistribution versus equilibrium temperature parameter space, and tentative evidence for a dependence of hotspot offset on planetary surface gravity in our ∼1300 K sample. We do not find trends in apparent heat redistribution with orbital period or gravity. Nonuniformity in literature Spitzer data analysis techniques precludes a definitive determination of the sources or lack of trends.

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Exploring the Effects of Active Magnetic Drag in a General Circulation Model of the Ultrahot Jupiter WASP-76b

Cited by 51 publications

References 70 publications

Sunbathing under white light -- 3D modelling of brown dwarf - white dwarf atmospheres with strong UV irradiation

Sunbathing under white light -- 3D modelling of brown dwarf - white dwarf atmospheres with strong UV irradiation

The Upper Edge of the Neptune Desert Is Stable Against Photoevaporation

A New Analysis of Eight Spitzer Phase Curves and Hot Jupiter Population Trends: Qatar-1b, Qatar-2b, WASP-52b, WASP-34b, and WASP-140b

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