Trends in Spitzer Secondary Eclipses

Wallack, Nicole L.; Knutson, Heather A.; Deming, Drake

doi:10.3847/1538-3881/abdbb2

Cited by 8 publications

(5 citation statements)

References 90 publications

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“…The flux rise is noticeable on the right panel of Figure 2 in Wallack et al (2021), and was also noted by Goyal et al (2021). The latter authors did not elaborate, but Wallack et al (2021) discussed the decreasing efficiency of heat transport for temperatures exceeding ∼1500 K, albeit they did not emphasize the abruptness of the transition in their paper. We believe that this is the same phenomenon that we measure in this paper, in spite of the modest difference in the location of the transition.…”

Section: Noticed Previouslymentioning

confidence: 85%

Emergent Spectral Fluxes of Hot Jupiters: An Abrupt Rise in Dayside Brightness Temperature Under Strong Irradiation

Deming

Line

Knutson

et al. 2023

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We study the emergent spectral fluxes of transiting hot Jupiters, using secondary eclipses from Spitzer. To achieve a large and uniform sample, we have reanalyzed all secondary eclipses for all hot Jupiters observed by Spitzer at 3.6 and/or 4.5 μm. Our sample comprises 457 eclipses of 122 planets, including eclipses of 13 planets not previously published. We use these eclipse depths to calculate the spectral fluxes emergent from the exoplanetary atmospheres, and thereby infer the temperatures and spectral properties of hot Jupiters. We find that an abrupt rise in brightness temperature, similar to a phase change, occurs on the dayside atmospheres of the population at an equilibrium temperature between 1714 and 1818 K (99% confidence limits). The amplitude of the rise is 291 ± 49 K, and two viable causes are the onset of magnetic drag that inhibits longitudinal heat redistribution, and/or the rapid dissipation of dayside clouds. We also study hot Jupiter spectral properties with respect to metallicity and temperature inversions. Models exhibiting 4.5 μm emission from temperature inversions reproduce our fluxes statistically for the hottest planets, but the transition to emission is gradual, not abrupt. The Spitzer fluxes are sensitive to metallicity for planets cooler than ∼1200 K, and most of the hot Jupiter population falls between model tracks having solar to 30× solar metallicity.

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Section: Noticed Previouslymentioning

confidence: 85%

Emergent Spectral Fluxes of Hot Jupiters: An Abrupt Rise in Dayside Brightness Temperature Under Strong Irradiation

Deming

Line

Knutson

et al. 2023

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“…Several studies have looked into trends in the ratio of 4.5-3.6 μm brightness temperatures (Kammer et al 2015;Wallack et al 2019;Garhart et al 2020;Wallack et al 2021). From our joint light-curve fits we measured brightness temperature ratios of 1.05 ± 0.14 (BLISS) and 1.13 ± 0.12 (PLD).…”

Section: Discussionmentioning

confidence: 96%

“…With the number of Jupiters with measured emission increasing, many studies have taken a statistical approach to exoplanet atmospheres, in both transmission (e.g., Baxter et al 2021) and emission (e.g., Garhart et al 2020;Wallack et al 2021). Here we compare WASP-34b against the literature of comparative exoplanetology to study how it fits into observed trends.…”

Section: Discussionmentioning

confidence: 99%

“…From our joint light-curve fits we measured brightness temperature ratios of 1.05 ± 0.14 (BLISS) and 1.13 ± 0.12 (PLD). WASP-34b may have a larger brightness temperature ratio than other planets with a similar equilibrium temperature, which generally fall below 1.0 (e.g., WASP-6b, WASP-8b, WASP-39b, TrES-1b;Wallack et al 2021), although the weak eclipses lead to large uncertainties. WASP-34b may exhibit different chemistry than other warm Jupiters at the pressures probed by these observations.…”

Section: Discussionmentioning

confidence: 99%

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Spitzer Dayside Emission of WASP-34b

Challener

Harrington²,

Cubillos³

et al. 2022

Planet. Sci. J.

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We analyzed two eclipse observations of the low-density transiting, likely grazing, exoplanet WASP-34b with the Spitzer Space Telescope’s InfraRed Array Camera using two techniques to correct for intrapixel sensitivity variation: Pixel-Level Decorrelation and BiLinearly Interpolated Subpixel Sensitivity. When jointly fitting both light curves, timing results are consistent within 0.7σ between the two models and eclipse depths are consistent within 1.1σ, where the difference is due to photometry methods, not the models themselves. By combining published radial velocity data, amateur and professional transit observations, and our eclipse timings, we improved on measurements of orbital parameters and found an eccentricity consistent with zero (0.0). Atmospheric retrieval, using our Bayesian Atmospheric Radiative Transfer code, shows that the planetary spectrum most resembles a blackbody, with no constraint on molecular abundances or vertical temperature variation. WASP-34b is redder than other warm Jupiters with a similar temperature, hinting at unique chemistry, although further observations are necessary to confirm this.

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“…Figure 9 shows the heat redistribution (ε) of KELT-9b plotted along with other hot-Jupiters. In previous papers (Wallack et al 2021;Komacek & Showman 2016), it has been shown that for hot Jupiters, the incident stellar flux is the primary decider of the level of ε. However in Bell & Cowan (2018), they predict a rising heat redistribution for UHJ due to the H 2 dissociation and recombination increasing the heat transport around the planet.…”

Section: Albedo and Heat Redistributionmentioning

confidence: 99%

The stable climate of KELT-9b

Jones

Morris

Demory

et al. 2022

A&A

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Even among the most irradiated gas giants, so-called ultra-hot Jupiters, KELT-9b stands out as the hottest planet thus far discovered with a dayside temperature of over 4500 K. At these extreme irradiation levels, we expect an increase in heat redistribution efficiency and a low Bond albedo owed to an extended atmosphere with molecular hydrogen dissociation occurring on the planetary dayside. We present new photometric observations of the KELT-9 system throughout 4 full orbits and 9 separate occultations obtained by the 30 cm space telescope CHEOPS. The CHEOPS bandpass, located at optical wavelengths, captures the peak of the thermal emission spectrum of KELT-9b. In this work we simultaneously analyse CHEOPS phase curves along with public phase curves from TESS and Spitzer to infer joint constraints on the phase curve variation, gravity-darkened transits, and occultation depth in three bandpasses, as well as derive 2D temperature maps of the atmosphere at three different depths. We find a day-night heat redistribution efficiency of ∼ 0.3 which confirms expectations of enhanced energy transfer to the planetary nightside due to dissociation and recombination of molecular hydrogen. We also calculate a Bond albedo consistent with zero. We find no evidence of variability of the brightness temperature of the planet, excluding variability greater than 1% (1σ).

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Trends in Spitzer Secondary Eclipses

Cited by 8 publications

References 90 publications

Emergent Spectral Fluxes of Hot Jupiters: An Abrupt Rise in Dayside Brightness Temperature Under Strong Irradiation

Emergent Spectral Fluxes of Hot Jupiters: An Abrupt Rise in Dayside Brightness Temperature Under Strong Irradiation

Spitzer Dayside Emission of WASP-34b

The stable climate of KELT-9b

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