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, Erin M.; Stevenson, Kevin B.; Bean, Jacob L.; Bell, Taylor; Cowan, Nicolas B.; Dang, Lisa; Désert, Jean-Michel; Fortney, Jonathan J.; Keating, Dylan; Kempton, Eliza M.-R.; Komacek, Thaddeus D.; Lewis, Nikole K.; Mansfield, Megan; Morley, Caroline; Parmentier, Vivien; Rauscher, Emily; Swain, Mark R.; Zellem, Robert T.; Showman, Adam P.

doi:10.3847/1538-3881/ac6261

“…Extracting exoplanets signals at the level of 100 parts per million (ppm) can be therefore extremely challenging and requires the removal of significant instrumental effects (for a review, see Ingalls et al 2016). Over the past decade, improvements in observing strategy and development of a suite of techniques to remove IRAC time-correlated noise have yielded robust thermal phase curves for many short-period exoplanets (May et al 2022). However, in addition to the challenges of observing small planets, the 55 Cnc e Spitzer data are particularly complicated to analyze:…”

Section: Introductionmentioning

confidence: 99%

Revisiting the Iconic Spitzer Phase Curve of 55 Cancri e: Hotter Dayside, Cooler Nightside, and Smaller Phase Offset

Mercier

¹

,

Dang

²

,

Cowan

³

et al. 2022

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Thermal phase curves of short-period exoplanets provide the best constraints on the atmospheric dynamics and heat transport in their atmospheres. The published Spitzer Space Telescope phase curve of 55 Cancri e, an ultra-short-period super-Earth, exhibits a large phase offset suggesting significant eastward heat recirculation, unexpected on such a hot planet. We present our rereduction and analysis of these iconic observations using the open source and modular Spitzer Phase Curve Analysis pipeline. In particular, we attempt to reproduce the published analysis using the same instrument detrending scheme as the original authors. We retrieve the dayside temperature ( T day = 3771 − 520 + 669 K), nightside temperature ( T night < 1649 K at 2σ), and longitudinal offset of the planet's hot spot, and quantify how they depend on the reduction and detrending. Our reanalysis suggests that 55 Cancri e has a negligible hot spot offset of − 12 − 18 + 21 degrees east. The small phase offset and cool nightside are consistent with the poor heat transport expected on ultra-short-period planets. The high dayside 4.5 μm brightness temperature is qualitatively consistent with SiO emission from an inverted rock vapor atmosphere.

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“…Therefore, repeated MIRI LRS observations would likely not be able to place an improved upper limit on the thickness variations. May & Stevenson 2020;May et al 2022). This systematic error is likely the source of the discrepancy between our individual and semi-shared fits of the 2014 data, and those of the 2019 data.…”

Section: Reanalyses Of Wasp-43b's 45 Micron Phase Curvementioning

confidence: 80%

“…To date, there have been no published observing programs designed to search for phase curve variability at medium infrared wavelengths, such as those probed by Spitzer/IRAC. Repeated phase curve observations have been taken using Spitzer to help correct the strong systematics that are often present in 3.6 μm data (e.g., WASP-12b (Bell et al 2019), WASP-76b (May et al 2021), and WASP-52b (May et al 2022)) and to measure low-amplitude phase curve signals (e.g., K2-141b (Zieba et al 2022)), but it is difficult to probe variability with these data sets. Repeat phase curve observations at medium infrared wavelengths present a bridge between existing constraints on variability, and a new test on the variable nature of hot Jupiter atmospheres.…”

Section: Introductionmentioning

confidence: 99%

A Lack of Variability between Repeated Spitzer Phase Curves of WASP-43b

Murphy

¹

,

Beatty

²

,

Roman

³

et al. 2023

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Though the global atmospheres of hot Jupiters have been extensively studied using phase curve observations, the level of time variability in these data is not well constrained. To investigate possible time variability in a planetary phase curve, we observed two full-orbit phase curves of the hot Jupiter WASP-43b at 4.5 μm using the Spitzer Space Telescope, and reanalyzed a previous 4.5 μm phase curve from Stevenson et al. We find no significant time variability between these three phase curves, which span timescales of weeks to years. The three observations are best fit by a single phase curve with an eclipse depth of 3907 ± 85 ppm, a dayside-integrated brightness temperature of 1479 ± 13 K, a nightside integrated brightness temperature of 755 ± 46 K, and an eastward-shifted peak of 10.°4 ± 1.°8. To model our observations, we performed 3D general circulation model simulations of WASP-43b with simple cloud models of various vertical extents. In comparing these simulations to our observations, we find that WASP-43b likely has a cloudy nightside that transitions to a relatively cloud-free dayside. We estimate that any change in WASP-43b’s vertical cloud thickness of more than three pressure scale heights is inconsistent with our observed upper limit on variation. These observations, therefore, indicate that WASP-43b’s clouds are stable in their vertical and spatial extent over timescales up to several years. These results strongly suggest that atmospheric properties derived from previous, single Spitzer phase curve observations of hot Jupiters likely show us the equilibrium properties of these atmospheres.

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“…Longitudinal heat circulations for individual hot Jupiters are best studied using thermal infrared phase curves, the studies of which have been extensive (e.g., Knutson et al 2007Knutson et al , 2012Wong et al 2015;Stevenson et al 2017;Kreidberg et al 2018;Bell et al 2021;Dang et al 2022;May et al 2022). Phase curves can delineate emergent flux over the full range of planetary longitude, whereas eclipses yield only the dayside flux.…”

Section: Emergent Fluxes and Dayside Temperaturementioning

confidence: 99%

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

Deming

¹

,

Line

²

,

Knutson

³

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

Cited by 16 publications

References 94 publications

Revisiting the Iconic Spitzer Phase Curve of 55 Cancri e: Hotter Dayside, Cooler Nightside, and Smaller Phase Offset

Revisiting the Iconic Spitzer Phase Curve of 55 Cancri e: Hotter Dayside, Cooler Nightside, and Smaller Phase Offset

A Lack of Variability between Repeated Spitzer Phase Curves of WASP-43b

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

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