Spitzer Dayside Emission of WASP-34b

TL;DR

This study analyzed Spitzer eclipse data of exoplanet WASP-34b using two correction techniques, refined its orbital parameters, and found its atmosphere resembles a blackbody with unique chemical hints.

Contribution

It introduces a comparative analysis of two intrapixel sensitivity correction methods and applies atmospheric retrieval to characterize WASP-34b's atmosphere.

Findings

Eclipse depths consistent within 1.1σ between models

Orbital eccentricity measured as zero

Planetary spectrum resembles a blackbody

Abstract

We analyzed two eclipse observations of the low-density transiting, likely grazing, exoplanet WASP-34b with the Spitzer Space Telescope's InfraRed Array Camera (IRAC) using two techniques to correct for intrapixel sensitivity variation: Pixel-Level Decorrelation (PLD) and BiLinearly Interpolated Subpixel Sensitivity (BLISS). When jointly fitting both light curves, timing results are consistent within 0.7$\sigma$ between the two models and eclipse depths are consistent within 1.1$\sigma$, 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 upon measurements of orbital parameters and found an eccentricity consistent with zero (0.0). Atmospheric retrieval, using our Bayesian Atmospheric Radiative Transfer code (BART), 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.