Examining the broadband emission spectrum of WASP-19b: A new z band eclipse detection

TL;DR

This study measures the z band eclipse of WASP-19b and combines it with previous data to analyze its atmospheric composition, finding evidence for super-solar carbon levels and constraining haze particle sizes.

Contribution

It provides new z band eclipse measurements and uses radiative transfer modeling to explore atmospheric compositions, including C/O ratios and haze effects, of WASP-19b.

Findings

Models with super-solar carbon best fit the data

Haze particles smaller than 0.5 micron are unlikely in WASP-19b

The z band eclipse measurement is consistent with previous observations

Abstract

WASP-19b is one of the most irradiated hot-Jupiters known. Its secondary eclipse is the deepest of all transiting planets, and has been measured in multiple optical and infrared bands. We obtained a z band eclipse observation, with measured depth of 0.080 +/- 0.029 %, using the 2m Faulkes Telescope South, that is consistent with the results of previous observations. We combine our measurement of the z band eclipse with previous observations to explore atmosphere models of WASP-19b that are consistent with the its broadband spectrum. We use the VSTAR radiative transfer code to examine the effect of varying pressure-temperature profiles and C/O abundance ratios on the emission spectrum of the planet. We find models with super-solar carbon enrichment best match the observations, consistent with previous model retrieval studies. We also include upper atmosphere haze as another dimension in the interpretation of exoplanet emission spectra, and find that particles <0.5 micron in size are unlikely to be present in WASP-19b.