ACCESS: Ground-based Optical Transmission Spectroscopy of the Hot Jupiter WASP-4b
Rackham, Benjamin V.
AffiliationUniv Arizona, Steward Observ, Dept Astron
Univ Arizona, Lunar & Planetary Lab
Keywordsplanets and satellites: atmospheres
planets and satellites: individual (WASP-4b)
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationAlex Bixel et al 2019 AJ 157 68
Rights© 2019. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractWe present an optical transmission spectrum of the atmosphere of WASP-4b obtained through observations of four transits with Magellan/IMACS, as part of the Arizona-CfA-Catolica-Carnegie Exoplanet Spectroscopy Survey (ACCESS). Using a Bayesian approach to atmospheric retrieval, we find no evidence for scattering or absorption features in our transit spectrum. Our models include a component to model the transit light source effect (spectral contamination from unocculted spots on the stellar photosphere), which we show can have a marked impact on the observed transmission spectrum for reasonable spot-covering fractions (<5%); this is the first such analysis for WASP-4b. We are also able to fit for the size and temperature contrast of spots observed during the second and third transits, finding evidence for both small, cool and large, warm spot-like features on the photosphere. Finally, we compare our results to those published by Huitson et al. using Gemini/GMOS and May et al. using IMACS, and we find that our data are in agreement.
VersionFinal published version
SponsorsNASA's Science Mission Directorate; NASA Earth and Space Science Fellowship Program [80NSS-C17K0470]; National Science Foundation Graduate Research Fellowship Program [DGE-1143953]; FONDECYT ; CONICYT [BASAL AFB-170002]; Ministry for the Economy, Development, and Tourism's Programa Iniciativa Cientifica Milenio [IC 120009]