文章基本信息

标题：ACCESS: Ground-based Optical Transmission Spectroscopy of the Hot Jupiter WASP-4b
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作者：Alex Bixel ; Benjamin V. Rackham ; Dániel Apai 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2019
卷号：157
期号：2
页码：1-27
DOI：10.3847/1538-3881/aaf9a3
语种：English
出版社：American Institute of Physics
摘要：We 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-Católica-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.
关键词：planets and satellites: atmospheres;planets and satellites: individual (WASP-4b);stars: activity;starspots;techniques: spectroscopic