ACCESS: Ground-based Optical Transmission Spectroscopy of the Hot Jupiter WASP-4b

被引:23
作者
Bixel, Alex [1 ,2 ]
Rackham, Benjamin, V [1 ,2 ]
Apai, Daniel [1 ,2 ,3 ]
Espinoza, Nestor [4 ,5 ,6 ]
Lopez-Morales, Mercedes [2 ,7 ]
Osip, David [8 ]
Jordan, Andres [2 ,4 ,5 ,6 ]
McGruder, Chima [7 ]
Weaver, Ian [7 ]
机构
[1] Univ Arizona, Steward Observ, Dept Astron, 933 N Cherry Ave, Tucson, AZ 85721 USA
[2] NASA, Earths Other Solar Syst Team, Nexus Exoplanet Syst Sci, Washington, DC 20546 USA
[3] Univ Arizona, Lunar & Planetary Lab, 1640 E Univ Blvd, Tucson, AZ 85721 USA
[4] Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany
[5] Pontificia Univ Catolica Chile, Fac Fis, Inst Astrofis, Av Vicuna Mackenna 4860, Santiago 7820436, Chile
[6] Millennium Inst Astrophys, Av Vicuna Mackenna 4860, Santiago 7820436, Chile
[7] Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 01238 USA
[8] Carnegie Inst Sci, Las Campanas Observ, Casilla 601, La Serena, Chile
基金
美国国家科学基金会;
关键词
planets and satellites: atmospheres; planets and satellites: individual (WASP-4b); stars: activity; starspots; techniques: spectroscopic; EXOPLANET HD 189733B; EXTRASOLAR PLANET; ATMOSPHERIC HAZE; LIGHT CURVES; SPECTRA; MODEL; PARAMETERS; HUBBLE; PHOTOMETRY; TRANSITS;
D O I
10.3847/1538-3881/aaf9a3
中图分类号
P1 [天文学];
学科分类号
0704 ;
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-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.
引用
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页数:27
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