Please use this identifier to cite or link to this item:
http://hdl.handle.net/20.500.12666/752
Title: | HST PanCET Program: A Complete Near-UV to Infrared Transmission Spectrum for the Hot Jupiter WASP-79b |
Authors: | Rathcke, A. D. MacDonald, R. J. Barstow, J. K. Goyal, J. M. López Morales, M. Mendoça, J. M. Sanz Forcada, J. Henry, G. W. Sing, D. K. Alam, M. K. |
Keywords: | Exoplanet atmospheres;Exoplanets atmospheric composition;Observational astronomy;Hot Jupiters;Transmission spectroscopy |
Issue Date: | 10-Sep-2021 |
Publisher: | IOP Science Publishing |
DOI: | 10.3847/1538-3881/ac0e99 |
Published version: | https://iopscience.iop.org/article/10.3847/1538-3881/ac0e99 |
Citation: | The Astronomical Journal 162(4): 138(2021) |
Abstract: | We present a new optical transmission spectrum of the hot Jupiter WASP-79b. We observed three transits with the STIS instrument mounted on the Hubble Space Telescope (HST), spanning 0.3–1.0 μm. Combining these transits with previous observations, we construct a complete 0.3–5.0 μm transmission spectrum of WASP-79b. Both HST and ground-based observations show decreasing transit depths toward blue wavelengths, contrary to expectations from Rayleigh scattering or hazes. We infer atmospheric and stellar properties from the full near-UV to infrared transmission spectrum of WASP-79b using three independent retrieval codes, all of which yield consistent results. Our retrievals confirm previous detections of H2O (at 4.0σ confidence) while providing moderate evidence of H− bound–free opacity (3.3σ) and strong evidence of stellar contamination from unocculted faculae (4.7σ). The retrieved H2O abundance (∼1%) suggests a superstellar atmospheric metallicity, though stellar or substellar abundances remain consistent with present observations (O/H = 0.3–34× stellar). All three retrieval codes obtain a precise H− abundance constraint: log(${X}_{{{\rm{H}}}^{-}}$) ≈ −8.0 ± 0.7. The potential presence of H− suggests that James Webb Space Telescope observations may be sensitive to ionic chemistry in the atmosphere of WASP-79b. The inferred faculae are ∼500 K hotter than the stellar photosphere, covering ∼15% of the stellar surface. Our analysis underscores the importance of observing UV–optical transmission spectra in order to disentangle the influence of unocculted stellar heterogeneities from planetary transmission spectra. |
URI: | http://hdl.handle.net/20.500.12666/752 |
E-ISSN: | 1538-4357 |
ISSN: | 0004-637X |
Appears in Collections: | (CAB) Artículos |
Files in This Item:
File | Description | Size | Format | |
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HST Pancet Program, a complete near UV to infrared transmission spectrum for the Hot Jupiter WASP 79b.pdf | 5,78 MB | Adobe PDF | View/Open |
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