Rathcke, AD;
MacDonald, RJ;
Barstow, JK;
Goyal, JM;
Lopez-Morales, M;
Mendonça, JM;
Sanz-Forcada, J;
... Buchhave, LA; + view all
(2021)
HST PanCET Program: A Complete Near-UV to Infrared Transmission Spectrum for the Hot Jupiter WASP-79b.
The Astronomical Journal
, 162
(4)
, Article 138. 10.3847/1538-3881/ac0e99.
Preview |
Text
Rathcke_2021_AJ_162_138.pdf - Published Version Download (5MB) | Preview |
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 - 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.
| Type: | Article |
|---|---|
| Title: | HST PanCET Program: A Complete Near-UV to Infrared Transmission Spectrum for the Hot Jupiter WASP-79b |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-3881/ac0e99 |
| Publisher version: | https://doi.org/10.3847/1538-3881/ac0e99 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10134951 |
Loading...
Loading...Loading...| 1. |  United States | 1 |
| 2. |  Indonesia | 1 |
| 3. |  Australia | 1 |
| 4. |  Russian Federation | 1 |
Archive Staff Only
 |
View Item |
