Abstract
High-resolution Doppler-resolved spectroscopy has opened up a new window
into the atmospheres of both transiting and non-transiting exoplanets.
Here, we present VLT/UVES observations of a transit of WASP-121b, an
`ultra-hot' Jupiter previously found to exhibit a temperature inversion
and detections of multiple species at optical wavelengths. We present
initial results using the blue arm of UVES (≈3700-5000 Å),
recovering a clear signal of neutral Fe in the planet's atmosphere at
>8 σ, which could contribute to (or even fully explain) the
temperature inversion in the stratosphere. However, using standard
cross-correlation methods, it is difficult to extract physical
parameters such as temperature and abundances. Recent pioneering efforts
have sought to develop likelihood `mappings' that can be used to
directly fit models to high-resolution data sets. We introduce a new
framework that directly computes the likelihood of the model fit to the
data, and can be used to explore the posterior distribution of
parametrised model atmospheres via MCMC techniques. Our method also
recovers the physical extent of the atmosphere, as well as account for
time- and wavelength-dependent uncertainties. We measure a temperature
of 3710^{+490}_{-510} K, indicating a higher temperature in the upper
atmosphere when compared to low-resolution observations. We also show
that the Fe I signal is physically separated from the exospheric Fe II.
However, the temperature measurements are highly degenerate with aerosol
properties; detection of additional species, using more sophisticated
atmospheric models, or combining these methods with low-resolution
spectra should help break these degeneracies.
Original language | English |
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Pages (from-to) | 2215-2228 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 493 |
Issue number | 2 |
Early online date | 29 Jan 2020 |
DOIs | |
Publication status | Published - 01 Apr 2020 |
Keywords
- methods: data analysis
- techniques: spectroscopic
- stars: individual (WASP-121)
- planetary systems
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Dive into the research topics of 'Detection of Fe I in the atmosphere of the ultra-hot Jupiter WASP-121b, and a new likelihood-based approach for Doppler-resolved spectroscopy'. Together they form a unique fingerprint.Student theses
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High resolution Doppler spectroscopy of a transiting ultra-hot Jupiter at optical wavelengths
Merritt, S. (Author), Gibson, N. (Supervisor), Watson, C. (Supervisor) & de Mooij, E. (Supervisor), Dec 2021Student thesis: Doctoral Thesis › Doctor of Philosophy
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