The GAPS Programme at TNG. XLI. The climate of KELT-9b revealed with a new approach to high-spectral-resolution phase curves - Archive ouverte HAL
Article Dans Une Revue Astronomy & Astrophysics - A&A Année : 2022

The GAPS Programme at TNG. XLI. The climate of KELT-9b revealed with a new approach to high-spectral-resolution phase curves

L. Pino
  • Fonction : Auteur
M. Brogi
  • Fonction : Auteur
J. M. Désert
  • Fonction : Auteur
V. Nascimbeni
  • Fonction : Auteur
A. S. Bonomo
  • Fonction : Auteur
E. Rauscher
  • Fonction : Auteur
M. Basilicata
  • Fonction : Auteur
K. Biazzo
  • Fonction : Auteur
A. Bignamini
  • Fonction : Auteur
F. Borsa
  • Fonction : Auteur
R. Claudi
  • Fonction : Auteur
E. Covino
  • Fonction : Auteur
M. P. Di Mauro
  • Fonction : Auteur
G. Guilluy
  • Fonction : Auteur
A. Maggio
  • Fonction : Auteur
L. Malavolta
  • Fonction : Auteur
G. Micela
  • Fonction : Auteur
E. Molinari
  • Fonction : Auteur
M. Molinaro
  • Fonction : Auteur
M. Montalto
  • Fonction : Auteur
M. Pedani
  • Fonction : Auteur
G. Piotto
  • Fonction : Auteur
E. Poretti
  • Fonction : Auteur
M. Rainer
  • Fonction : Auteur
G. Scandariato
  • Fonction : Auteur
D. Sicilia
  • Fonction : Auteur
A. Sozzetti
  • Fonction : Auteur

Résumé


Aims: We present a novel method for studying the thermal emission of exoplanets as a function of orbital phase at very high spectral resolution, and use it to investigate the climate of the ultra-hot Jupiter KELT-9b.
Methods: We combine three nights of HARPS-N and two nights of CARMENES optical spectra, covering orbital phases between quadratures (0.25 < φ < 0.75), when the planet shows its day-side hemisphere with different geometries. We co-add the signal of thousands of Fe I lines through cross-correlation, which we map to a likelihood function. We investigate the phase-dependence of two separate observable quantities, namely (i) the line depths of Fe I and (ii) their Doppler shifts, introducing a new method that exploits the very high spectral resolution of our observations.
Results: We confirm a previous detection of Fe I emission, and demonstrate a precision of 0.5 km s−1 on the orbital properties of KELT-9b when combining all nights of observations. By studying the phase-resolved Doppler shift of Fe I lines, we detect an anomaly in the planet's orbital radial velocity well-fitted with a slightly eccentric orbital solution (e = 0.016 ± 0.003, ω = 150−11+13°, 5σ preference). However, we argue that this anomaly is caused by atmospheric circulation patterns, and can be explained if neutral iron gas is advected by day-to-night atmospheric wind flows of the order of a few km s−1. We additionally show that the Fe I emission line depths are symmetric around the substellar point within 10° (2σ), possibly indicating the lack of a large hot-spot offset at the altitude probed by neutral iron emission lines. Finally, we do not obtain a significant preference for models with a strong phase-dependence of the Fe I emission line strength. We show that these results are qualitatively compatible with predictions from general circulation models (GCMs) for ultra-hot Jupiter planets.
Conclusions: Very high-resolution spectroscopy phase curves are of sufficient sensitivity to reveal a phase dependence in both the line depths and their Doppler shifts throughout the orbit. They constitute an under-exploited treasure trove of information that is highly complementary to space-based phase curves obtained with HST and JWST, and open a new window onto the still poorly understood climate and atmospheric structure of the hottest planets known to date.
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hal-03935711 , version 1 (18-01-2023)

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L. Pino, M. Brogi, J. M. Désert, V. Nascimbeni, A. S. Bonomo, et al.. The GAPS Programme at TNG. XLI. The climate of KELT-9b revealed with a new approach to high-spectral-resolution phase curves. Astronomy & Astrophysics - A&A, 2022, 668, ⟨10.1051/0004-6361/202244593⟩. ⟨hal-03935711⟩

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