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

Autor: Pino, L., Brogi, M., Désert, J. M., Nascimbeni, V., Bonomo, A. S., Rauscher, E., Basilicata, M., Biazzo, K., Bignamini, A., Borsa, F., Claudi, R., Covino, E., Di Mauro, M. P., Guilluy, G., Maggio, A., Malavolta, L., Micela, G., Molinari, E., Molinaro, M., Montalto, M., Nardiello, D., Pedani, M., Piotto, G., Poretti, E., Rainer, M., Scandariato, G., Sicilia, D., Sozzetti, A.
Rok vydání: 2022
Předmět:
Zdroj: A&A 668, A176 (2022)
Druh dokumentu: Working Paper
DOI: 10.1051/0004-6361/202244593
Popis: [Abridged] We present a novel method to study the thermal emission of exoplanets as a function of orbital phase at very high spectral resolution, and apply it to investigate the climate of the ultra-hot Jupiter KELT-9b. We combine 3 nights of HARPS-N and 2 nights of CARMENES optical spectra, covering orbital phases between quadratures (0.25 < phi < 0.75), when the planet shows its day-side hemisphere with different geometries. We co-add the signal of thousands of FeI lines through cross-correlation, which we map to a likelihood function. We investigate the phase-dependence of: (i) the line depths of FeI, and (ii) their Doppler shifts, by introducing a new method that exploits the very high spectral resolution of our observations. We confirm a previous detection of FeI emission and demonstrate a combined precision of 0.5 km s-1 on the orbital properties of KELT-9b. By studying the phase-resolved Doppler shift of FeI lines, we detect an anomaly in the planet's orbital radial velocity well-fitted with a slightly eccentric orbit (e = 0.016$\pm$0.003, w = 150$^{+13\circ}_{-11},~5\sigma$ preference). However, we argue that such anomaly can be explained by a day-night wind of a few km s-1 blowing neutral iron gas. Additionally, we find that the FeI emission line depths are symmetric around the substellar point within 10 deg ($2\sigma$). We show that these results are qualitatively compatible with predictions from general circulation models for ultra-hot Jupiter planets. Very high-resolution spectroscopy phase curves have the sensitivity to reveal a phase dependence in both the line depths and their Doppler shifts throughout the orbit. They are highly complementary to space-based phase curves obtained with HST and JWST, and open a new window into the still poorly understood climate and atmospheric structure of the hottest planets known.
Comment: Recommended for publication on A&A after referee report, awaiting acceptance. 25 pages, 19 figures, 3 tables
Databáze: arXiv
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