Exoplanets & Exomoons

The PEPSI Exoplanet Transit Survey (PETS). V: New Na D Transmission Spectra Indicate A Quieter Atmosphere On HD 189733b

By Keith Cowing
Status Report
April 23, 2024
Filed under , , , , , , , , ,
The PEPSI Exoplanet Transit Survey (PETS). V: New Na D Transmission Spectra Indicate A Quieter Atmosphere On HD 189733b
2D color map showing the transmission spectra – 1 divided by the out-of-transit column standard deviation at each pixel at different orbital phases for the Na d2 line (top) and Na d1 line (bottom) in the stellar restframe. Cyan dashed lines mark the 1st – 4th contact and the purple dashed lines mark the 2nd – 3rd contact. The black dashed lines illustrate the planetary absorption trajectory. Left: Transmission spectra before correcting with RM-CLV-model. Right: Transmission spectra corrected with the RM-CLV-model. — astro-ph.EP

Absorption lines from exoplanet atmospheres observed in transmission allow us to study atmospheric characteristics such as winds.

We present a new high-resolution transit time-series of HD 189733b, acquired with the PEPSI instrument at the LBT and analyze the transmission spectrum around the Na D lines. We model the spectral signature of the RM-CLV-effect using synthetic PHOENIX spectra based on spherical LTE atmospheric models.

We find a Na D absorption signature between the second and third contact but not during the ingress and egress phases, which casts doubt on the planetary origin of the signal. Presupposing a planetary origin of the signal, the results suggest a weak day-to-nightside streaming wind in the order of 0.7 km/s and a moderate super-rotational streaming wind in the order of 3 – 4 km/s, challenging claims of prevailing strong winds on HD 189733b.

E. Keles, S. Czesla, K. Poppenhaeger, P. Hauschildt, T. A. Carroll, I. Ilyin, M. Baratella, M. Steffen, K. G. Strassmeier, A. S. Bonomo, B. S. Gaudi, T. Henning, M. C. Johnson, K. Molaverdikhani, V. Nascimbeni, J. Patience, A. Reiners, G. Scandariato, E. Schlawin, E. Shkolnik, D. Sicilia, A. Sozzetti, M. Mallonn, C. Veillet, J. Wang, F. Yan

Comments: Accepted for publication in Monthly Notices of the Royal Astronomical Society
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2404.13586 [astro-ph.EP] (or arXiv:2404.13586v1 [astro-ph.EP] for this version)
Submission history
From: Engin Keles
[v1] Sun, 21 Apr 2024 08:53:57 UTC (5,326 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻