A SEA BASS on the exoplanet HD209458b

Giuseppe Morello
(Submitted on 26 Dec 2017)

We present the first application of SEA BASS: Stellar and Exoplanetary Atmospheres Bayesian Analysis Simultaneous Spectroscopy. It is an optimised scheme that enables simultaneous derivation of four-coefficient stellar limb-darkening profiles, transit depths and orbital parameters from exoplanetary transits observed at multiple wavelengths. The key assumptions are the wavelength-independence of the system geometry and the reduced limb-darkening effect in the infrared. This approach has been tested by \cite{morello17} with synthetic datasets. In this paper, we improve on the original algorithm by using multiple \textit{Spitzer}/IRAC passbands and a more effective set of geometric parameters. We demonstrate the ability to measure the HD209458 limb-darkening profile over multiple passbands in the range 290–570 nm from \textit{HST}/STIS observations with sufficient accuracy to rule out some theoretical models adopted in the previous literature, and simultaneously extract the transmission spectrum of the exoplanet atmosphere. The higher photometric precision of next-generation instruments, such as those onboard James Webb Space Telescope (JWST), will enable modelling of the star-planet systems with unprecedented detail, and increase the importance of the SEA BASS approach to avoid the potential biases introduced by inaccurate stellar limb-darkening models.

Comments:    submitted to AJ
Subjects:    Earth and Planetary Astrophysics (astro-ph.EP)
Cite as:    arXiv:1712.09393 [astro-ph.EP] (or arXiv:1712.09393v1 [astro-ph.EP] for this version)
Submission history
From: Giuseppe Morello
[v1] Tue, 26 Dec 2017 20:21:58 GMT (894kb)
https://arxiv.org/abs/1712.09393