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Subaru Seminars are
usually held in Room 104 of the Hilo Base Facility, adjacent
to the main lobby. Everyone is welcome to attend. If you would like to
give a seminar, please contact Subaru seminar organizers
(Rusu Cristian Eduard, Tae-Soo Pyo, Nagayoshi Ohashi)
by email : sseminar_at_subaru.naoj.org (please change"_at" to @).
February 13, Wednesday, 11am in 104A
Characterisation of Exoplanet Atmosphere using High-resolution Spectroscopy: Searching for TiO Signature in the Atmosphere of WASP-33b
Stevanus Kristianto Nugroho (Tohoku University)
Abstract: Recently, direct detection of the molecular signature in exoplanet atmosphere using high-resolution spectroscopy is a hot topic in the exoplanet characterisation research field. Unlike low-resolution spectroscopy, it is able to resolve molecular bands into individual absorption lines. By observing the planet during its orbital movement, it is possible to distinguish the exoplanet lines from telluric and stellar lines owing to the variation of Doppler shifts and detect specific molecule unambiguously, which is why it is called planet radial velocity (PRV) technique. It has been predicted that titanium oxide (TiO) and/or vanadium oxide (VO) causing thermal inversions in the atmosphere of the the very hot Jupiters. To find the thermal inversion agent, we observed WASP-33 b before its secondary eclipse using High Dispersion Spectrograph (HDS; R~165,000) on Subaru telescope in the wavelength range of 0.62-0.88 µm. We remove the systematics from the instrument, the telluric and stellar lines using SYSREM and cross-correlate it with model spectrum. We are able to detect TiO emission signature and confirm the existence of stratosphere in the dayside atmosphere of WASP-33b (one of the hottest Hot Jupiter, Teq= 3300 K) by 4.8 sigma. This is the first direct detection of TiO emission signature in the dayside of exoplanet atmosphere using PRV technique in the optical wavelength regime. Our result strengthens the prediction that cold trap effect is inefficient in the atmosphere of a very hot jupiter (Teq > 2500K) and demonstrate the capability of HDS on Subaru telescope to do PRV observation.