[P-AE18] Exoplanets

[PAE18-07] The Transmission Spectrum of KELT-20b with HDS/Subaru and GRACES/Gemini-N: New Detections and the Fe I Double-Peak Mystery

*Stevanus Kristianto Nugroho^1,2, Ernst de Mooij³, Neale Gibson⁴, Vivien Parmentier⁵, Niall Owens³, Cathal Maguire⁶, Hajime Kawahara^7,8, Joost Wardenier⁹, Yui Kawashima^10,11,7,12, Teruyuki Hirano^1,2,13, Masayuki Kuzuhara^1,2, Takayuki Kotani^1,2,13, Kento Masuda¹⁴, Christopher Watson³, Swaetha Ramkumar⁴, Sayyed Ali Rafi⁸, Takeru Nakajima⁸, Motohide Tamura^8,1,2 (1.Astrobiology Center, 2.National Astronomical Observatory of Japan, 3.Queen's University Belfast, 4.Trinity College Dublin, 5.Université Côte d’Azur, 6.University of Bristol, 7.JAXA/ISAS, 8.University of Tokyo, 9.University of Montreal, 10.Kyoto University, 11.Tohoku University, 12.RIKEN, 13.SOKENDAI, 14.Osaka University)

Keywords:Hot Jupiter, Atmospheric chemistry, Atmospheric dynamics, High-resolution spectroscopy, Transmission spectroscopy

It has been more than three decades since the first exoplanet was discovered. Since then we have identified more than 5800 exoplanets in our galaxy alone. We have learned to characterize their atmospheres by detecting various chemical species in emission and transmission constraining chemical abundances and attempting to infer their planetary formation histories. With advances in stabilized spectrographs space telescopes like JWST and upcoming extremely large telescopes (ELTs) exoplanet atmospheres are being revealed in unprecedented three-dimensional detail marking the dawn of a new era in atmospheric studies.In this poster I will present our preliminary results on the transmission spectrum of KELT-20b observed using HDS/Subaru and GRACES/Gemini-N. We report new detections of Ca I, Cr I, K I, Sc II, and Sr II along with confirmations of previously identified species such as Fe I, Fe II, Na I, Ca II, Cr II, and Mg I. Leveraging the high spectral resolution of HDS (R~165,000) we confirmed that only Fe I exhibits a double-peak feature among the detected species. Importantly this demonstrates that the double peak is not an instrumental artefact but is intrinsic to the exoplanet’s atmosphere as it is consistently observed using four different facilities and at least six separate transit epochs. This finding offers potential insights into the atmospheric dynamics or chemical structure of KELT-20b.