activity
20242026
collaborators

5 papers

astro-ph.IM2026

PyIRD: A Python-Based Data Reduction Pipeline for Subaru/IRD and REACH

Yui Kasagi, Hajime Kawahara, Ziying Gu +4

PyIRD is a Python-based pipeline for reducing spectroscopic data obtained with IRD (InfraRed Doppler; Kotani et al. (2018)) and REACH (Rigorous Exoplanetary Atmosphere Characteriza…

astro-ph.EP2025

Unveiling the Atmosphere of HR 7672 B from the Near-Infrared High-Resolution Spectrum Using REACH/Subaru

Yui Kasagi, Yui Kawashima, Hajime Kawahara +12

Characterizing the atmospheres of exoplanets and brown dwarfs is crucial for understanding their atmospheric physics and chemistry, searching for biosignatures, and investigating t…

astro-ph.EP2025

Atmospheric retrieval of Subaru/IRD high-resolution spectrum of the archetype T-type brown dwarf Gl 229 B

Yui Kawashima, Hajime Kawahara, Yui Kasagi +14

Brown dwarfs provide a unique opportunity to study atmospheres and their physical and chemical processes with high precision, especially in temperature ranges relevant to exoplanet…

astro-ph.EP2025

Differentiable Modeling of Planet and Substellar Atmosphere: High-Resolution Emission, Transmission, and Reflection Spectroscopy with ExoJAX2

Hajime Kawahara, Yui Kawashima, Shotaro Tada +11

Modeling based on differentiable programming holds great promise for astronomy, enabling advanced techniques such as gradient-based posterior sampling and optimization. This paradi…

astro-ph.SR2024

Weighing Single-lined Spectroscopic Binaries Using Tidal Effects on Radial Velocities: The Case of V723 Monocerotis

Mio Tomoyoshi, Kento Masuda, Teruyuki Hirano +6

In single-lined spectroscopic binaries (SB1s) where flux variations due to tidal deformation of the primary star (ellipsoidal variations, EVs) are detected, the binary mass can be…