collaborators

10 papers

astro-ph.EP2026

On the Reparameterization Between Cartesian Position-Velocity Vectors and Orbital Elements in the Kepler Problem

Kento Masuda, Kansuke Nunota

Reparameterization from the standard set of orbital elements to Cartesian position-velocity vectors can be computationally advantageous for orbit inference problems, particularly w…

astro-ph.EP2026

Bayesian Doppler Imaging: Simultaneous Inference of Surface Maps and Geometric Parameters

Yamato Ureshino, Hajime Kawahara, Hibiki Yama +1

We present a fully Bayesian, pixel-based Doppler imaging framework that enables the simultaneous inference of surface brightness maps and geometric parameters, including the inclin…

astro-ph.EP2026

ExoJAX Retrievals of VLT/CRIRES Spectra of Luhman 16AB: C/O Ratios and Systematic Uncertainties

Hibiki Yama, Kento Masuda, Yui Kawashima +1

We present atmospheric retrievals of the benchmark brown dwarf binary Luhman 16AB using high-resolution VLT/CRIRES spectra and the differentiable framework ExoJAX. We derive elemen…

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…