133 citations · 1.1k across the 29 of their papers we have counts for
24 papers · 1 filter
A Fourth Planet in the Kepler-51 System Revealed by Transit Timing Variations
Kento Masuda, Jessica E. Libby-Roberts, John H. Livingston +49
Kepler-51 is a -old Sun-like star hosting three transiting planets with radii - and orbital periods -$130\,\mathrm{day…
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…
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…
First Comparative Exoplanetology Within a Transiting Multi-planet System: Comparing the atmospheres of V1298 Tau b and c
Saugata Barat, Jean-Michel Désert, Jayesh M. Goyal +13
The V1298 Tau system (20-30Myr), is a benchmark young multi-planet system that provides the opportunity to perform comparative exoplanetology between planets orbiting the same star…
A spectroscopic thermometer: individual vibrational band spectroscopy with the example of OH in the atmosphere of WASP-33b
Sam O. M. Wright, Stevanus K. Nugroho, Matteo Brogi +26
Individual vibrational band spectroscopy presents an opportunity to examine exoplanet atmospheres in detail by distinguishing where the vibrational state populations of molecules d…
Investigation of the upper atmosphere in ultra-hot Jupiter WASP-76 b with high-resolution spectroscopy
Kiyoe Kawauchi, Norio Narita, Bun'ei Sato +1
Alkali metal lines are one of the most important key opacity sources for understanding exoplanetary atmospheres because the Na I resonance doublets are thought to be the cause of l…
Implementation of disequilibrium chemistry to spectral retrieval code ARCiS and application to sixteen exoplanet transmission spectra: Indication of disequilibrium chemistry for HD 209458b and WASP-39b
Yui Kawashima, Michiel Min
The retrieval approach is currently a standard method for deriving atmospheric properties from observed spectra of exoplanets. However, the approach ignores disequilibrium chemistr…
Auto-Differentiable Spectrum Model for High-Dispersion Characterization of Exoplanets and Brown Dwarfs
Hajime Kawahara, Yui Kawashima, Kento Masuda +3
We present an auto-differentiable spectral modeling of exoplanets and brown dwarfs. This model enables a fully Bayesian inference of the high--dispersion data to fit the ab initio…
First Detection of Hydroxyl Radical Emission from an Exoplanet Atmosphere: High-dispersion Characterization of WASP-33b using Subaru/IRD
Stevanus K. Nugroho, Hajime Kawahara, Neale P. Gibson +23
We report the first detection of a hydroxyl radical (OH) emission signature in the planetary atmosphere outside the solar system, in this case, in the day-side of WASP-33b. We anal…
Neutral metals in the atmosphere of HD149026b
Masato Ishizuka, Hajime Kawahara, Stevanus K. Nugroho +3
Recent progress in high-dispersion spectroscopy has revealed the presence of vaporized heavy metals and ions in the atmosphere of hot Jupiters whose dayside temperature is larger t…
The ARCiS framework for Exoplanet Atmospheres: Modelling Philosophy and Retrieval
Michiel Min, Chris W. Ormel, Katy Chubb +2
Aims: ARCiS, a novel code for the analysis of exoplanet transmission and emission spectra is presented. The aim of the modelling framework is to provide a tool able to link observa…
Obliquity measurement and atmospheric characterization of the WASP-74 planetary system
R. Luque, N. Casasayas-Barris, H. Parviainen +27
We present new transit observations of the hot Jupiter WASP-74 b ( 1860 K) using the high-resolution spectrograph HARPS-N and the multi-colour simultaneous imag…
Tentative Evidence for Water Vapor in the Atmosphere of the Neptune-Size Exoplanet HD 106315 c
Laura Kreidberg, Paul Mollière, Ian J. M. Crossfield +27
We present a transmission spectrum for the Neptune-size exoplanet HD 106315 c from optical to infrared wavelengths based on transit observations from the Hubble Space Telescope/Wid…
Super-Rayleigh Slopes in Transmission Spectra of Exoplanets Generated by Photochemical Haze
Kazumasa Ohno, Yui Kawashima
Spectral slopes in optical transmission spectra of exoplanetary atmospheres encapsulate information on the properties of exotic clouds. The slope is usually attributed to the Rayle…
Aluminium oxide in the atmosphere of hot Jupiter WASP-43b
Katy L. Chubb, Michiel Min, Yui Kawashima +2
We have conducted a re-analysis of publicly available Hubble Space Telescope Wide Field Camera 3 (HST WFC3) transmission data for the hot-Jupiter exoplanet WASP-43b, using the Baye…
Theoretical Transmission Spectra of Exoplanet Atmospheres with Hydrocarbon Haze. II. Dependence on UV Irradiation Intensity, Metallicity, C/O Ratio, Eddy Diffusion Coefficient, and Temperature
Yui Kawashima, Masahiro Ikoma
Recent transmission spectroscopy has revealed that clouds and hazes are common in the atmospheres of close-in exoplanets. In this study, using the photochemical, microphysical, and…
Theoretical Reflectance Spectra of Earth-Like Planets through Their Evolutions: Impact of Clouds on the Detectability of Oxygen, Water, and Methane with Future Direct Imaging Missions
Yui Kawashima, Sarah Rugheimer
In the near-future, atmospheric characterization of Earth-like planets in the habitable zone will become possible via reflectance spectroscopy with future telescopes such as the pr…
Detectable molecular features above hydrocarbon haze via transmission spectroscopy with JWST: Case studies of GJ 1214b-, GJ 436b-, HD 97658b-, and Kepler-51b-like planets
Yui Kawashima, Renyu Hu, Masahiro Ikoma
Some of the exoplanets so far observed show featureless or flat transmission spectra, possibly indicating the existence of clouds and/or haze in their atmospheres. Thanks to its la…
Lowest Earth's atmosphere layers probed during a lunar eclipse
Kiyoe Kawauchi, Norio Narita, Bun'ei Sato +5
We report the results of detailed investigation of the Earth's transmission spectra during the lunar eclipse on UT 2011 December 10. The spectra were taken by using the High Disper…
Theoretical transmission spectra of exoplanet atmospheres with hydrocarbon haze: Effect of creation, growth, and settling of haze particles. I. Model description and first results
Yui Kawashima, Masahiro Ikoma
Recently, properties of exoplanet atmospheres have been constrained via multi-wavelength transit observation, which measures an apparent decrease in stellar brightness during plane…
Demonstrating High-precision, Multiband Transit Photometry with MuSCAT: A Case for HAT-P-14b
Akihiko Fukui, Norio Narita, Yui Kawashima +6
The Multicolor Simultaneous Camera for studying Atmospheres of Transiting exoplanets (MuSCAT) is an optical three-band (g'_2-, r'_2-, and z_{s,2}-band) imager that was recently dev…
Theoretical Emission Spectra of Atmospheres of Hot Rocky Super-Earths
Yuichi Ito, Masahiro Ikoma, Hajime Kawahara +3
Motivated by recent detection of transiting high-density super-Earths, we explore the detectability of hot rocky super-Earths orbiting very close to their host stars. In the enviro…
Multi-band, Multi-epoch Observations of the Transiting Warm Jupiter WASP-80b
Akihiko Fukui, Yui Kawashima, Masahiro Ikoma +22
WASP-80b is a warm Jupiter transiting a bright late-K/early-M dwarf, providing a good opportunity to extend the atmospheric study of hot Jupiters toward the lower temperature regim…
Multi-Color Transit Photometry of GJ 1214b through BJHKs-Bands and a Long-Term Monitoring of the Stellar Variability of GJ 1214
Norio Narita, Akihiko Fukui, Masahiro Ikoma +19
We present 5 new transit light curves of GJ 1214b taken in BJHKs-bands. Two transits were observed in B-band using the Suprime-Cam and the FOCAS instruments onboard the Subaru 8.2m…