S. Vievard

A Search for helium in the atmospheres of three sub-Neptunes and a super-Earth around M-dwarfs

Kiyoe Kawauchi, Norio Narita, Yuichi Ito +26

Thousands of sub-Neptunes have been discovered mainly through space-based surveys such as Kepler and TESS. Their bulk compositions and internal structures are thought to reflect th…

SCExAO/CHARIS High-Contrast Pre-Launch Vetting of Roman Coronagraph Technology Demonstration PSF Reference Stars

Thayne Currie, Jie Li, Mona El Morsy +9

We present deep, SCExAO/CHARIS high-contrast integral field spectroscopy and archival imaging of four candidate Roman Coronagraph PSF reference stars within/near the Roman Continuo…

Technology and Science Advancing Observations with Roman Coronagraph Informed by Ground-Based High-Contrast Imaging

Mona El Morsy, Thayne Currie, Brianna Lacy +10

The Roman Coronagraph technology demonstration focuses on achieving $<$ 10 $^{- 7}$ contrasts within the instrument's dark hole and our ability to detect and characterize properties…

The mass of TOI-1883 b: A low density super-Neptune in the ridge regime transiting an early-M dwarf

Izuru Fukuda, Norio Narita, Akihiko Fukui +36

Recent large-scale transit surveys conducted by space telescopes such as Kepler and TESS have revealed a vast number of exoplanets, uncovering the diversity of their population. On…

astro-ph.EP2025★ 3 cited

SCExAO/CHARIS and Gaia Direct Imaging and Astrometric Discovery of a Superjovian Planet 3--4 lambda/D from the Accelerating Star HIP 54515

Thayne Currie, Yiting Li, Mona El Morsy +28

We present the discovery of a superjovian planet around the young A5 star HIP 54515, detected using precision astrometry from the Hipparcos Gaia Catalogue of Accelerations and high…

Multi-band Spectral and Astrometric Characterization of the HIP 99770 b Planet with SCExAO/CHARIS and Gaia

Danielle Bovie, Thayne Currie, Mona El Morsy +12

We present and analyze follow-up, higher resolution ( $R$ $\sim$ 70) $H$ and $K$ band integral field spectroscopy of the superjovian exoplanet HIP 99770 b with SCExAO/CHARIS. Our ne…

Dynamical Analysis of the HD 169142 Planet-Forming Disk: Twelve Years of High-Contrast Polarimetry

Miles Lucas, Michael Bottom, Ruobing Dong +19

We present a dynamical analysis of the HD 169142 planet-forming disk based on high-contrast polarimetric imaging over a twelve-year observational period, offering insights into its…

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…

The mass of TOI-654 b: A short-period sub-Neptune transiting a mid-M dwarf

Kai Ikuta, Norio Narita, Takuya Takarada +40

Sub-Neptunes are small planets between the size of the Earth and Neptune. The orbital and bulk properties of transiting sub-Neptunes can provide clues for their formation and evolu…

SCExAO/CHARIS Near-Infrared Scattered-Light Imaging and Integral Field Spectropolarimetry of the AB Aurigae Protoplanetary System

Erica Dykes, Thayne Currie, Kellen Lawson +21

We analyze near-infrared integral field spectropolarimetry of the AB Aurigae protoplanetary disk and protoplanet (AB Aur b), obtained with SCExAO/CHARIS in 22 wavelength channels c…

Design, scientific goals, and performance of the SCExAO survey for planets around accelerating stars

Mona El Morsy, Thayne Currie, Masayuki Kuzuhara +25

We describe the motivation, design, and early results for our 42-night, 125 star Subaru/SCExAO direct imaging survey for planets around accelerating stars. Unlike prior large surve…

astro-ph.EP2024★ 22 cited

Dynamical and Atmospheric Characterization of the Substellar Companion HD 33632 Ab from Direct Imaging, Astrometry, and Radial-Velocity Data

Mona El Morsy, Thayne Currie, Danielle Bovie +17

We present follow-up SCExAO/CHARIS $H$ and $K$ -band (R $\sim$ 70) high-contrast integral field spectroscopy and Keck/NIRC2 photometry of directly-imaged brown dwarf companion HD 33…

Gliese 12 b: A temperate Earth-sized planet at 12 pc ideal for atmospheric transmission spectroscopy

M. Kuzuhara, A. Fukui, J. H. Livingston +103

Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the atmospheres of terrestrial planets via follow-up spectroscopic observ…

The Discovery and Follow-up of Four Transiting Short-period Sub-Neptunes Orbiting M dwarfs

Y. Hori, A. Fukui, T. Hirano +100

Sub-Neptunes with $2 - 3 R_{\oplus}$ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes pr…

SCExAO/CHARIS Multi-Wavelength, High-Contrast Imaging of the BD+45 $^{\circ}$ 598 Debris Disk

Maria Vincent, Kellen Lawson, Thayne Currie +5

We present a multi-wavelength (1.16 $μ$ m-2.37 $μ$ m) view of the debris disk around BD+45 $^{\circ}$ 598, using the Subaru Coronagraphic Extreme Adaptive Optics system paired with the Cor…

Transit Spectroscopy of K2-33b with Subaru/IRD: Spin-Orbit Alignment and Tentative Atmospheric Helium

Teruyuki Hirano, Eric Gaidos, Hiroki Harakawa +13

Exoplanets in their infancy are ideal targets to probe the formation and evolution history of planetary systems, including the planet migration and atmospheric evolution and dissip…