672 citations · 5.3k across the 101 of their papers we have counts for
101 papers
GJ 367b: A dense ultra-short period sub-Earth planet transiting a nearby red dwarf star
Kristine W. F. Lam, Szilárd Csizmadia, Nicola Astudillo-Defru +75
Ultra-short-period (USP) exoplanets have orbital periods shorter than one day. Precise masses and radii of USPs could provide constraints on their unknown formation and evolution p…
Zodiacal Exoplanets in Time (ZEIT) XIII: Planet Orbits and Atmospheres in the V1298 Tau System, a Keystone in Studies of Early Planetary Evolution
E. Gaidos, T. Hirano, C. Beichman +16
Studies of planetary systems of stars in star-forming regions and young clusters open a window on the formative stages of planetary evolution. We obtained high-cadence high-resolut…
Zodiacal Exoplanets in Time (ZEIT) XII: A Directly-Imaged Planetary-Mass Companion to a Young Taurus M Dwarf Star
E. Gaidos, T. Hirano, A. L. Kraus +21
We report the discovery of a resolved (0".9) substellar companion to a member of the 1-5 Myr Taurus star-forming region. The host star (2M0437) is a single mid-M type ($T_{eff}\app…
TOI-2285b: A 1.7 Earth-radius Planet Near the Habitable Zone around a Nearby M Dwarf
Akihiko Fukui, Tadahiro Kimura, Teruyuki Hirano +60
We report the discovery of TOI-2285b, a sub-Neptune-sized planet transiting a nearby (42 pc) M dwarf with a period of 27.3 days. We identified the transit signal from the Transitin…
Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System
Bryson Cale, Michael Reefe, Peter Plavchan +52
We present updated radial-velocity (RV) analyses of the AU Mic system. AU Mic is a young (22 Myr) early M dwarf known to host two transiting planets - days, $R_{b}=…
Wavelength Dependence of Activity-Induced Photometric Variations for Young Cool Stars in Hyades
Kohei Miyakawa, Teruyuki Hirano, Akihiko Fukui +3
We investigate photometric variations due to stellar activity which induce systematic radial-velocity errors (so-called "jitter") for the four targets in the Hyades open cluster ob…
Joint Analysis of Multicolor Photometry: A New Approach to Constrain the Nature of Multiple-Star Systems Hosting Exoplanet Candidates
Kohei Miyakawa, Teruyuki Hirano, Bun'ei Sato +2
We present a new method to assess the properties of transiting planet candidates by multicolor photometry. By analyzing multicolor transit/eclipse light curves and apparent magnitu…
Hot planets around cool stars -- two short-period mini-Neptunes transiting the late K-dwarf TOI-1260
I. Y. Georgieva, C. M. Persson, O. Barragán +56
We present the discovery and characterization of two sub-Neptunes in close orbits, as well as a tentative outer planet of a similar size, orbiting TOI-1260 - a low metallicity K6V…
Tidal Effects on the Radial Velocities of V723 Mon: Additional Evidence for a Dark Companion
Kento Masuda, Teruyuki Hirano
Jayasinghe et al. (2021) identified a dark companion on a nearly edge-on orbit around the red giant star V723 Monoceros as a black h…
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…
Two Bright M Dwarfs Hosting Ultra-Short-Period Super-Earths with Earth-like Compositions
Teruyuki Hirano, John H. Livingston, Akihiko Fukui +58
We present observations of two bright M dwarfs (TOI-1634 and TOI-1685: ) hosting ultra-short period (USP) planets, identified by the TESS mission. The two stars are simi…
A backward-spinning star with two coplanar planets
Maria Hjorth, Simon Albrecht, Teruyuki Hirano +5
It is widely assumed that a star and its protoplanetary disk are initially aligned, with the stellar equator parallel to the disk plane. When observations reveal a misalignment bet…
Mass and density of the transiting hot and rocky super-Earth LHS 1478 b (TOI-1640 b)
M. G. Soto, G. Anglada-Escudé, S. Dreizler +52
One of the main objectives of the Transiting Exoplanet Survey Satellite ({TESS}) mission is the discovery of small rocky planets around relatively bright nearby stars. Here, we rep…
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…
Masses and compositions of three small planets orbiting the nearby M dwarf L231-32 (TOI-270) and the M dwarf radius valley
Vincent Van Eylen, N. Astudillo-Defru, X. Bonfils +69
We report on precise Doppler measurements of L231-32 (TOI-270), a nearby M dwarf ( pc, M, R), which hosts three transiting p…
Characterization of M dwarfs Using Optical Mid-Resolution Spectra for Exploration of Small Exoplanets
Yohei Koizumi, Masayuki Kuzuhara, Masashi Omiya +4
We present the optical spectra of 338 nearby M dwarfs, and compute their spectral types, effective temperatures (), and radii. Our spectra have been obtained usin…
A planetary system with two transiting mini-Neptunes near the radius valley transition around the bright M dwarf TOI-776
R. Luque, L. M. Serrano, K. Molaverdikhani +63
We report the discovery and characterization of two transiting planets around the bright M1 V star LP 961-53 (TOI-776, J = 8.5 mag, M = 0.54+-0.03 Msun) detected during Sector 10 o…
Precision radial velocity measurements by the forward-modeling technique in the near-infrared
Teruyuki Hirano, Masayuki Kuzuhara, Takayuki Kotani +15
Precision radial velocity (RV) measurements in the near-infrared are a powerful tool to detect and characterize exoplanets around low-mass stars or young stars with higher magnetic…
The TOI-763 system: sub-Neptunes orbiting a Sun-like star
M. Fridlund, J. Livingston, D. Gandolfi +51
We report the discovery of a planetary system orbiting TOI-763 (aka CD-39 7945), a , high proper motion G-type dwarf star that was photometrically monitored by the TESS spa…
Constraining the Bulk Composition of Disintegrating Exoplanets Using Combined Transmission Spectra from JWST and SPICA
Ayaka Okuya, Satoshi Okuzumi, Kazumasa Ohno +1
Disintegrating planets are ultra-short-period exoplanets that appear to have a comet-like dust tail. They are commonly interpreted as low-mass planets whose solid surface is evapor…
Zodiacal Exoplanets in Time. XI. The Orbit and Radiation Environment of the Young M Dwarf-Hosted Planet K2-25b
E. Gaidos, T. Hirano, D. J. Wilson +20
M dwarf stars are high-priority targets for searches for Earth-size and potentially Earth-like planets, but their planetary systems may form and evolve in very different circumstel…
Limits on the Spin-Orbit Angle and Atmospheric Escape for the 22 Myr-old Planet AU Mic b
Teruyuki Hirano, Vigneshwaran Krishnamurthy, Eric Gaidos +19
We obtained spectra of the pre-main sequence star AU Microscopii during a transit of its Neptune-sized planet to investigate its orbit and atmosphere. We used the high-dispersion n…
K2-280b -- a low density warm sub-Saturn around a mildly evolved star
Grzegorz Nowak, Enric Palle, Davide Gandolfi +57
We present an independent discovery and detailed characterisation of K2-280b, a transiting low density warm sub-Saturn in a 19.9-day moderately eccentric orbit (e = 0.35_{-0.04}^{+…
Transmission spectroscopy and Rossiter-McLaughlin measurements of the young Neptune orbiting AU Mic
E. Palle, M Oshagh, N. Casasayas-Barris +8
AU Mic~b is a Neptune size planet on a 8.47-day orbit around the nearest pre-main sequence (20 Myr) star to the Sun, the bright (V=8.81) M dwarf AU Mic. The planet was prelim…