Teruyuki Hirano
A5053280583- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- History and Developments in Astronomy
- High-pressure geophysics and materials
- Spectroscopy and Laser Applications
- Atmospheric Ozone and Climate
- Calibration and Measurement Techniques
- Astrophysical Phenomena and Observations
- Solar and Space Plasma Dynamics
- Scientific Research and Discoveries
- Space Exploration and Technology
- Geophysics and Gravity Measurements
- Astronomical and nuclear sciences
- Spacecraft and Cryogenic Technologies
- Planetary Science and Exploration
- Geomagnetism and Paleomagnetism Studies
- Adaptive optics and wavefront sensing
- Pulsars and Gravitational Waves Research
- Spacecraft Design and Technology
- Ionosphere and magnetosphere dynamics
- Crystal Structures and Properties
National Astronomical Observatory of Japan
2021-2025
Astrobiology Center
2020-2025
The Graduate University for Advanced Studies, SOKENDAI
2021-2025
EarthTech International (United States)
2025
The University of Tokyo
2009-2024
Tokyo Metropolitan Komaba High School
2024
American Institute of Aeronautics and Astronautics
2024
Tokyo Institute of Technology
1990-2021
National Institutes of Natural Sciences
2020
University of Hawaii System
2006-2019
We provide evidence that the obliquities of stars with close-in giant planets were initially nearly random, and low are often observed a consequence star–planet tidal interactions. The is based on 14 new measurements Rossiter–McLaughlin effect (for systems HAT-P-6, HAT-P-7, HAT-P-16, HAT-P-24, HAT-P-32, HAT-P-34, WASP-12, WASP-16, WASP-18, WASP-19, WASP-26, WASP-31, Gl 436, Kepler-8), as well critical review previous observations. low-obliquity (well-aligned) those for which expected...
We report high-resolution spectroscopic detection of TiO molecular signature in the day-side spectra WASP-33 b, second hottest known hot Jupiter. used High-Dispersion Spectrograph (HDS; R $\sim$ 165,000) wavelength range 0.62 -- 0.88 $\mu$m with Subaru telescope to obtain b. suppress and correct systematic effects instrument, telluric stellar lines by using SYSREM algorithm after selection good orders based on Barnard star other M-type stars. detect a 4.8-$\sigma$ signal at an orbital...
Abstract The observation of the kilonova AT2017gfo and investigations its light curves spectra confirmed that neutron star mergers are sites r -process nucleosynthesis. However, identification elements responsible for spectral features is still challenging, particularly at near-infrared wavelengths. In this study, we systematically searched all possible transitions heavy using experimentally calibrated energy levels. Our analysis reveals most candidate with strong absorption lines...
Abstract We present the first evidence of a retrograde orbit transiting exoplanet HAT-P-7b. The discovery is based on measurement Rossiter–McLaughlin effect with Subaru HDS during transit HAT-P-7b, which occurred 2008 May 30 UT. Our best-fit model shows that spin–orbit alignment angle this planet $\lambda$$=$$-132.^\circ 6^{+\timeform{10.^\circ 5}}_{-\timeform{16.^\circ3}}$. existence such has been predicted by recent planetary migration models consider planet–planet scattering processes, or...
We present the discovery of a transiting exoplanet candidate in K2 Field-1 with an orbital period 9.1457 hr: K2-22b. The highly variable transit depths, ranging from $\sim$0\% to 1.3\%, are suggestive planet that is disintegrating via emission dusty effluents. characterize host star as M-dwarf $T_{\rm eff} \simeq 3800$ K. have obtained ground-based measurements several 1-m class telescopes and GTC. These observations (1) improve ephemeris; (2) confirm nature depths; (3) indicate variations...
The angle $\psi$ between a planet's orbital axis and the spin of its parent star is an important diagnostic planet formation, migration, tidal evolution. We seek empirical constraints on by measuring stellar inclination $i_{\rm s}$ via asteroseismology for ensemble 25 solar-type hosts observed with NASA's Kepler satellite. Our results are consistent alignment at 2-$\sigma$ level all stars in sample, meaning that system surrounding red-giant Kepler-56 remains as only unambiguous misaligned...
We present the discovery of TOI-197.01, first transiting planet identified by Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology host star is possible. TOI-197 (HIP116158) a bright (V=8.2 mag), spectroscopically classified subgiant oscillates with an average frequency about 430 muHz and displays clear signature mixed modes. The oscillation amplitude confirms that redder TESS bandpass compared to Kepler has small effect on oscillations, supporting expected yield thousands...
We report on precise Doppler measurements of L231-32 (TOI-270), a nearby M dwarf ($d=22$ pc, $M_\star = 0.39$ M$_\odot$, $R_\star 0.38$ R$_\odot$), which hosts three transiting planets that were recently discovered using data from the Transiting Exoplanet Survey Satellite (TESS). The are 1.2, 2.4, and 2.1 times size Earth have orbital periods 3.4, 5.7, 11.4 days. obtained 29 high-resolution optical spectra with newly commissioned Echelle Spectrograph for Rocky Stable Spectroscopic...
Abstract The warm Neptune GJ 3470b transits a nearby ( d = 29 pc) bright slowly rotating M1.5-dwarf star. Using spectroscopic observations during two with the newly commissioned NEID spectrometer on WIYN 3.5 m Telescope at Kitt Peak Observatory, we model classical Rossiter–McLaughlin effect, yielding sky-projected obliquity of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>λ</mml:mi> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>98</mml:mn>...
Context. In the age of JWST, temperate terrestrial exoplanets transiting nearby late-type M dwarfs provide unique opportunities for characterising their atmospheres, as well searching biosignature gases. this context, benchmark TRAPPIST-1 planetary system has garnered interest a broad scientific community. Aims. We report here discovery and validation two super-Earths LP 890-9 (TOI-4306, SPECULOOS-2), relatively low-activity (32 pc) M6V star. The inner planet, b, was first detected by TESS...
We present the discovery and characterisation of two transiting planets observed by \textit{TESS} in light curves young bright (V=9.67) star HD73583 (TOI-560). perform an intensive spectroscopic photometric space- ground-based follow-up order to confirm characterise system. found that is a ($\sim 500$~Myr) active with rotational period $12.08 \pm 0.11 $\,d, mass radius $ 0.73 0.02 M_\odot$ $0.65 R_\odot$, respectively. b ($P_b=6.3980420 _{ - 0.0000062 }^{+0.0000067}$ d) has $10.2...
Mass, radius, and age measurements of young (<100 Myr) planets have the power to shape our understanding planet formation. However, stars tend be extremely variable in both photometry radial velocity, which makes constraining these properties challenging. The V1298 Tau system four ~0.5 Rjup transiting a pre-main sequence star presents an important, if stress-inducing, opportunity directly observe measure infant planets. Su\'arez-Mascare\~no et al. (2021) published radial-velocity-derived...
We obtain analytical expressions for the velocity anomaly due to Rossiter- McLaughlin effect, case when anomalous radial is obtained by cross-correlation with a stellar template spectrum. In limit of vanishing width absorption lines, our result reduces formula derived Ohta et al. (2005), which based on first moment distorted lines. Our new contains term dependent linewidth, becomes important rotational line broadening appreciable. generate mock transit spectra four existing exoplanetary...
We present an investigation of spin-orbit angles for planetary system candidates reported by Kepler. By combining the rotational period $P_s$ inferred from flux variation due to starspots and projected velocity $V\sin I_s$ stellar radius obtained a high resolution spectroscopy, we attempt estimate inclination $I_s$ spin axis with respect line-of-sight. For transiting systems, in which orbits are edge-on seen us, can be useful indicator alignment/misalignment. newly conducted spectroscopic...
We present an improved formula for the anomalous radial velocity of star during planetary transits due to Rossiter-McLaughlin (RM) effect. The improvement comes from a more realistic description stellar absorption line profiles, taking into account rotation, macroturbulence, thermal broadening, pressure and instrumental broadening. Although is derived case in which velocities are measured by cross-correlation, we show through numerical simulations that accurately describes cases where with...
HD3167 is a bright (V=8.9 mag) K0V star observed by the NASA's K2 space mission during its Campaign 8. It has been recently found to host two small transiting planets, namely, HD3167b, an ultra short period (0.96 d) super-Earth, and HD3167c, mini-Neptune on relatively long-period orbit (29.85 d). Here we present intensive radial velocity follow-up of performed with FIES@NOT, HARPS@ESO-3.6m, HARPS-N@TNG spectrographs. We revise system parameters determine radii, masses, densities planets...
IRD is the near-infrared high-precision radial velocity instrument for Subaru 8.2-m telescope. It a relatively compact (~1m size) spectrometer with new echelle-grating and Volume-Phase Holographic gratings covering 1-2 micron wavelengths combined an original frequency comb using optical pulse synthesizer. The will employ 4096x4096-pixel HgCdTe array under testing at IfA, University of Hawaii. Both telescope/Adaptive Optics beams are fed to via fibers, while placed Nasmyth platform Expected...
We present a test for spin-orbit alignment the host stars of 25 candidate planetary systems detected by {\it Kepler} spacecraft. The inclination angle each star's rotation axis was estimated from its period, rotational line broadening, and radius. periods were determined using photometric time series. broadening high-resolution optical spectra with Subaru/HDS. Those same used to determine photospheric parameters (effective temperature, surface gravity, metallicity) which then interpreted...
The KOI-94 system is a closely packed, multi-transiting planetary discovered by the Kepler space telescope. It known as first that exhibited rare event called "planet–planet eclipse (PPE)," in which two planets partially overlap with each other their double-transit phase. In this paper, we constrain parameters of an analysis transit timing variations (TTVs). Such constraints are independent radial velocity (RV) recently performed Weiss and coworkers, valuable examining reliability parameter...
The Infrared Doppler (IRD) instrument is a fiber-fed high-resolution NIR spectrometer for the Subaru telescope covering Y,J,H-bands simultaneously with maximum spectral resolution of 70,000. main purpose IRD search Earth-mass planets around nearby M-dwarfs by precise radial velocity measurements, as well spectroscopic characterization exoplanet atmospheres. We report current status instrument, which undergoing commissioning at Telescope, and first light observation successfully done in...
Planets in the mass range from 2 to 15 MEarth are very diverse. Some of them have low densities, while others dense. By measuring masses and radii, mean structure, composition planets constrained. These parameters also give us important information about their formation evolution, possible processes for atmospheric loss.We determined masses, densities two transiting orbiting K2-106. The inner planet has an ultra-short period 0.57 days. outer is 13.3 days.Although similar different. For...
We obtained spectra of the pre-main sequence star AU Microscopii during a transit its Neptune-sized planet to investigate orbit and atmosphere. used high-dispersion near-infrared spectrograph IRD on Subaru telescope detect Doppler "shadow" from constrain projected stellar obliquity. Modeling observed planetary shadow suggests spin-orbit alignment system ($\lambda=-4.7_{-6.4}^{+6.8}$ degrees), but additional observations are needed confirm this finding. use both data with NIRSPEC Keck-II...
We validate a $R_p=2.32\pm 0.24R_\oplus$ planet on close-in orbit ($P=2.260455\pm 0.000041$ days) around K2-28 (EPIC 206318379), metal-rich M4-type dwarf in the Campaign 3 field of K2 mission. Our follow-up observations included multi-band transit from optical to near infrared, low-resolution spectroscopy, and high-resolution adaptive-optics (AO) imaging. perform global fit all observed transits using Gaussian process-based method show that depths passbands adopted for ground-based...
We present 44 validated planets from the 10$^\mathrm{th}$ observing campaign of NASA $K2$ mission, as well high resolution spectroscopy and speckle imaging follow-up observations. These come an initial set 72 vetted candidates, which we subjected to a validation process incorporating pixel-level analyses, light curve observational constraints, statistical false positive probabilities. Our planet sample has median values $R_p$ = 2.2 $R_\oplus$, $P_\mathrm{orb}$ 6.9 days, $T_{\mathrm{eq}}$ 890...
We present the discovery and characterisation of two transiting planets observed by Transiting Exoplanet Survey Satellite (TESS) orbiting nearby (d ~ 22 pc), bright (J 9 mag) M3.5 dwarf LTT 3780 (TOI-732). confirm both their association with via ground-based photometry determine masses using precise radial velocities measured CARMENES spectrograph. Precise stellar parameters determined from high resolution spectra that is a mid-M an effective temperature T_eff = 3360 +\- 51 K, surface...