Masato Ishizuka
A5086578003- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Spectroscopy and Laser Applications
- Advanced Fiber Laser Technologies
- Adaptive optics and wavefront sensing
- Advanced Fiber Optic Sensors
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
- Geomagnetism and Paleomagnetism Studies
- Astronomical Observations and Instrumentation
- History and Developments in Astronomy
- Astronomical and nuclear sciences
- Space Exploration and Technology
- Geophysics and Gravity Measurements
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- High-pressure geophysics and materials
The University of Tokyo
2016-2024
Hitachi (Japan)
2020
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...
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 obtained high-resolution infrared spectroscopy and short-cadence photometry of the 600-800 Myr Praesepe star K2-100 during transits its 1.67-day planet. This Neptune-size object, discovered by NASA K2 mission, is an interloper in "desert" planets with similar radii on short period orbits. Our observations can be used to understand origin evolution constraining orbital eccentricity transit fitting, measuring spin-orbit obliquity Rossiter-McLaughlin effect, detecting any extended, escaping...
Abstract We present a near-infrared direct imaging search for accretion signatures of possible protoplanets around the young stellar object (YSO) TW Hya, multi-ring disk exhibiting evidence planet formation. The Pa β line (1.282 μ m) is an indication onto protoplanet, and its intensity much higher than that blackbody radiation from protoplanet. focused on performed Keck/OSIRIS spectroscopic observations. Although spectral differential (SDI) reduction detected no signatures, results study...
Studies of planetary systems stars in star-forming regions and young clusters open a window on the formative stages evolution. We obtained high-cadence high-resolution infrared spectroscopy solar-mass Taurus association-member V1298 Tau during transit its 10R$_{\oplus}$-size "b" planet. measured systemic radial velocity find that kinematics suggest an affiliation with $\gtrsim$6 Myr-old subgroup. A comparison nearby, co-moving star 2M0405 stellar evolution models suggests age $\sim$10-25...
M dwarf stars are high-priority targets for searches Earth-size and potentially Earth-like planets, but their planetary systems may form evolve in very different circumstellar environments than those of solar-type stars. To explore the evolution these systems, we obtained transit spectroscopy photometry Neptune-size planet orbiting ~650 Myr-old Hyades K2-25. An analysis variation spectral line shape induced by Doppler "shadow" indicate that planet's orbit is closely aligned with stellar...
Abstract We report the near-infrared radial velocity (RV) discovery of a super-Earth planet on 10.77 d orbit around M4.5 dwarf Ross 508 (Jmag = 9.1). Using precision RVs from Subaru Telescope IRD (InfraRed Doppler) instrument, we derive semi-amplitude $3.92^{+0.60}_{-0.58}\:\mbox{m}\:{\mbox{s}^{-1}}$, corresponding to with minimum mass $m \sin i 4.00^{+0.53}_{-0.55}\, M_{\oplus }$. find no evidence significant signals at detected period in spectroscopic stellar activity indicators or MEarth...
Abstract In an effort to measure the Rossiter–McLaughlin effect for TRAPPIST-1 system, we performed high-resolution spectroscopy during transits of planets e, f, and b. The spectra were obtained with InfraRed Doppler spectrograph on Subaru 8.2 m telescope, supplemented simultaneous photometry a 1 telescope Las Cumbres Observatory Global Telescope. By analyzing anomalous radial velocities, found projected stellar obliquity be λ = ± 28° under assumption that three have coplanar orbits,...
We will present a new instrument, REACH (Rigorous Exoplanetary Atmosphere Characterization with High dispersion coronography) to realize very high spectral resolution, over R=100,000 at extreme contrast by combining the high-resolution spectrograph InfraRed Doppler (IRD) and adaptive optics SCExAO Subaru Telescope. consists of mini-IFU like 7 single-mode fiber bundle located focus SCExAO, high-speed photometric monitoring camera, beam switching feed system from IRD's 2 fibers. provide an...
Recent progress in high-dispersion spectroscopy has revealed the presence of vaporized heavy metals and ions atmosphere hot Jupiters whose dayside temperature is larger than 2000 K, categorized as ultra (UHJs). Using archival data high resolution transmission obtained with Subaru telescope, we searched for neutral HD149026b, a Jupiter cooler UHJs. By removing stellar telluric absorption using cross-correlation technique, report tentative detection titanium 4.4 sigma marginal signal iron 2.8...
The InfraRed Doppler (IRD) instrument is a high-dispersion spectrograph that available on Subaru Telescope to explore extrasolar planets via infrared radial velocity (RV) observations. Subaru/IRD especially useful in the search of low-mass planet around cool M-type dwarfs for which RV observations are essential. We report our early performance tests IRD. IRD's two H2RG detectors have been evaluated with detector readout technique, ensuring their noise made sufficiently smaller than stellar...
Abstract Sub-Neptunes with radii of 2–3 R ⊕ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties bulk compositions transiting sub-Neptunes provide clues to the formation evolution close-in small In this paper, we present discovery follow-up four orbiting M dwarfs (TOI-782, TOI-1448, TOI-2120, TOI-2406), three which were newly validated by ground-based observations statistical analyses. TOI-782 b, TOI-1448 TOI-2120 TOI-2406 b have <mml:math...
Precision radial velocity (RV) measurements in the near-infrared are a powerful tool to detect and characterize exoplanets around low-mass stars or young with higher magnetic activity. However, presence of strong telluric absorption lines emission near infrared that significantly vary time can prevent extraction RV information from these spectra by classical techniques, which ignore mask lines. We present methodology pipeline derive precision RVs using forward-modeling technique. applied...
The Subaru telescope is currently performing a strategic program (SSP) using the high-precision near-infrared (NIR) spectrometer IRD to search for exoplanets around nearby mid/late-M~dwarfs via radial velocity (RV) monitoring. As part of observing strategy exoplanet survey, signatures massive companions such as RV trends are used reduce priority those stars. However, this information remains useful studying stellar multiplicity M~dwarfs. To ``deprioritized" M~dwarfs, we observed 14 IRD-SSP...
We report the results of fiber mode scrambler experiments for Infra-Red Doppler instrument (IRD) on Subaru 8.2-m telescope. IRD is a fiber-fed, high precision radial velocity (RV) to search exoplanets around nearby M dwarfs at near-infrared wavelengths. It high-resolution spectrograph with an Echelle grating. The expected RV measurement ∼1 m s−1 state art laser frequency comb wavelength calibration. In observations, one most significant instrumental noise change intensity distribution...
Abstract We report the first detection of a hydroxyl radical (OH) emission signature in planetary atmosphere outside solar system, this case, dayside WASP-33b. analyze high-resolution near-infrared spectra WASP-33b taken using InfraRed Doppler spectrograph on 8.2 m Subaru telescope. The telluric and stellar lines are removed detrending algorithm, SysRem . residuals then cross-correlated with OH H 2 O spectrum templates produced several different line lists. check confirm accuracy lists by...
Abstract Silicon and strontium are key elements to explore the nucleosynthesis chemical evolution of Galaxy by measurements very metal-poor stars. There are, however, only a few useful spectral lines these in optical range that measurable for such low-metallicity Here we report on abundances two determined from near-infrared high-resolution spectra obtained with Subaru Telescope Infrared Doppler instrument. Si as many 26 six extremely stars (−4.0 &lt; [Fe/H] −1.5), which significantly...
We report the results of fiber mode scrambler experiments for Infra-Red Doppler instrument (IRD) on Subaru 8.2-m telescope. IRD is a near infrared, high-precision radial velocity (RV) to search exoplanets around M dwarfs. It fiber-fed, high-resolution (R~70000) spectrograph with an Echelle grating and state-of-the art laser frequency comb. Expected precision RV measurements 1m/s. To achieve 1m/s accuracy, we must reduce modal noise, which intensity instability light at end multimode fibers....
Sub-Neptunes with $2-3R_\oplus$ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties bulk compositions of transiting sub-Neptunes provide clues to the formation evolution close-in small In this paper, we present discovery follow-up four orbiting M dwarfs (TOI-782, TOI-1448, TOI-2120, TOI-2406), three which were newly validated by ground-based observations statistical analyses. TOI-782 b, TOI-1448 TOI-2120 TOI-2406 b have radii $R_\mathrm{p} =...
Orbital parameters of stellar companions can be constrained by multi-epoch observations where the astrometric position relative to host star is measured. Additionally, radial velocity (RV) measurements may constrain companion mass. We describe two major advances for high contrast imaging systems that significantly improve estimation orbital and masses. First, well-calibrated fiducial satellite speckles are inserted in science images way deformable mirror (DM) modulation measurement accuracy....