Abstract
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 ...near-infrared spectrograph InfraRed Doppler (IRD) on the Subaru telescope to detect the Doppler “shadow” from the planet and constrain the projected stellar obliquity. Modeling of the observed planetary Doppler shadow suggests a spin–orbit alignment of the system (
deg), but additional observations are needed to confirm this finding. We use both the IRD data and spectra obtained with NIRSPEC on Keck II to search for absorption in the 1083 nm line of metastable triplet He
i
by the planet’s atmosphere and place an upper limit for the equivalent width of 3.7 mÅ at 99% confidence. With this limit and a Parker wind model we constrain the escape rate from the atmosphere to
M
⊕
Gyr
−1
, comparable to the rates predicted by an X-ray and ultraviolet energy-limited escape calculation and hydrodynamic models, but refinement of the planet mass is needed for rigorous tests.
This paper presents an improved method for our recently proposed dynamic displacement measurement based on triangle phase modulation. The use of deep phase modulation eliminates the need for ...preliminary measurement of half-wave voltage Vπ for the phase modulator. We demonstrate displacement measurement with tens-of-nanometer scale taking place within a few micro seconds, where the temporal resolution is 33 ns. A long-term stability is also realized by employing a simple feedback control for the interferometer. The measurement precision is proved to be as high as that in the previously developed system that required careful preliminary measurement of Vπ.
Abstract
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 dayside of WASP-33b. We analyze ...high-resolution near-infrared emission spectra of WASP-33b taken using the InfraRed Doppler spectrograph on the 8.2 m Subaru telescope. The telluric and stellar lines are removed using a detrending algorithm,
SysRem
. The residuals are then cross-correlated with OH and H
2
O planetary spectrum templates produced using several different line lists. We check and confirm the accuracy of OH line lists by cross-correlating with the spectrum of GJ 436. As a result, we detect the emission signature of OH at
K
p
of
km s
−1
and
v
sys
of −0.3
km s
−1
with a signal-to-noise ratio (S/N) of 5.4 and a significance of 5.5
σ
. Additionally, we marginally detect H
2
O emission in the
H
-band with an S/N of 4.0 and a significance of 5.2
σ
using the POKAZATEL line list. However, no significant signal is detected using the HITEMP 2010, which might be due to differences in line positions and strengths, as well as the incompleteness of the line lists. Nonetheless, this marginal detection is consistent with the prediction that H
2
O is mostly thermally dissociated in the upper atmosphere of the ultra-hot Jupiters. Therefore, along with CO, OH is expected to be one of the most abundant O-bearing molecules in the dayside atmosphere of ultra-hot Jupiters and should be considered when studying their atmospheres.
In an effort to measure the Rossiter-McLaughlin effect for the TRAPPIST-1 system, we performed high-resolution spectroscopy during transits of planets e, f, and b. The spectra were obtained with the ...InfraRed Doppler spectrograph on the Subaru 8.2 m telescope, and were supplemented with simultaneous photometry obtained with a 1 m telescope of the Las Cumbres Observatory Global Telescope. By analyzing the anomalous radial velocities, we found the projected stellar obliquity to be λ = 1 28° under the assumption that the three planets have coplanar orbits, although we caution that the radial-velocity data show correlated noise of unknown origin. We also sought evidence for the expected deformations of the stellar absorption lines, and thereby detected the "Doppler shadow" of planet b with a false-alarm probability of 1.7%. The joint analysis of the observed residual cross-correlation map including the three transits gave °. These results indicate that the the TRAPPIST-1 star is not strongly misaligned with the common orbital plane of the planets, although further observations are encouraged to verify this conclusion.
Abstract
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 activity. ...However, the presence of strong telluric absorption lines and emission lines in the near-infrared that significantly vary in time can prevent extraction of RV information from these spectra by classical techniques, which ignore or mask the telluric lines. We present a methodology and pipeline to derive precision RVs from near-infrared spectra using a forward-modeling technique. We applied this to spectra with a wide wavelength coverage (Y, J, and H bands, simultaneously), taken by the InfraRed Doppler (IRD) spectrograph on the Subaru 8.2 m telescope. Our pipeline extracts the instantaneous instrumental profile of the spectrograph for each spectral segment, based on a reference spectrum of the laser-frequency comb that is injected into the spectrograph simultaneously with the stellar light. These profiles are used to derive the intrinsic stellar template spectrum, which is free from instrumental broadening and telluric features, as well as model and fit individual observed spectra in the RV analysis. Implementing a series of numerical simulations using theoretical spectra that mimic IRD data, we test the pipeline and show that IRD can achieve <2 m s−1 precision for slowly rotating mid-to-late M dwarfs with a signal-to-noise ratio ≳100 per pixel at 1000 nm. Dependences of RV precision on various stellar parameters (e.g., Teff, vsin i, Fe/H) and the impact of telluric-line blendings on the RV accuracy are discussed through the mock spectra analyses. We also apply the RV-analysis pipeline to the observed spectra of GJ 699 and TRAPPIST-1, demonstrating that the spectrograph and the pipeline are capable of an RV accuracy of <3 m s−1 at least on a time-scale of a few months.
Abstract
We obtained high-resolution spectra of the ultracool M-dwarf TRAPPIST-1 during the transit of its planet “b” using two high-dispersion near-infrared spectrographs, the Infrared Doppler (IRD) ...instrument on the Subaru 8.2m telescope, and the Habitable Zone Planet Finder (HPF) instrument on the 10 m Hobby–Eberly Telescope. These spectroscopic observations are complemented by a photometric transit observation for planet “b” using the APO/ARCTIC, which assisted us in capturing the correct transit times for our transit spectroscopy. Using the data obtained by the new IRD and HPF observations, as well as the prior transit observations of planets “b,” “e” and “f” from IRD, we attempt to constrain the atmospheric escape of the planet using the He
i
triplet 10830 Å absorption line. We do not detect evidence for any primordial extended H-He atmospheres in all three planets. To limit any planet-related absorption, we place an upper limit on the equivalent widths of <7.754 mÅ for planet “b,” <10.458 mÅ for planet “e,” <4.143 mÅ for planet “f” at 95% confidence from the IRD data, and <3.467 mÅ for planet “b” at 95% confidence from HPF data. Using these limits along with a solar-like composition isothermal Parker wind model, we attempt to constrain the mass-loss rates for the three planets. For TRAPPIST-1b, our models exclude the highest possible energy-limited rate for a wind temperature <5000 K. This nondetection of extended atmospheres with low mean-molecular weights in all three planets aids in further constraining their atmospheric composition by steering the focus toward the search of high-molecular-weight species in their atmospheres.
Abstract
Detailed chemical analyses of M dwarfs are scarce but necessary to constrain the formation environment and internal structure of planets being found around them. We present elemental ...abundances of 13 M dwarfs (2900 <
T
eff
< 3500 K) observed in the Subaru/IRD planet search project. They are mid- to late-M dwarfs whose abundance of individual elements has not been well studied. We use the high-resolution (∼70,000) near-infrared (970–1750 nm) spectra to measure the abundances of Na, Mg, Si, K, Ca, Ti, V, Cr, Mn, Fe, and Sr by the line-by-line analysis based on model atmospheres, with typical errors ranging from 0.2 dex for Fe/H to 0.3–0.4 dex for other X/H. We measure radial velocities from the spectra and combine them with Gaia astrometry to calculate the Galactocentric space velocities
UVW
. The resulting Fe/H values agree with previous estimates based on medium-resolution
K
-band spectroscopy, showing a wide distribution of metallicity (−0.6 < Fe/H < +0.4). The abundance ratios of individual elements X/Fe are generally aligned with the solar values in all targets. While the X/Fe distributions are comparable to those of nearby FGK stars, most of which belong to the thin-disk population, the most metal-poor object, GJ 699, could be a thick-disk star. The
UVW
velocities also support this. The results raise the prospect that near-infrared spectra of M dwarfs obtained in the planet search projects can be used to grasp the trend of elemental abundances and the Galactic stellar population of nearby M dwarfs.
ABSTRACT
Kepler showed a paucity of planets with radii of 1.5–2 R⊕ around solar mass stars but this radius-gap has not been well studied for low-mass star planets. Energy-driven escape models like ...photoevaporation and core-powered mass-loss predict opposing transition regimes between rocky and non-rocky planets when compared to models depicting planets forming in gas-poor environments. Here, we present transit observations of three super-Earth sized planets in the radius-gap around low-mass stars using high-dispersion InfraRed Doppler spectrograph on the Subaru 8.2 m telescope. The planets GJ 9827 b and d orbit around a K6V star and TOI-1235 b orbits a M0.5 star. We limit any planet-related absorption in the 1083.3 nm lines of triplet He i by placing an upper-limit on the equivalent width of 14.71, 18.39, and 1.44 mÅ for GJ 9827 b (99 per cent confidence), GJ 9827 d (99 per cent confidence), and TOI-1235 b (95 per cent confidence), respectively. Using a Parker wind model, we cap the mass-loss at >0.25 M⊕ Gyr−1 and >0.2 M⊕ Gyr−1 for GJ 9827 b and d, respectively (99 per cent confidence), and >0.05 M⊕ Gyr−1 for TOI-1235 b (95 per cent confidence) for a representative wind temperature of 5000 K. Our observed results for the three planets are more consistent with the predictions from photoevaporation and/or core-powered mass-loss models than the gas-poor formation models. However, more planets in the radius-gap regime around the low-mass stars are needed to robustly predict the atmospheric evolution in planets around low-mass stars.
ABSTRACTTominaga, R, Ishii, Y, Ueda, T, and Kurokawa, T. The effects of running speed on ground reaction forces and lower limb kinematics during single-leg stop movement. J Strength Cond Res ...30(5)1224–1230, 2016—The purpose of this study was to investigate the effects of running speed on both ground reaction forces (GRFs) and lower limb kinematics during the deceleration phase of the single-leg stop movement. With 7 male university students participating in this study, each subject accelerated forwards at 3 approach speeds (2.50, 2.75, and 3.00 m·s), and stopped with the right leg landing on the force plate. Kinematic data were recorded from a lateral view using 1 high-speed camera. The result was that all subjects indicated the same stopping pattern, and 3 peaks of the resultant GRF were observed. The first peak (P1) appeared before full foot-ground contact, and the time to peak from initial foot contact to P1 was significantly shorter with increasing approach speeds (p ≤ 0.05). The second (P2) and third (P3) peaks were observed after full foot-ground contact, and the resultant GRF at P3 and the posterior GRF at P2 and P3 were significantly greater with increasing approach speeds (p ≤ 0.05). The hip flexion and the planter flexion angles at each peak were larger with increasing approach speeds (p ≤ 0.05). However, there was no significant difference in the vertical GRF, range of motion, and angular velocity of hip, knee, and ankle joints when comparing different approach speeds. This study suggests that to improve the stop movement strategy under faster approach speeds, it is important to increase the magnitude of posterior GRF and the hip and ankle flexion angles under increasing speeds.
Abstract
Individual vibrational band spectroscopy presents an opportunity to examine exoplanet atmospheres in detail, by distinguishing where the vibrational state populations of molecules differ ...from the current assumption of a Boltzmann distribution. Here, retrieving vibrational bands of OH in exoplanet atmospheres is explored using the hot Jupiter WASP-33b as an example. We simulate low-resolution spectroscopic data for observations with the JWST's NIRSpec instrument and use high-resolution observational data obtained from the Subaru InfraRed Doppler instrument (IRD). Vibrational band–specific OH cross-section sets are constructed and used in retrievals on the (simulated) low- and (real) high-resolution data. Low-resolution observations are simulated for two WASP-33b emission scenarios: under the assumption of local thermal equilibrium (LTE) and with a toy non-LTE model for vibrational excitation of selected bands. We show that mixing ratios for individual bands can be retrieved with sufficient precision to allow the vibrational population distributions of the forward models to be reconstructed. A fit for the Boltzmann distribution in the LTE case shows that the vibrational temperature is recoverable in this manner. For high-resolution, cross-correlation applications, we apply the individual vibrational band analysis to an IRD spectrum of WASP-33b, applying an “unpeeling” technique. Individual detection significances for the two strongest bands are shown to be in line with Boltzmann-distributed vibrational state populations, consistent with the effective temperature of the WASP-33b atmosphere reported previously. We show the viability of this approach for analyzing the individual vibrational state populations behind observed and simulated spectra, including reconstructing state population distributions.
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