A5084867445- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Spectroscopy and Laser Applications
- Atmospheric Ozone and Climate
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Photonic and Optical Devices
- Glass properties and applications
- Astrophysical Phenomena and Observations
- Solid State Laser Technologies
- Galaxies: Formation, Evolution, Phenomena
- Isotope Analysis in Ecology
- Optical Coatings and Gratings
- Luminescence Properties of Advanced Materials
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- Advanced Fiber Laser Technologies
- Gamma-ray bursts and supernovae
- Astronomical and nuclear sciences
- Optical Coherence Tomography Applications
- Thin-Film Transistor Technologies
- Photonic Crystal and Fiber Optics
- Statistical and numerical algorithms
Shiga University of Medical Science
2022-2024
Kyoto Sangyo University
2015-2024
The University of Tokyo
2011-2016
National Astronomical Observatory of Japan
2011
Kyushu University
2000-2002
We present new, wide and deep images in the 1.1 mm continuum $^{12}$CO ($J$=1-0) emission toward northern part of Orion A Giant Molecular Cloud (Orion-A GMC). The data were taken with AzTEC camera mounted on Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope Chile, 25 beam receiver (BEARS) NRO 45 On-The-Fly (OTF) mode. observations are widest $(\timeform{1.D7}$ $\times$ $\timeform{2.D3}$, corresponding to 12 pc 17 pc) highest-sensitivity ($\sim$9 mJy beam$^{-1}$) dust-continuum...
Context . Given their high luminosities ( L ≳ 10 4 ⊙ ), red supergiants (RSGs) are good tracers of the chemical abundances young stellar population in Milky Way and nearby galaxies. However, previous abundance analyses tailored to RSGs suffer some systematic uncertainties originating in, most notably, synthesized molecular spectral lines for RSGs. Aims We establish a new analysis procedure that circumvents difficulties faced works, test with ten observed near-infrared high-resolution...
Classical Cepheids are useful tracers of the Galactic young stellar population because their distances and ages can be determined from period-luminosity period-age relations. In addition, radial velocities chemical abundance derived spectroscopic observations, providing further insights into structure evolution Galaxy. Here, we report classical near Center, three which were reported in 2011, other for first time. The these suggest that stars orbit within Nuclear Stellar Disk, a group...
We present a comprehensive survey of diffuse interstellar bands (DIBs) in $0.91-1.32\mu$m with newly-developed near-infrared (NIR) spectrograph, WINERED, mounted on the Araki 1.3 m Telescope Japan. obtained high-resolution ($R=28,300$) spectra 25 early-type stars color excesses $0.07<E(B-V)<3.4$. In addition to five DIBs previously detected this wavelength range, we identified 15 new DIBs, 7 which were reported as DIB "candidates" by Cox. analyze correlations among NIR strong optical and...
We obtained the near-infrared (NIR) high-resolution ($R\equiv\lambda/\Delta\lambda\sim20,000$) spectra of seven brightest early-type stars in Cygnus OB2 association for investigating environmental dependence diffuse interstellar bands (DIBs). The WINERED spectrograph mounted on Araki 1.3m telescope Japan was used to collect data. All 20 known DIBs within wavelength coverage ($0.91<\lambda<1.36\mu$m) were clearly detected along all lines sight because their high flux density NIR range and...
Near-infrared (NIR) high-resolution spectroscopy is a fundamental observational method in astronomy. It provides significant information on the kinematics, magnetic fields, and chemical abundances, of astronomical objects embedded or behind highly extinctive clouds at cosmological distances. Scientific requirements have accelerated development technology required for NIR high resolution spectrographs using 10 m telescopes. WINERED near-infrared spectrograph that currently mounted 1.3 Araki...
Abstract WINERED is a novel near-infrared (NIR) high-resolution spectrograph (HRS) that pursues the highest possible sensitivity to realize high-precision spectroscopy in NIR as optical wavelength range. covers 0.9–1.35 μ m ( z , Y and J -bands) with three modes (Wide mode two Hires modes) at maximum spectral resolutions of R = 28,000 70,000. For fulfilling objective, designed an unprecedentedly high instrument throughput (up 50% including quantum efficiency array) times or more than other...
Abstract We present a data reduction pipeline written in Python for obtained with the near-infrared cross-dispersed echelle spectrograph, WINERED, which yields 0.91–1.35 μ m spectrum resolving power of <?CDATA ${R}_{\max }\equiv \lambda /{\rm{\Delta }}\lambda ={\rm{28,000}}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>R</mml:mi> </mml:mrow> <mml:mi>max</mml:mi> </mml:msub> <mml:mo>≡</mml:mo> <mml:mi>λ</mml:mi> <mml:mo...
The fluorescence characteristics of different Ce3+:Er3+-codoped fluoride host glasses, such as fluorozirconate and fluoroindate glass, are reported. It is shown that Ce3+ codoping into Er3+ doped glasses resulted in a quenching ions from the I11/24 to I13/24 state, branching ratio for I11/24→I13/24 transition increased 0.20 over 0.80 by 2.0 mol % Ce3+. Further, quantum yield at 1.55 μm was also significantly improved. A fiber laser operating band with 980 nm excitation has been realized...
The stellar effective temperature is the fundamental parameter of atmospheres. It characterizes spectra and plays an essential role in chemical abundance analysis. Previous optical studies have shown that line-depth ratios (LDRs) are good indicators temperature. Essentially, absorption lines with different excitation potentials can be used as scales. most important advantage LDRs their robustness against interstellar reddening extinction. Furthermore, scales constructed calibrated...
We report a method of correcting near-infrared (0.90-1.35 $\mu$m) high-resolution ($\lambda/\Delta\lambda\sim28,000$) spectrum for telluric absorption using the corresponding standard star. The proposed uses an A0\,V star or its analog as from which on order 100 intrinsic stellar lines are carefully removed with help reference synthetic spectrum. find that this can also be applied to feature-rich objects having spectra heavily blended and present application G-type giant approach. develop...
For a detailed analysis of stellar chemical abundances, high-resolution spectra in the optical have mainly been used, while development near-infrared (NIR) spectrograph has opened new wavelength windows. Red giants large number resolved absorption lines both and NIR wavelengths, but characteristics different wave passbands are not necessarily same. We present selection FeI $z^{\prime}$, $Y$, $J$ bands (0.91-1.33 $\mu$m). On basis two lists this range, Vienna Atomic Line Database (VALD)...
ABSTRACT Determining the effective temperatures (Teff) of red supergiants (RSGs) observationally is important in many fields stellar physics and galactic astronomy, yet some significant difficulties remain as a result model uncertainty, which originates mainly extended atmospheres RSGs. Here we propose line-depth ratio (LDR) method use only Fe i lines. As opposed to conventional LDR method, lines multiple species are involved, this insensitive surface gravity effects expected circumvent...
The effective temperature, one of the most fundamental atmospheric parameters a star, can be estimated using various methods, and here we focus on method line-depth ratios (LDRs). This combines low- high-excitation lines makes use relations between LDRs these line pairs temperature. It has an advantage, for example, being minimally affected by interstellar reddening, which changes stellar colours. We report 81 temperature established with high-resolution, $λ/Δλ\sim 28,000$, spectra nine G-...
We searched for diffuse interstellar bands (DIBs) in the 0.91$<\lambda<$1.33 $\mu$m region by analyzing near-infrared (NIR) high-resolution ($R=20,000$ and 28,000) spectra of 31 reddened early-type stars ($0.04<E(B-V)<4.58$) an unreddened reference star. The were collected using WINERED spectrograph, which was mounted on 1.3 m Araki telescope at Koyama Astronomical Observatory, Japan, 2012--2016, 3.58 New Technology Telescope La Silla Chile, 2017--2018. detected 54 DIBs -- 25 are newly this...
Abstract Stellar absorption lines of heavy elements can give us various insights into the chemical evolution our Galaxy and other nearby galaxies. Recently developed spectrographs for near-infrared wavelengths are becoming more powerful at producing a large number high-quality spectra, but identification characterization in infrared range remain to be fulfilled. We searched heavier than iron group, i.e., those Ni, Y (9760–11100 Å) J (11600–13200 bands. considered three catalogs, Vienna...
To investigate the chemical abundance of broad-line region clouds in quasars at high redshifts, we performed near-infrared spectroscopy six luminous z ~ 2.7 with WINERED spectrograph mounted on New Technology Telescope (NTT) La Silla Observatory, Chile. The measured Fe II/Mg II flux ratios nearly matched published data for 0.7 < 1.6, suggesting that there is no evolution over a long period cosmic time, which consistent previous studies. derive abundances from equivalent widths (EWs), their...
Red giants show a large number of absorption lines in both optical and near-infrared wavelengths. Still, the characteristics different wave passbands are not necessarily same. We searched for Mg I, Si Ca Ti Cr Ni I z', Y, J bands (0.91-1.33 $\mu$m), that useful precise abundance analyses, from two compilations lines, namely, third release Vienna Atomic Line Database (VALD3) catalog published by Melendez & Barbuy 1999 (MB99). selected sufficiently strong severely blended ended up with 191...
ABSTRACT Newly-developed spectrographs with increased resolving powers, particularly those covering the near-IR range, allow characterization of more and absorption lines in stellar spectra. This includes identification confirmation calibration oscillator strengths. In this study, we provide empirical values ${{\rm log} gf}$ based on abundances classical Cepheids obtained optical spectra to establish consistency between infrared abundance results. Using time series WINERED spectrograph...
Ratios of carefully selected line depths are sensitive to stellar effective temperature ($T_\mathrm{eff}$). Relations established between line-depth ratio (LDR) and $T_\mathrm{eff}$ allow one determine precisely. However, LDRs can also depend on metallicity abundance ratios, which limit the accuracy LDR method unless such effects properly taken into account. We investigate effect using $H$-band spectra parameters published by APOGEE project. clearly detected ratios; derived from a given...
We present the first spectroscopic abundance determination of iron, alpha-elements (Si, Ca and Ti) sodium for Mira variable V1 in metal-rich globular cluster NGC 5927. use high-resolution (R~ 28,000), high signal-to-noise ratio (~200) spectra collected with WINERED, a near-infrared (NIR) spectrograph covering simultaneously wavelength range 0.91--1.35 micron. The effective temperature surface gravity at pulsation phase observation were estimated using both optical (V) NIR time-series...
The characteristics of the inner Galaxy remain obscured by significant dust extinction, and hence infrared surveys are useful to find young Cepheids whose distances ages can be accurately determined. A near-infrared photometric spectroscopic survey was carried out three classical were unveiled in disk, around 20 30 degrees Galactic longitude. targets feature small Galactocentric distances, 3-5 kpc, their velocities important as they may under environmental influence bar. While one has radial...
WINERED is a PI-type 0.9 – 1.35 μm high-resolution spectrograph developed by the Laboratory of Infrared highresolution Spectrograph (LiH) Koyama Astronomical Observatory at Kyoto Sangyo University, Japan. The scope to realize near-infrared (NIR) with both wide coverage and high sensitivity. provides three observational modes called as Wide, Hires-Y Hires-J modes. Wide mode simultaneously covers z, Y J-bands in single exposure R ≡ λ/Δλ = 28,000 was commissioned for 1.3...
A line-depth ratio (LDR) of two spectral lines with different excitation potentials is expected to be correlated the effective temperature ($T_\mathrm{eff}$). It possible determine $T_\mathrm{eff}$ a star precision tens Kelvin if dozens or hundreds tight LDR-$T_\mathrm{eff}$ relations can used. Most previous studies on LDR method were limited optical wavelengths, but Taniguchi and collaborators reported 81 in $YJ$ band, 0.97-1.32 $\mu\mathrm{m}$, 2018. However, their sample only 10 giants,...
We report the first detection of C$_2$ $A^1\Pi_u$--$X^1\Sigma_g^+$ (0,0) and CN $A^2\Pi_u$--$X^2\Sigma^+$ absorption bands in interstellar medium. The was made using near-infrared (0.91--1.35 $\mu$m) high-resolution ($R=20,000$ 68,000) spectra Cygnus OB2 No.\,12 collected with WINERED spectrograph mounted on 1.3 m Araki telescope. $A$--$X$ (1,0) were detected simultaneously. These have larger oscillator strengths, compared (2,0) optical. In spectrum band $R=68,000$, three velocity components...