A5039368018- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Isotope Analysis in Ecology
- Astrophysics and Star Formation Studies
- Atmospheric Ozone and Climate
- Planetary Science and Exploration
- Nuclear Physics and Applications
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Spacecraft and Cryogenic Technologies
- Space Exploration and Technology
- Spectroscopy and Laser Applications
- Mass Spectrometry Techniques and Applications
- Optical Coatings and Gratings
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Photonic and Optical Devices
- High-pressure geophysics and materials
- Solar and Space Plasma Dynamics
- Molecular Spectroscopy and Structure
- Pulsars and Gravitational Waves Research
- Atomic and Molecular Physics
- SAS software applications and methods
- Geomagnetism and Paleomagnetism Studies
Kyoto Sangyo University
2016-2025
National Astronomical Observatory of Japan
2023
Astronomical Observatory
2014-2017
The University of Tokyo
2005-2016
Institut d'Astrophysique de Paris
2011
European Southern Observatory
2011
Vrije Universiteit Brussel
2011
University of Hawaiʻi at Mānoa
2005
European Southern Observatory
2005
University of Maryland, College Park
2005
The identity of dark matter has been a mystery in astronomy, cosmology, and particle theory for about century. We present the first search with high-dispersion spectrograph by using WINERED at 6.5 m Magellan Clay telescope to measure photons from decays. dwarf spheroidal galaxies (dSphs) Leo V Tucana II are observed utilizing an object-sky-object nodding observation technique. Employing zero consistent flux data after sky subtraction performing Doppler shift analysis further background...
Photometric and spectroscopic data of the energetic Type Ic supernova (SN) 2002ap are presented, properties SN investigated through models its spectral evolution light curve. The is spectroscopically similar to "hypernova" 1997ef. However, kinetic energy [~(4-10) × 1051 ergs] mass ejected (2.5-5 M☉) smaller, resulting in a faster evolving synthesized ~0.07 M☉ 56Ni, peak luminosity was that normal SNe. Brightness alone should not be used define hypernova, whose defining character, namely very...
On 4 July 2005, many observatories around the world and in space observed collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there new material after impact compositionally different from seen before impact; (ii) ratio dust mass to gas ejecta much larger than (iii) activity did not last more a few days, by 9 comet's behavior indistinguishable pre-impact behavior; (iv) were interesting...
We conducted a spectroscopic survey of cometary volatiles with the Infrared Camera on board Japanese infrared satellite AKARI in wavelength range from 2.5 to 5 μm. In our survey, 18 comets, including both Oort cloud comets and Jupiter-family were observed period 2008 June 2010 January, most which at least twice. The prominent emission bands spectra are fundamental vibrational water (H2O) 2.7 μm carbon dioxide (CO2) 4.3 band monoxide (CO) around 4.7 broad feature, probably related...
We quantified eight parent volatiles (H 2 O, C H 6 , HCN, CO, CH 3 OH, and 4 ) in the Jupiter-family comet Tempel 1 using high-dispersion infrared spectroscopy wavelength range 2.8 to 5.0 micrometers. The abundance ratio for ethane was significantly higher after impact, whereas those methanol hydrogen cyanide were unchanged. ratios ejecta are similar most Oort cloud comets, but acetylene lower by a factor of about 2. These results suggest that volatile ices comets originated common region...
We describe recent results on the CO/CO2/H2O composition of comets together with a survey older literature (primarily for CO/H2O) and compare these models protoplanetary disk. Even currently small sample, there is wide dispersion in abundance ratios little if any systematic difference between Jupiter-family (JFCs) long-period Halley-type (LPCs HTCs). argue that cometary observations require reactions grain surfaces to convert CO CO2 also formation all types largely, but not entirely,...
Context. The Galactic centre is hazardous for stellar clusters because of the strong tidal force in action there. It believed that many were destroyed there and contributed stars to crowded field bulge nuclear cluster. However, development a realistic model predict long-term evolution complex inner Galaxy has proven difficult, observations surviving central region would provide crucial insights into destruction processes. Aims. Among known globular clusters, VVV CL002 closest centre, at 0.4...
Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths using techniques that are impossible with an in situ flyby. We report here such support of the EPOXI spacecraft flyby comet 103P/Hartley 2. The nucleus is small dark, exhibited a very rapidly changing rotation period. Prior to onset activity, period was ∼16.4 hr. Starting 2010 August changed from 16.6 hr near 19 December. With...
We performed high-dispersion optical spectroscopic observations of comet C/2012 S1 (ISON) using the High Dispersion Spectrograph (R = 72,000) at Subaru Telescope on UT 2013 November 15.6, during an outburst that started 14. Due to high gas-production rate NH2 outburst, we successfully detected weak emission lines 15NH2 and many strong 14NH2 in wavelength region from 5500 8200 Å. The ratio 14NH2/15NH2 is derived be 139 ± 38 (ISON). This close recently revealed based averaged spectrum 12...
The impact cratering process on a comet is controversial but holds the key for interpreting observations of Deep Impact collision with 9P/Tempel 1. Mid-infrared data from Cooled Mid-Infrared Camera and Spectrometer (COMICS) Subaru Telescope indicate that large-scale dust plume ejected by contained large mass (â¼10 6 kilograms) formed two wings approximately ±45° symmetric center, both consistent gravity as primary control its immediate aftermath. distribution in inner part plume, however,...
We report time-resolved measurements of the absolute and relative abundances eight parent volatiles (H2O, CH3OH, C2H6, C2H2, NH3, HCN, H2CO, HC3N) in coma 103P/Hartley 2 on UT 2010 November 4, date EPOXI spacecraft made its closest approach to comet, using high-dispersion infrared spectroscopy with NIRSPEC at W. M. Keck Observatory. Overall gas dust production increased by roughly 60% between 10:49 15:54. Differences spatial distributions species suggest icy sources different composition...
ABSTRACT We report spectroscopic observations of the resonance lines singly ionized 7 Be in blueshifted absorption line systems found post-outburst spectra two classical novae—V5668 Sgr (Nova Sagittarii 2015 No. 2) and V2944 Oph Ophiuchi 2015). The unstable isotope should have been created during thermonuclear runaway (TNR) these novae decayed to form Li within a short period (a half-life 53.22 days). These confirmations are second third ones following first case V339 Del by Tajitsu et al....
Abstract The recent discovery of “ultrahot” ( P < 1 day) Neptunes has come as a surprise: some these planets have managed to retain gaseous envelopes despite being close enough their host stars trigger strong photoevaporation and/or Roche lobe overflow. Here, we investigate atmospheric escape in LTT 9779b, an ultrahot Neptune with volatile-rich envelope. We observed two transits this planet using the newly commissioned WINERED spectrograph R ∼ 68,000) on 6.5 m Clay/Magellan II Telescope,...
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...
Abstract Comet C/2017 K2 (Pan-STARRS) provided a rare opportunity to investigate the evolution of coma composition and outgassing patterns over transitional heliocentric distance ( R h ) range where activity drivers in comets are thought change from “hypervolatile” (CO, CH 4 , C 2 H 6 and/or CO )-dominated O-dominated. We performed high-resolution <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>λ</mml:mi> </mml:math> / <mml:mi...
Coronagraphic imaging for the Herbig Ae star, HD 142527, was performed using Imager with Adaptive Optics (CIAO) on 8.2 m Subaru Telescope. The images were obtained in H2O ice filter (λ = 3.08 μm) adaptive optics (AO), and L' band without AO. Combining these data previous observational results H K bands, we derived spectra of scattered light from circumstellar disk around 142527 detected an absorption feature spectra. This result can be explained by presence silicate grains ∼1 μm size,...
The isotopic ratios are diagnostics for the physico-chemical conditions governing molecular formation. In comets, 14N/15N have been measured from HCN in three comets and CN more than 20 comets. Those enriched 15N compared to Sun by a factor of ∼3, small diversity do not depend on dynamical type origin this high 15N-fractionation is still debate because probably comes only HCN, but also other materials (such as polymers or organic dusts) coma. Consequently, an interpretation cometary quite...
Abstract A major upgrade to the NIRSPEC instrument at Keck II telescope was successfully completed in time for near-infrared spectroscopic observations of comet 46P/Wirtanen during its exceptionally close flyby Earth 2018 December. These studies determined abundances several volatiles, including C 2 H , 6 CH 3 OH, NH HCN, CO, and O. Long-slit spatial distributions gas rotational temperature column density are diagnostic presence icy grains coma understanding if different volatiles associated...
A high-dispersion spectrum of Comet C/1999S4 (LINEAR) was obtained in the optical region with spectrograph on Subaru telescope when comet 0.863 astronomical units from Sun before its disintegration. We high signal-to-noise ratio emission lines cometary NH2 bands which an ortho-to-para (OPR) 3.33 +/- 0.07 derived basis a fluorescence excitation model. Assuming that mainly originates ammonia through photodissociation, OPR molecules should reflect ammonia, provides information environment...
The ortho-to-para abundance ratio (OPR) of cometary molecules is considered to be one the primordial characteristics ices. We present OPRs ammonia (NH3) in 15 comets based on optical high-dispersion spectroscopic observations NH2, which a photodissociation product gaseous coma. were mainly carried out with VLT/UVES. OPR estimated from NH2 (0, 9, 0) vibronic band. absorption lines by telluric atmosphere are corrected and C2 emission blended removed our analysis. show cluster between 1.1 1.2...
Ammonia is a major reservoir of nitrogen atoms in cometary materials. However, detections ammonia comets are rare, with several achieved at radio wavelengths. A few more were obtained through near-infrared observations (around the 3 μm wavelength region), but moderate relative velocity shifts required to separate emission lines from telluric absorption region. On other hand, amidogen radical (NH2—a photodissociation product coma) also shows rovibrational Thus, gas production rates for can be...