A5059353542- Astro and Planetary Science
- Isotope Analysis in Ecology
- Planetary Science and Exploration
- Atmospheric Ozone and Climate
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Nuclear Physics and Applications
- Spacecraft and Cryogenic Technologies
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Space Exploration and Technology
- Astronomical Observations and Instrumentation
- Molecular Spectroscopy and Structure
- Rocket and propulsion systems research
- Atmospheric and Environmental Gas Dynamics
- Mass Spectrometry Techniques and Applications
- Astronomy and Astrophysical Research
- High-pressure geophysics and materials
- Geomagnetism and Paleomagnetism Studies
- Advanced Chemical Physics Studies
- Maritime and Coastal Archaeology
- Astronomical and nuclear sciences
- Paleontology and Stratigraphy of Fossils
- SAS software applications and methods
- Solar and Space Plasma Dynamics
Kyoto Sangyo University
2012-2023
National Astronomical Observatory of Japan
2015-2019
University of Liège
2014-2017
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 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...
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...
Hyperactive comets are a small group of whose activity higher than expected. They seem to emit more water they should based on the size their nucleus and comet 46P/Wirtanen is one them. Investigating its composition evolution could provide clues about origins formation region in Solar nebulae. Given exceptional close approach 2018 46P Earth, we aim study as function heliocentric distances before after perihelion. We used both TRAPPIST telescopes monitor for almost year with broad-band...
ABSTRACT The water production rate of a comet is one the fundamental parameters necessary to understand cometary activity when approaches Sun within 2.5 au, because most abundant icy material in nucleus. Wide-field imaging observations hydrogen Ly α emission 67P/Churyumov–Gerasimenko were performed by Lyman Alpha Imaging Camera (LAICA) on board 50 kg class micro spacecraft, Proximate Object Close Flyby with Optical Navigation ( PROCYON ), UT 2015 September 7.40, 12.37, and 13.17...
Abundance ratios of nuclear-spin isomers for cometary molecules having identical protons, such as water and ammonia, have been measured discussed from the viewpoint that they are primordial characters in comet. In case its ortho-to-para abundance ratio (OPR) is usually estimated OPRs NH2 because difficulty measuring OPR ammonia directly. We report our survey 26 comets. A weighted mean comets 1.12 ± 0.01 no significant difference found between Oort Cloud Jupiter-family These values correspond...
ABSTRACT We report on high-dispersion spectroscopy results of a classical nova V2659 Cyg (Nova 2014) that are taken 33.05 days after the V -band maximum. The spectrum shows two distinct blueshifted absorption systems originating from H i , Fe ii Ca ii, etc. radial velocities −620 km s −1 and −1100 to −1500 . higher velocity component corresponds P-Cygni features frequently observed in low-resolution spectra. Much larger numbers lines identified at lower velocity. These mainly originate...
We report on the first polarimetric study of (3200) Phaethon, target JAXA's DESTINY$^+$ mission, in negative branch to ensure its anhydrous nature and derive an accurate geometric albedo. conducted observations at low phase angles (Sun-target-observer angle, alpha = 8.8-32.4 deg) from 2021 October 2022 January found that Phaethon has a minimum polarization degree $P_{min}$ -1.3 +- 0.1 %, slope h 0.22 0.02 % deg$^{-1}$, inversion angle alpha$_0$ 19.9 0.3 deg. The derived albedo is $p_V$ 0.11...
2I/Borisov - hereafter 2I is the first visibly active interstellar comet observed in solar system, allowing us for time to sample composition of a building block from another system. We report on monitoring with UVES, high resolution optical spectrograph ESO Very Large Telescope at Paranal, during four months November 15, 2019 March 16, 2020. Our goal characterize activity and respect system comets. collected spectra 12 different epochs 2.1 au pre-perihelion 2.6 post perihelion. On December...
Abstract The Ortho-to-Para abundance ratio (OPR) of cometary molecules is considered to be one primordial characters comeary ices, which has information concerning their formation. In order determine the OPR ammonia (NH$_{3}$), high-dispersion spectra in optical wavelength region have been most powerful tool, since NH$_{2}$ a photo-dissociation product NH$_{3}$, and strong electronic transition region. Here we present an improved procedure derive (OPR NH$_{3}$ derived from that NH$_{2}$)...
The icy materials present in comets provide clues to the origin and evolution of our solar system planetary systems. High-resolution optical spectroscopic observations comet C/2014 Q2 (Lovejoy) were performed on 2015 January 11 (at 1.321 au pre-perihelion) with High Dispersion Spectrograph mounted Subaru Telescope Maunakea, Hawaii. We derive 14N/15N ratio NH2 (126 ± 25), as well ortho-to-para abundance ratios (OPRs) H2O+ ion (2.77 0.24) (3.38 0.07), which correspond nuclear spin temperatures...
The dust-forming nova V2676 Oph is unique in that it was the first to provide evidence of C_2 and CN molecules during its near-maximum phase CO early decline phase. Observations this have revealed slow evolution lightcurves also shown low isotopic ratios carbon (12C/13C) nitrogen (14N/15N) envelope. These behaviors indicate white dwarf (WD) star hosting a CO-rich WD rather than an ONe-rich (typically larger mass former). We performed mid-infrared spectroscopic photometric observations 2013...
Abstract Although high-resolution spectra of the CN red-system band are considered useful in cometary sciences, e.g., study isotopic ratios carbon and nitrogen volatiles, there have been few reports to date due lack ( R ≡ λ /Δ > 20,000) spectrographs near-infrared region around ∼1 μ m. Here, we present emission spectrum comet C/2013 R1 (Lovejoy), acquired by spectrograph WINERED mounted on 1.3 m Araki telescope at Koyama Astronomical Observatory, Kyoto, Japan. We applied our fluorescence...
The linear polarization degree (referred to the scattering plane, P_r) as a function of solar phase angle, {\alpha}, system objects is good diagnostic understand properties their surface materials. We report Pr Phaethon over wide range {\alpha} from 19.1 deg 114.3 in order better understanding its derived phase-polarization curve shows that maximum P_r, P_max, >42.4% at >114.3 deg, value significantly larger than those moderate albedo asteroids (P_max ~9%). classifies B-type polarimetric...
Dust grains of crystalline silicate, which are rarely presented in interstellar space, were found cometary nuclei. These silicates thought to have formed by annealing amorphous silicate or direct condensation gaseous materials near the Sun solar nebula, and incorporated into nuclei cold comet-forming region after radial transportation nebula. Abundances dust therefore expected be smaller farther from Sun. We aim better understand formation mechanism minerals comet 17P/Holmes based on its...
Abstract High-resolution spectropolarimetric observations of V339 Del were performed in the optical wavelength region every night from UT 2013 August 15.49 to 21.23 (corresponding pre- and near-maximum phases nova) reveal asymmetry nova ejecta shortly after explosion. Observed polarization spectra showed intrinsic line for H α , O i λ 777.3 nm, Si ii λλ 634.7, 637.1 addition continuum polarization. The on (+0.91 day post-discovery) indicates an expanding ejecta, which contains a torus...
Comet 21P/Giacobini-Zinner is a peculiar comet from the viewpoints of chemical and physical properties its dust grains. We conduct optical high-resolution spectroscopic observations comet. The intensity ratios forbidden oxygen lines (at 557.7, 630.0, 636.4 nm) ortho-to-para abundance (OPRs) water cations (H$_2$O$^+$) amidogen radicals (NH$_2$) are obtained while only upper limit for $^{14}$N/$^{15}$N in radical restricted. OPRs H$_2$O$^+$ NH$_2$ similar to those other comets, although real...
Abstract We report the new detection of 7 Be ii in ultraviolet spectra V5669 Sgr during its early decline phase (+24 and +28 d). identified three blueshifted absorption systems our spectra. The first two, referred to as low- high-velocity components, were noticeably among H i Balmer, Na D, Fe whose lower energies transients are low (<4 eV). third component was N , He C lines energy levels relatively high (9–21 at 3130.583 Å 3132.228 second components observations. No evidence suggested...
Isotopic ratios in comets are critical to understanding the origin of cometary material and physical chemical conditions early solar nebula. Comet C/2015 ER61 (PANSTARRS) underwent an outburst with a total brightness increase 2 magnitudes on night 2017 April 4. The sharp offered rare opportunity measure isotopic light elements coma this comet. We obtained two high-resolution spectra UVES/VLT nights 13 17. At time our observations, comet was fading gradually following outburst. measured...
Abstract High-resolution near-infrared ground-based spectroscopic observations of comet 67P/Churyumov–Gerasimenko near its maximum activity in 2021 were conducted from the W. M. Keck Observatory, using facility spectrograph NIRSPEC. 67P is best-studied to date because unprecedented detail and insights provided by Rosetta mission during 2014–2016. Because only where detailed abundances many coma volatiles measured situ, determining composition ground provides a unique opportunity interpret...