A5089553032- Astrophysics and Star Formation Studies
- Molecular Spectroscopy and Structure
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Atmospheric Ozone and Climate
- Advanced Chemical Physics Studies
- Reproductive Biology and Fertility
- Astronomy and Astrophysical Research
- Spectroscopy and Laser Applications
- Spacecraft and Cryogenic Technologies
- Phase Equilibria and Thermodynamics
- Quantum, superfluid, helium dynamics
- Gamma-ray bursts and supernovae
- Inorganic Fluorides and Related Compounds
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- High-pressure geophysics and materials
- SAS software applications and methods
- Atmospheric chemistry and aerosols
- Advanced Combustion Engine Technologies
- Methane Hydrates and Related Phenomena
- Thermodynamic properties of mixtures
- Solar and Space Plasma Dynamics
- Chemical Thermodynamics and Molecular Structure
- Atomic and Molecular Physics
The University of Tokyo
1997-2025
University of Yamanashi
2000-2024
Kyoto University
2008-2024
Tokyo University of Science
1997-2024
National Livestock Breeding Center
2008-2019
University of Tsukuba
2015-2018
Kobe University
2007-2017
Naval Research Laboratory Information Technology Division
2016
Japan Meteorological Agency
2009
Osaka City University
2004-2005
`Water In Star-forming regions with Herschel' (WISH) is a key program on the Herschel Space Observatory designed to probe physical and chemical structure of young stellar objects using water related molecules follow abundance from collapsing clouds planet-forming disks. About 80 sources are targeted covering wide range luminosities evolutionary stages, cold pre-stellar cores warm protostellar envelopes outflows disks around stars. Both HIFI PACS instruments used observe variety lines H2O,...
(Abridged) Protoplanetary disks are vital objects in star and planet formation, possessing all the material which may form a planetary system orbiting new star. We investigate synthesis of complex organic molecules (COMs) to constrain achievable chemical complexity predict species transitions be observable with ALMA. have coupled 2D model protoplanetary disk around T Tauri gas-grain network including COMs. compare synthesised line intensities calculated column densities observations...
Planets form and obtain their compositions in dust gas-rich disks around young stars, the outcome of this process is intimately linked to disk chemical properties. The distributions molecules across regulate elemental planets, including C/N/O/S ratios metallicity (O/H C/H), as well access water prebiotically relevant organics. Emission from also encodes information on ionization levels, temperature structures, kinematics, gas surface densities, which are all key ingredients evolution planet...
Here we present high resolution (15-24 au) observations of CO isotopologue lines from the Molecules with ALMA on Planet-forming Scales (MAPS) Large Program. Our analysis employs $^{13}$CO and C$^{18}$O ($J$=2-1), (1-0), C$^{17}$O (1-0) line five protoplanetary disks. We retrieve gas density distributions, using three independent methods: (1) a thermo-chemical modeling framework based data, broadband spectral energy distribution, mm-continuum emission; (2) an empirical temperature...
We present an overview of the Large Program, ``Early Planet Formation in Embedded Disks (eDisk)'', conducted with Atacama Millimeter/submillimeter Array (ALMA). The ubiquitous detections substructures, particularly rings and gaps, protoplanetary disks around T Tauri stars raise possibility that at least some planet formation may have already started during embedded stages star formation. In order to address exactly how when is initiated, program focuses on searching for substructures 12...
We investigate molecular evolution in a star-forming core that is initially hydrostatic starless and collapses to form low-mass protostar. The results of one-dimensional radiation-hydrodynamics calculation are adopted as physical model the core. first derive radii at which CO large organic species sublimate. sublimation central region starts shortly before formation When protostar born, radius extends 100 AU, inside $\lesssim 10$ AU hotter than K, some evaporate. calculate temporal variation...
We have investigated the evolution and distribution of molecules in collapsing prestellar cores via numerical chemical models, adopting Larson-Penston solution its delayed analogs to study collapse. Molecular abundances distributions a core are determined by balance among dynamical, chemical, adsorption timescales. When central density nH with flow rises 3 × 106 cm-3, CCS CO column densities calculated show holes radius 7000 4000 AU, respectively, while N2H+ is centrally peaked. These...
We have investigated molecular distributions in protoplanetary disks, adopting a disk model with temperature gradient the vertical direction. The produces sufficiently high abundances of gaseous CO and HCO+ to account for line observations T Tauri stars using sticking probability unity without assuming any non-thermal desorption. In regions radius AU, which we are concerned, increases increasing height from midplane. warm intermediate layer, there significant amounts molecules owing thermal...
The gravitational collapse of a spherical cloud core is investigated by numerical calculations. initial conditions the lie close to critical Bonnor-Ebert sphere with central density ~104 cm-3 in one model (α = 1.1), while gravity overwhelms pressure other 4.0), where α internal gravity-to-pressure ratio. 1.1 shows reasonable agreement observed velocity field prestellar cores. Molecular distributions cores are calculated solving chemical reaction network that includes both gas-phase and...
We report Atacama Large Millimeter/submillimeter Array (ALMA) cycle 0 observations of the C18O (J = 2–1), SO (JN 65–54), and 1.3 mm dust continuum toward L1527 IRS, a class solar-type protostar surrounded by an infalling rotating envelope. emission shows strong redshifted absorption against bright associated with strongly suggesting infall motions in The envelope also rotates velocity mostly proportional to r−1, where r is radius, whereas rotation profile at innermost radius (∼54 AU) may be...
Water is a crucial molecule in molecular astrophysics as it controls much of the gas/grain chemistry, including formation and evolution more complex organic molecules ices. Pre-stellar cores provide original reservoir material from which future planetary systems are built, but few observational constraints exist on water its partitioning between gas ice densest cores. Thanks to high sensitivity Herschel Space Observatory, we report first detection vapor at spectral resolution toward dense...
Detailed models for the density and temperature profiles of gas dust in protoplanetary disks are constructed by taking into account X-ray ultraviolet (UV) irradiation from a central T Tauri star, as well size growth settling toward disk midplane. The spatial distributions grains numerically computed solving coagulation equation particles. level populations line emission molecular hydrogen calculated using derived physical structure disks. is dominant heating source inner region surface...
We investigate the molecular evolution and D/H abundance ratios that develop as star formation proceeds from a dense cloud core to protostellar core, by solving gas–grain reaction network applied one-dimensional radiative hydrodynamic model with infalling fluid parcels. Spatial distributions of gas ice-mantle species are calculated at first-core stage, times after birth protostar. Gas-phase methanol methane more abundant than CO radii r ≲ 100 AU in but gradually decrease time, while...
We have conducted ALMA observations in the 1.3 mm continuum and 12CO (2-1), C18O (2-1) SO (5_6-4_5) lines toward L1489 IRS, a Class I protostar surrounded by Keplerian disk an infalling envelope. The is clearly identified emission, its outer radius (~700 AU) mass (~0.005 Msun) are comparable to those of disks around T Tauri stars. protostellar estimated be 1.6 Msun with inclination angle 66 deg. In addition disk, there blueshifted redshifted off-axis protrusions seen emission pointing north...
ABSTRACT The first detection of gas-phase methanol in a protoplanetary disk (TW Hya) is presented. In addition to being one the largest molecules detected disks date, also organic molecule with an unambiguous ice chemistry origin. stacked emission, as observed Atacama Large Millimeter/submillimeter Array, spectrally resolved and across six velocity channels ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>></mml:mo> <mml:mn>3</mml:mn>...
We investigate the impact of photochemistry and X-ray ionization on molecular composition of, fraction in, a protoplanetary disk surrounding typical T Tauri star. use sophisticated physical model, which includes robust treatment radiative transfer UV radiation, calculate time-dependent chemical structure using comprehensive network. In previous work, we approximated ionization; here, recalculate photoreaction rates explicit wavelength spectrum wavelength-dependent reaction cross sections....
The deuterium enrichment of molecules is sensitive to their formation environment. Constraining patterns chemistry in protoplanetary disks therefore useful for probing how material inherited or reprocessed throughout the stages star and planet formation. We present ALMA observations at $\sim0.6"$ resolution DCO$^+$, H$^{13}$CO$^+$, DCN, H$^{13}$CN full around T Tauri stars AS 209 IM Lup, transition V4046 Sgr LkCa 15, Herbig Ae MWC 480 HD 163296. also HCN Lup disk. H$^{13}$CO$^+$ are detected...
Subarcsecond images of the rotational line emissions CCH, CS, H2CO, and CH3OH have been obtained toward low-mass protostar IRAS 04368+2557 in L1527 as one early science projects Atacama Large Millimeter/submillimeter Array. The intensity distributions CCH CS show a double-peaked structure along edge-on envelope with dip position, whereas those H2CO are centrally peaked. By analyzing position–velocity diagrams envelope, found to reside mainly where gas is infalling conservation its angular...
In a protoplanetary disk, combination of thermal and non-thermal desorption processes regulate where volatiles are liberated from icy grain mantles into the gas phase. Non-thermal should result in volatile-enriched disk-regions complete freeze-out is otherwise expected. We present Atacama Large Millimeter/Submillimeter Array observations disk around young star IM Lup 1.4 mm continuum, C18O 2–1, H13CO+ 3–2 DCO+ emission at ∼05 resolution. The images these dust tracers clearly resolved. line...
The Molecules with ALMA at Planet-forming Scales (MAPS) Large Program provides a unique opportunity to study the vertical distribution of gas, chemistry, and temperature in protoplanetary disks around IM Lup, GM Aur, AS 209, HD 163296, MWC 480. By using asymmetry molecular line emission relative disk major axis, we infer height ($z$) above midplane as function radius ($r$). Using this method, measure emitting surfaces for suite CO isotopologues, HCN, C$_2$H. We find that $^{12}$CO traces...
ABSTRACT We report the first evidence of a hot corino in Bok globule. This is based on ALMA observations 1.2 mm band toward low-mass Class 0 protostar IRAS 19347+0727 B335. Saturated complex organic molecules (COMs), CH 3 CHO, HCOOCH , and NH 2 are detected compact region within few 10 au around protostar. Additionally, OCH C H 5 OH, CN, COCH tentatively detected. Carbon-chain related molecules, CCH c-C also found this source, whose distributions extended over scale 100 au. On other hand,...