A5039211341- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Molecular Spectroscopy and Structure
- Astro and Planetary Science
- Atmospheric Ozone and Climate
- Astronomy and Astrophysical Research
- Spectroscopy and Laser Applications
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Advanced Chemical Physics Studies
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Advanced Combustion Engine Technologies
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Phase Equilibria and Thermodynamics
- Atomic and Molecular Physics
- Ionosphere and magnetosphere dynamics
- Particle Accelerators and Free-Electron Lasers
- Space Exploration and Technology
- Planetary Science and Exploration
- Geomagnetism and Paleomagnetism Studies
- Calibration and Measurement Techniques
- Spacecraft and Cryogenic Technologies
Institute of Astronomy and Astrophysics, Academia Sinica
2016-2025
Theodore Roosevelt High School
2025
National Taiwan University
2014-2024
Hitotsubashi University
1993-2007
National Astronomical Observatory of Japan
2001-2003
The Graduate University for Advanced Studies, SOKENDAI
2001
Tohoku University
1986-1987
Toho University
1980
We present ~2''-4'' aperture synthesis observations of the circumstellar disk surrounding nearby young star TW Hya in CO J = 2-1 and 3-2 lines associated dust continuum obtained with partially completed Submillimeter Array. The extent peak flux 230 345 GHz emission follow closely predictions irradiated accretion model Calvet et al. resolved molecular line extends to a radius at least 200 AU, full visible scattered light, shows clear pattern Keplerian rotation. Comparison images...
In recent years, the disk populations in a number of young star-forming regions have been surveyed with ALMA. Understanding properties and their correlation those central star is critical to understand planet formation. particular, decrease average measured dust mass age region has observed. We conducted high-sensitivity continuum ALMA observations 43 Class II stellar objects CrA at 1.3 mm (230 GHz). The typical spatial resolution 0.3". fluxes are used estimate masses disks, survival...
Abstract Protostellar outflows and jets are almost ubiquitous characteristics during the mass accretion phase encode history of stellar accretion, complex organic molecule (COM) formation, planet formation. Episodic likely connected to episodic through disk. Despite importance, studies on ejection links have not been done yet in a systematic fashion using high-sensitivity high-resolution observations. To explore mechanisms chronologies events, we investigated 39 fields containing protostars...
view Abstract Citations (195) References (65) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Molecular Cloud Cores in the Orion A Cloud. I. Nobeyama CS (1--0) Survey Tatematsu, Ken'ichi ; Umemoto, Tomofumi Kameya, Osamu Hirano, Naomi Hasegawa, Tetsuo Hayashi, Masahiko Iwata, Takahiro Kaifu, Norio Mikami, Hitomi Murata, Yasuhiro Nakano, Makoto Takenori Ohashi, Nagayoshi Sunada, Kazuyoshi Takaba, Hiroshi Yamamoto, Satoshi first high-resolution survey of...
The protostellar jet driven by L1448C was observed in the SiO J = 8–7 and CO 3–2 lines, 350 GHz dust continuum at ∼1'' resolution with Submillimeter Array. A narrow from northern source L1448C(N) high-velocity CO. consists of a chain emission knots an inter-knot spacing ∼2'' (500 AU) semi-periodic velocity variation. These are likely to be internal bow shocks beam that were formed due periodic variation ejection period ∼15–20 yr. innermost pairs knots, which significant map but barely seen...
HH 211 is a nearby young protostellar system with highly collimated jet. We have mapped it in 352 GHz continuum, SiO (J = 8 − 7), and HCO+ 4 3) emission at up to ∼02 resolution the Submillimeter Array (SMA). The continuum source now resolved into two sources, SMM1 SMM2, separation of ∼ 84 AU. seen center jet, probably tracing (inner) dusty disk around protostar driving SMM2 southwest may trace an envelope-disk small binary companion. A flattened radius 80 AU perpendicular jet axis. Its...
HH 212 is a nearby (400 pc) Class 0 protostellar system showing several components that can be compared with theoretical models of core collapse. We have mapped it in 350 GHz continuum and HCO+ J=4-3 emission ALMA at up to ~ 0.4" resolution. A flattened envelope compact disk are seen around the central source, as before. The kinematics shows infalling small rotation (i.e., spiraling) into thus identified pseudodisk magnetized Also, rotating rotationally supported. In addition, account for...
We present our observational results of the 1.1 mm continuum and HCO+ (3-2) line in HL Tau at angular resolutions 0.1" obtained with ALMA data analysis 2.9 (1-0) lines disk. The Keplerian rotation disk is well resolved emission, stellar mass estimated to be 2.1+/-0.2 Msun a inclination angle 47 deg. radial profiles column density excitation temperature are measured LTE two transitions emission. An gas gap radius 30 au, where drops by factor 4-8, found profile, coincident dust traced No other...
In the earliest (so-called "Class 0") phase of Sun-like (low-mass) star formation, circumstellar disks are expected to form, feeding protostars. However, these difficult resolve spatially because their small sizes. Moreover, there theoretical difficulties in producing retarding effects magnetic fields on rotating, collapsing material "magnetic braking"). With Atacama Large Millimeter/submillimeter Array (ALMA), it becomes possible uncover and study them detail. HH 212 is a very young...
Episodic accretion has been used to explain the wide range of protostellar luminosities, but its origin and influence on star forming process are not yet fully understood. We present an ALMA survey N$_2$H$^+$ ($1-0$) HCO$^+$ ($3-2$) toward 39 Class 0 I sources in Perseus molecular cloud. destroyed via gas-phase reactions with CO H$_2$O, respectively, thus tracing H$_2$O snowline locations. A location at a much larger radius than that expected from current luminosity suggests burst occurred...
Class II methanol masers are signs of massive young stellar objects (MYSOs). Recent findings show that MYSO accretion bursts cause flares these masers. Thus, maser monitoring can be used to identify such bursts. Burst-induced SED changes provide valuable information on a very intense phase high-mass star formation. In mid-January 2019, flare the G358.93-0.03 was reported. ALMA and SMA imaging resolved core forming region proved association with brightest continuum source MM1. However, no...
Abstract In the past decade, ALMA observations of protoplanetary disks revealed various substructures including gaps and rings. Their origin may be probed through statistical studies their physical properties. We present analyses archival Band 6 continuum data 43 (39 Class II four Herbig Ae) in Taurus–Auriga region. employ a novel 2D super-resolution imaging technique based on sparse modeling to obtain images with high fidelity spatial resolution. As result, we have obtained resolutions...
We report interferometric observations of two embedded protostar candidates, IRAS 04169+2702 and 04365+2535 (TMC-1A), in the Taurus molecular cloud. The C18O J = 1-0 emission from reveals a flattened envelope 2200 AU × 1100 size; there is velocity gradient along elongation axis, which turn perpendicular to outflow direction. Since rotational corrected for inclination, 0.23 km s-1 at 370 AU, gives an unacceptably small dynamical mass 0.02 M☉ within that radius, we speculate additional radial...
Arcsecond-resolution spectral observations toward the protobinary system IRAS 16293-2422 at 344 and 354 GHz were conducted using Submillimeter Array. Complex organic molecules such as CH3OH HCOOCH3 detected. Together with rich inventory revealed, it clearly indicates existence of two, rather than one, compact hot molecular cores (smaller or equal to 400 AU in radius) associated each components identified by their dust continuum emission inner star-forming core.
We have mapped the SiO J = 5-4 line at 217 GHz from HH 211 molecular outflow with Submillimeter Array (SMA). The high-resolution map (16 × 09) shows that emission comes central narrow jet along axis a width of ~08 (~250 AU) FWHM. consists chain knots separated by 3''-4'' (~1000 AU), and most counterparts in shocked H2 seen new, deep VLT near-infrared image outflow. A innermost pair been discovered just ±2'' star. ratio between data upper limits 1-0 Chandler & Richer suggests these...
HH 212 is a nearby (460 pc) protostellar jet discovered in H$_2$ powered by Class 0 source, IRAS 05413-0104, the L1630 cloud of Orion. It highly collimated and symmetric with matched pairs bow shocks on either side source. We have mapped it 850 $μ$m continuum, SiO ($J=8-7$), CO ($J=3-2$), SO ($N_J=8_9-7_8$), HCO$^+$ ($J = 4-3$), H$^{13}$CO$^+$ 4-3$) emission simultaneously at $\sim$ 1$''$ resolution Submillimeter Array (SMA). Thermal dust seen continuum around mainly arising from an inner...
HH 212 is a nearby (400 pc), highly collimated protostellar jet powered by class 0 source in Orion. Our previous observations with the Submillimeter Array have shown that inner part of well traced SiO (J = 8–7) shock emission. Here we present at higher angular resolution ~0.35'', searching for rotation better resolved structures and kinematics. The has transverse width ~80-140 AU. two knots closest to are now spatially into bow shocks. one south resolved; precessing or an unseen wide-angle...
We are motivated by the recent measurements of dust opacity indices beta around young stellar objects (YSOs), which suggest that efficient grain growth may have occurred earlier than Class I stage. The present work makes use abundant archival interferometric observations at submillimeter,millimeter, and centimeter wavelength bands to examine signatures in dense inner regions (<1000 AU) nine 0 YSOs. A systematic data analysis is performed derive temperatures, optical depths, based on...
The low dust temperatures (<14 K) of Planck Galactic cold clumps (PGCCs) make them ideal targets to probe the initial conditions and very early phase star formation. "TOP-SCOPE" is a joint survey program targeting ∼2000 PGCCs in J = 1–0 transitions CO isotopologues ∼1000 850 μm continuum emission. objective surveys (SMT 10 m, KVN 21 NRO 45 m) statistically study occurring during formation evolution molecular clouds, across wide range environments. observations, data analysis, example science...
Abstract HH 212 is a nearby (400 pc) Class 0 protostellar system recently found to host “hamburger”-shaped dusty disk with radius of ∼60 au, deeply embedded in an infalling-rotating flattened envelope. We have spatially resolved this envelope-disk the Atacama Large Millimeter/submillimeter Array at up ∼16 au (0.″04) resolution. The envelope detected HCO + J = 4–3 down disk. Complex organic molecules (COMs) and doubly deuterated formaldehyde (D 2 CO) are above below within ∼40 central...
We introduce a new stacking method in Keplerian disks that (1) enhances signal-to-noise ratios (S/N) of detected molecular lines and (2) makes visible otherwise undetectable weak lines. Our technique takes advantage the rotational velocity pattern. It aligns spectra according to their different centroid velocities at positions disk stacks them. After aligning, signals are accumulated narrower range as compared original line width without alignment. Moreover, originally correlated noise...
Abstract We present (sub)millimeter imaging at 0.″5 resolution of the massive star-forming region G358.93−0.03 acquired in multiple epochs 2 and 3 months following recent flaring its 6.7 GHz CH OH maser emission. Using Submillimeter Array Atacama Large Millimeter/submillimeter Array, we have discovered 14 new Class II lines ranging frequency from 199 to 361 GHz, which originate mostly = 1 torsionally excited transitions include one transition. The latter detection provides first...
Abstract HH 211-mms is one of the youngest Class 0 protostellar systems in Perseus, at a distance ∼235 pc. We have mapped its central region up to ∼7 au (0.″03) resolution. A dusty disk seen deeply embedded flattened envelope, with an intensity jump dust continuum ∼350 GHz. It nearly edge-on and almost exactly perpendicular jet axis. has size ∼30 along major geometrically thick, indicating that (sub)millimeter light-emitting grains yet settle midplane. Its inner part expected transformed...