Ilseung Han
A5029220016- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Molecular Spectroscopy and Structure
- Atmospheric Ozone and Climate
- Phase Equilibria and Thermodynamics
- Solar and Space Plasma Dynamics
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Advanced Chemical Physics Studies
- Superconducting Materials and Applications
- High-pressure geophysics and materials
- Nuclear physics research studies
- Astronomical Observations and Instrumentation
- Quantum Chromodynamics and Particle Interactions
- Thermodynamic properties of mixtures
- Atomic and Molecular Physics
- SAS software applications and methods
Korea University of Science and Technology
2018-2024
Korea Astronomy and Space Science Institute
2017-2024
Kyungpook National University
2017
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...
Context. Molecular filaments and hubs have received special attention recently thanks to new studies showing their key role in star formation. While the (column) density velocity structures of both been carefully studied, magnetic field (B-field) properties yet be characterized. Consequently, B-fields formation evolution hub-filament systems is not well constrained. Aims. We aim understand B-field its interplay with turbulence gravity dynamical NGC 6334 filament network that harbours...
Abstract While dust disks around optically visible, Class II protostars are found to be vertically thin, when and how settles the midplane unclear. As part of Atacama Large Millimeter/submillimeter Array large program, Early Planet Formation in Embedded Disks, we analyze edge-on, embedded, I protostar IRAS 04302+2247, also nicknamed “Butterfly Star.” With a resolution 0.″05 (8 au), 1.3 mm continuum shows an asymmetry along minor axis that is evidence thick geometrically disk viewed nearly...
Abstract We present observations of the Class 0 protostar IRAS 16544–1604 in CB 68 from “Early Planet Formation Embedded Disks (eDisk)” ALMA Large program. The target continuum and lines at 1.3 mm with an angular resolution ∼5 au. image reveals a dusty protostellar disk radius ∼30 au seen close to edge-on asymmetric structures along both major minor axes. While asymmetry axis can be interpreted as effect dust flaring, comes real nonaxisymmetric structure. C 18 O cubes clearly show gas that...
Constraining the physical and chemical structure of young embedded disks is crucial to understanding earliest stages planet formation. As part Early Planet Formation in Embedded Disks Atacama Large Millimeter/submillimeter Array Program, we present high spatial resolution ($\sim$0$.\!\!^{\prime\prime}$1 or $\sim$15 au) observations 1.3 mm continuum $^{13}$CO $J=$ 2-1, C$^{18}$O SO $J_N=$ $6_5$-$5_4$ molecular lines toward disk around Class I protostar L1489 IRS. The emission shows a...
Abstract We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the Class I source Oph IRS 63 in context Early Planet Formation Embedded Disks large program. Our ALMA show a myriad protostellar features, such as shell-like bipolar outflow (in 12 CO), an extended rotating envelope structure 13 streamer connecting to disk C 18 O), and several small-scale spiral structures seen toward edge dust continuum SO). By analyzing velocity pattern CO O, we measure mass M ⋆ = 0.5...
Studying the physical and chemical conditions of young embedded disks is crucial to constrain initial for planet formation. Here, we present Atacama Large Millimeter/submillimeter Array (ALMA) observations dust continuum at $\sim$0.06" (8 au) resolution molecular line emission $\sim$0.17" (24 toward Class 0 protostar L1527 IRS from Program eDisk (Early Planet Formation in Embedded Disks). The smooth without substructures, but asymmetric along both major minor axes disk as previously...
Abstract Precise estimates of protostellar masses are crucial to characterize the formation stars low down brown dwarfs (BDs; M * < 0.08 ☉ ). The most accurate estimation mass uses Keplerian rotation in circumstellar disk around protostar. To apply method a protostar at low-mass end, we have observed Class 0 IRAS 16253-2429 using Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum an angular resolution 0.″07 (10 au), and 12 CO, C 18 O, 13 CO ( J = 2–1), SO N 6 5 −5 4 )...
Abstract We performed radiative transfer calculations and observing simulations to reproduce the 1.3 mm dust-continuum C 18 O (2–1) images in Class I protostar R CrA IRS7B-a, observed with ALMA Large Program “Early Planet Formation Embedded Disks (eDisk).” found that a dust disk model passively heated by central cannot peak brightness temperature of continuum emission (∼195 K), regardless assumptions about opacity. Our calculation suggests viscous accretion heating is required high...
We present new observations of the active star-formation region NGC 1333 in Perseus molecular cloud complex from James Clerk Maxwell Telescope B-Fields In Star-forming Region Observations (BISTRO) survey with POL-2 instrument. The BISTRO data cover entire (~1.5 pc x 2 pc) at 0.02 resolution and spatially resolve polarized emission individual filamentary structures for first time. inferred magnetic field structure is as a whole, each filament aligned different position angles relative to...
We report 850~$\mu$m dust polarization observations of a low-mass ($\sim$12 $M_{\odot}$) starless core in the $\rho$ Ophiuchus cloud, C, made with POL-2 instrument on James Clerk Maxwell Telescope (JCMT) as part JCMT B-fields In STar-forming Region Observations (BISTRO) survey. detect an ordered magnetic field projected plane sky core. The across $\sim$0.1~pc shows predominant northeast-southwest orientation centering between $\sim$40$^\circ$ to $\sim$100$^\circ$, indicating that is well...
Abstract We present 850 μ m polarimetric observations toward the Serpens Main molecular cloud obtained using POL-2 polarimeter on James Clerk Maxwell Telescope as part of B-fields In STar-forming Region Observations survey. These probe magnetic field morphology about 6000 au scales, which consists cores and six filaments with different physical properties such density star formation activity. Using histogram relative orientation (HRO) technique, we find that fields are parallel to in...
Abstract The magnetic field of a molecular cloud core may play role in the formation circumstellar disks core. We present morphologies protostellar cores 16 targets Atacama Large Millimeter/submillimeter Array large program “Early Planet Formation Embedded Disks (eDisk),” which resolved their with 7 au resolutions. 0.1 pc scale were inferred from James Clerk Maxwell Telescope POL-2 observations. mean orientations and angular dispersions fields dense are measured compared radii 1.3 mm...
Abstract We have obtained sensitive dust continuum polarization observations at 850 μ m in the B213 region of Taurus using POL-2 on SCUBA-2 James Clerk Maxwell Telescope as part B -fields STar-forming Region Observations (BISTRO) survey. These allow us to probe magnetic field ( -field) high spatial resolution (∼2000 au or ∼0.01 pc 140 pc) two protostellar cores (K04166 and K04169) one prestellar core (Miz-8b) that lie within filament. Using Davis–Chandrasekhar–Fermi method, we estimate...
Abstract We have observed the Class 0/I protostellar system Ced110 IRS4 at an angular resolution of 0.″05 (∼10 au) as part Atacama Large Millimeter/submillimeter Array large program, Early Planet Formation in Embedded Disks. The 1.3 mm dust continuum emission reveals that is a binary with projected separation ∼250 au. emissions associated main source and its companion, named IRS4A IRS4B, respectively, exhibit disk-like shapes likely arise from disks around protostars. has radius ∼110 au...
Abstract Protostellar disks are an ubiquitous part of the star formation process and future sites planet formation. As Early Planet Formation in Embedded Disks large program, we present high angular resolution dust continuum (∼40 mas) molecular line (∼150 observations Class 0 protostar IRAS 15398–3359. The is small, compact, centrally peaked, while more extended structures found outflow directions. We perform a 2D Gaussian fitting find deconvolved size 2 σ radius disk to be 4.5 × 2.8 au 3.8...
Abstract We report 850 μ m continuum polarization observations toward the filamentary high-mass star-forming region NGC 2264, taken as part of B -fields In STar forming Regions Observations large program on James Clerk Maxwell Telescope. These data reveal a well-structured nonuniform magnetic field in 2264C and 2264D regions with prevailing orientation around 30° from north to east. Field strength estimates virial analysis major clumps indicate that is globally dominated by gravity, while...
The latest generation of Galactic-plane surveys is enhancing our ability to study the effects galactic environment upon process star formation. We present first data from CO Heterodyne Inner Milky Way Plane Survey 2 (CHIMPS2). CHIMPS2 a survey that will observe Galaxy, Central Molecular Zone (CMZ), and section Outer Galaxy in $^{12}$CO, $^{13}$CO, C$^{18}$O $(J = 3\rightarrow2)$ emission with Array Receiver Program on James Clerk Maxwell Telescope (JCMT). presented here are look towards CMZ...
Abstract We report the first high spatial resolution measurement of magnetic fields surrounding LkH α 101, part Auriga–California molecular cloud. The observations were taken with POL-2 polarimeter on James Clerk Maxwell Telescope within framework B-fields In Star-forming Region Observations (BISTRO) survey. Observed polarization thermal dust emission at 850 μ m is found to be mostly associated redshifted gas component field displays a relatively complex morphology. Two variants...
Abstract We present high-resolution Karl G. Jansky Very Large Array (VLA) observations of the protostar L1527 IRS at 7 mm, 1.3 cm, and 2 cm wavelengths. detect edge-on dust disk all three wavelengths find that it is asymmetric, with southern side brighter than northern side. confirm this asymmetry through analytic modeling also flared mm. test data against models including gap features in intensity profile, though we cannot rule such out, they do not provide a statistically significant...
We study the HII regions associated with NGC 6334 molecular cloud observed in sub-millimeter and taken as part of B-fields In STar-forming Region Observations (BISTRO) Survey. particular, we investigate polarization patterns magnetic field morphologies these regions. Through pattern pressure calculation analyses, several bubbles indicate that gas lines have been pushed away from bubble, toward an almost tangential (to bubble) morphology. densest 6334, where morphology is similar to...
Abstract Asymmetric and narrow infalling structures, often called streamers, have been observed in several Class 0/I protostars, which is not expected the classical star formation picture. Their origin impact on disk remain observationally unclear. By combining data from James Clerk Maxwell Telescope (JCMT) Atacama Large Millimeter/submillimeter Array (ALMA), we investigate physical properties of streamers parental dense core 0 protostar, IRAS 16544–1604. Three prominent associated to with...
Abstract We present the 850 μ m polarization observations toward IC 5146 filamentary cloud taken using Submillimetre Common-User Bolometer Array 2 (SCUBA-2) and its associated polarimeter (POL-2), mounted on James Clerk Maxwell Telescope, as part of B -fields In STar forming Regions Observations. This work is aimed at revealing magnetic field morphology within a core-scale (≲1.0 pc) hub-filament structure (HFS) located end parsec-scale filament. To investigate whether observed traces in HFS,...
We present the results of simultaneous 450 $\mu$m and 850 polarization observations toward massive star forming region NGC 2071IR, a target BISTRO (B-fields in Star-Forming Region Observations) Survey, using POL-2 polarimeter SCUBA-2 camera mounted on James Clerk Maxwell Telescope. find pinched magnetic field morphology central dense core region, which could be due to rotating toroidal disk-like structure bipolar outflow originating from young stellar object, IRS 3. Using modified...
We present 850 $\mu$m dust polarization observations of the massive DR21 filament from B-fields In STar-forming Region Observations (BISTRO) survey, using POL-2 polarimeter and SCUBA-2 camera on James Clerk Maxwell Telescope. detect ordered magnetic fields perpendicular to parsec-scale ridge main filament. sub-filaments, are mainly parallel filamentary structures smoothly connect compare Planck study field 0.1--10 pc scales. The revealed in data well aligned with those data, indicating a...