Hwihyun Kim
A5065794307- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Space Exploration and Technology
- Flood Risk Assessment and Management
- Atmospheric Ozone and Climate
- Hydrology and Watershed Management Studies
- Urban Stormwater Management Solutions
- CCD and CMOS Imaging Sensors
- Optical Systems and Laser Technology
- History and Developments in Astronomy
- Astrophysics and Cosmic Phenomena
- Spectroscopy and Laser Applications
- Planetary Science and Exploration
- Molecular Spectroscopy and Structure
- Radio Wave Propagation Studies
- Spacecraft Design and Technology
- Advanced MIMO Systems Optimization
- Geophysical Methods and Applications
Gemini North Observatory
2022-2025
NSF’s NOIRLab
2022-2025
Korea University
2008-2025
TechnipFMC (United States)
2024
Gemini South Observatory
2017-2022
Korea Astronomy and Space Science Institute
2014-2022
RELX Group (United States)
2020
Dayton Clinical Oncology Program
2020
Park University
2020
Capgemini (Netherlands)
2019
Merging neutron stars offer an exquisite laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of electromagnetic counterpart EM170817 to gravitational waves (GW170817) detected from merging stars. By synthesizing a panchromatic dataset, we demonstrate that are long-sought production site forging heavy elements by r-process nucleosynthesis. The weak gamma-rays seen dissimilar classical short gamma-ray bursts with...
The Legacy ExtraGalactic UV Survey (LEGUS) is a Cycle 21 Treasury program on the Hubble Space Telescope aimed at investigation of star formation and its relation with galactic environment in nearby galaxies, from scales individual stars to those ∼kiloparsec-size clustered structures. Five-band imaging near-ultraviolet I band Wide-Field Camera 3 (WFC3), plus parallel optical Advanced for Surveys (ACS), being collected selected pointings 50 galaxies within local 12 Mpc. filters used...
The PHANGS collaboration has been building a reference dataset for the multi-scale, multi-phase study of star formation and interstellar medium in nearby galaxies. With successful launch commissioning JWST, we can now obtain high-resolution infrared imaging to probe youngest stellar populations dust emission on scales clusters molecular clouds ($\sim$5-50 pc). In Cycle 1, is conducting an 8-band survey from 2-21$\mu$m 19 spiral CO(2-1) mapping, optical integral field spectroscopy, UV-optical...
The Immersion Grating Infrared Spectrometer (IGRINS) is a compact high-resolution near-infrared cross-dispersed spectrograph whose primary disperser silicon immersion grating. IGRINS covers the entire portion of wavelength range between 1.45 and 2.45μm that accessible from ground does so in single exposure with resolving power 40,000. Individual volume phase holographic (VPH) gratings serve as cross-dispersing elements for separate arms covering H K bands. On 2.7m Harlan J. Smith telescope...
We report the large effort which is producing comprehensive high-level young star cluster (YSC) catalogues for a significant fraction of galaxies observed with Legacy ExtraGalactic UV Survey (LEGUS) Hubble treasury program. present methodology developed to extract positions, verify their genuine nature, produce multiband photometry (from NUV NIR), and derive physical properties via spectral energy distribution fitting analyses. use nearby spiral galaxy NGC628 as test case demonstrating...
The first JWST observations of nearby galaxies have unveiled a rich population bubbles that trace the stellar feedback mechanisms responsible for their creation. Studying these therefore allows us to chart interaction between and interstellar medium, larger galactic flows needed regulate star formation processes globally. We present catalog in NGC628, visually identified using MIRI F770W PHANGS-JWST observations, use them statistically evaluate bubble characteristics. classify 1694...
Abstract A primary new capability of JWST is the ability to penetrate dust in star-forming galaxies identify and study properties young star clusters that remain embedded gas. In this Letter we combine infrared images taken with our optical Hubble Space Telescope (HST) starbursting barred (Seyfert2) spiral galaxy NGC 1365. We find has richest population massive any known within 30 Mpc, ∼30 are more than 10 6 M ⊙ younger Myr. Sixteen these newly discovered from observations. An examination...
Abstract We describe the survey design and science goals for One-hundred-deg 2 DECam Imaging in Narrowbands (ODIN), a NOIRLab using Dark Energy Camera (DECam) to obtain deep (AB ∼ 25.7) narrowband images over an unprecedented area of sky. The three custom-built filters, N 419, 501, 673, have central wavelengths 673 nm respective FWHM 7.5, 7.6, 10.0 nm, corresponding Ly α at z = 2.4, 3.1, 4.5 cosmic times 2.8, 2.1, 1.4 Gyr, respectively. When combined with even deeper, public broadband data...
The newly installed Wide Field Camera 3 (WFC3) on the Hubble Space Telescope has been used to obtain multi-band images of nearby spiral galaxy M83. These new observations are deepest and highest resolution ever taken a grand-design spiral, particularly in near-ultraviolet, allow us better differentiate compact star clusters from individual stars measure luminosities even faint U band. We find that luminosity function (LF) for outside very crowded starburst nucleus can be approximated by...
We use new WFC3 observations of the nearby grand design spiral galaxy M83 to develop two independent methods for estimating ages young star clusters. The first method uses physical extent and morphology Halpha emission estimate clusters younger than tau ~10 Myr. It is based on simple premise that gas in very (tau < few Myr) largely coincident with cluster stars, a small, ring-like structure surrounding stars slightly older (e.g., ~5 Myr), larger bubble still (i.e., ~5-10 Myr). second an...
We present a study correlating the spatial locations of young star clusters with those molecular clouds in NGC~5194, order to investigate timescale over which separate from their birth clouds. The cluster catalogues are Legacy ExtraGalactic UV Survey (LEGUS) and Plateau de Bure Interefrometer Arcsecond Whirpool (PAWS). find that younger spatially closer than older clusters. median ages for associated is 4~Myr whereas it 50~Myr sufficiently separated cloud be considered unassociated. After...
We present a study of the effective (half-light) radii and other structural properties systematically selected sample young, massive star clusters (YMCs, $\geq$$5\times10^3$ M$_{\odot}$ $\leq$200 Myr) in two nearby spiral galaxies, NGC 628 1313. use Hubble Space Telescope WFC3/UVIS archival ACS/WFC data obtained by Legacy Extragalactic UV Survey (LEGUS), an HST Treasury Program. measure with GALFIT, two-dimensional image-fitting package, new technique to estimate from concentration index...
Abstract We present a study of the hierarchical clustering young stellar clusters in six local (3–15 Mpc) star-forming galaxies using Hubble Space Telescope broadband WFC3/UVIS UV and optical images from Treasury Program LEGUS (Legacy ExtraGalactic Survey). identified 3685 likely associations, each visually classified by their morphology, we use angular two-point correlation function to these systems. find that spatial distribution associations are clustered with respect other, forming...
We present a study of the spatial distribution stellar cluster populations in star-forming galaxy NGC 628. Using Hubble Space Telescope broadband WFC3/UVIS UV and optical images from Treasury Program LEGUS (Legacy ExtraGalactic Survey), we have identified 1392 potential young ( Myr) clusters within using combination visual inspection automatic selection. investigate clustering these quantify strength change with scale two-point correlation function. also how image boundary conditions dust...
We present the star cluster catalogs for 17 dwarf and irregular galaxies in $HST$ Treasury Program "Legacy ExtraGalactic UV Survey" (LEGUS). Cluster identification photometry this subsample are similar to that of entire LEGUS sample, but special methods were developed provide robust with accurate fluxes due low statistics. The colors ages largely consistent two widely used aperture corrections, a significant fraction clusters more compact than average training cluster. However, ensemble...
Abstract The earliest stages of star formation occur enshrouded in dust and are not observable the optical. Here we leverage extraordinary new high-resolution infrared imaging from JWST to begin study dust-embedded clusters nearby galaxies throughout Local Volume. We present a technique for identifying NGC 7496 (18.7 Mpc), first galaxy be observed by PHANGS–JWST Cycle 1 Treasury Survey. select sources that have strong 3.3 μ m PAH emission based on F300M − F335M color excess identify 67...
Abstract We present the largest catalog to date of star clusters and compact associations in nearby galaxies. have performed a V -band-selected census across 38 spiral galaxies PHANGS–Hubble Space Telescope (HST) Treasury Survey, measured integrated, aperture-corrected near-ultraviolet- U-B-V-I photometry. This work has resulted uniform catalogs that contain ∼20,000 associations, which passed human inspection morphological classification, larger sample ∼100,000 classified by neural network...
The production rate of ionizing photons in young < 8 Myr, unresolved stellar clusters the nearby irregular galaxy NGC 4214 is probed using multi-wavelength Hubble Space Telescope WFC3 data. We normalize photon by cluster mass to investigate upper end initial function (IMF). have found that within uncertainties IMF appears be universal this galaxy, and deviations from a can attributed stochastic sampling stars with masses 10^3 M_sun. Furthermore, we there does not seem dependence maximum on...
The nearby dwarf starburst galaxy NGC 5253 hosts a number of young, massive star clusters, the two youngest which are centrally concentrated and surrounded by thermal radio emission (the "radio nebula"). To investigate role these clusters in energetics, we combine new archival Hubble Space Telescope images with wavelength coverage from 1500 Å to 1.9 μm 13 filters. These include Hα, Pβ, Pα, imaging Treasury Program LEGUS (Legacy Extragalactic UV Survey). extraordinarily well-sampled spectral...
Recently acquired WFC3 UV (F275W and F336W) imaging mosaics under the Legacy Extragalactic Survey (LEGUS) combined with archival ACS data of M51 are used to study young star cluster (YSC) population this interacting system. Our newly extracted source catalogue contains 2834 candidates, morphologically classified be compact uniform in colour, for which ages, masses extinction derived. In first work we main properties YSC whole galaxy, considering a mass-limited sample. Both luminosity mass...
The morphology of HII regions around young star clusters provides insight into the timescales and physical processes that clear a cluster's natal gas. We study ~700 (<10Myr) in three nearby spiral galaxies (NGC 7793, NGC 4395, 1313) using Hubble Space Telescope (HST) imaging from LEGUS (Legacy ExtraGalactic Ultraviolet Survey). Clusters are classified by their H$\alpha$ (concentrated, partially exposed, no-emission) whether they have neighboring (which could affect clearing timescales)....
The Immersion Grating Infrared Spectrometer (IGRINS) is a revolutionary instrument that exploits broad spectral coverage at high-resolution in the near-infrared. IGRINS employs silicon immersion grating as primary disperser, and volume-phase holographic gratings cross-disperse H K bands onto Teledyne Hawaii-2RG arrays. use of an facilitates compact cryostat while providing simultaneous wavelength from 1.45 - 2.5 μm. There are no cryogenic mechanisms its high-throughput design maximizes...
The Immersion GRating INfrared Spectrometer (IGRINS) was designed for high-throughput with the expectation of being a visitor instrument at progressively larger observing facilities. IGRINS achieves R∼45000 and > 20,000 resolution elements spanning H K bands (1.45-2.5μm) by employing silicon immersion grating as primary disperser volume-phase holographic gratings cross-dispersers. After commissioning on 2.7 meter Harlan J. Smith Telescope McDonald Observatory, had more than 350 scheduled...
We present an analysis of the positions and ages young star clusters in eight local galaxies to investigate connection between age difference separation cluster pairs. find that do not form uniformly but instead are distributed such increases with pair 0.25-0.6 power, maximum size over which formation is physically correlated ranges from ~200 pc ~1 kpc. The observed trends suggest hierarchical both space time: close each other more similar than born further apart. temporal correlations...
We investigate a novel Bayesian analysis method, based on the Stochastically Lighting Up Galaxies (slug) code, to derive masses, ages, and extinctions of star clusters from integrated light photometry. Unlike many methods, slug correctly accounts for incomplete initial mass function (IMF) sampling, returns full posterior probability distributions rather than simply maxima. apply our technique 621 visually confirmed in two nearby galaxies, NGC 628 7793, that are part Legacy Extragalactic UV...