• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.42.2-42.2
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• 2014

We investigate the history of formation of ~400 galaxies in four Abell clusters at 0.04

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.142.1-142.1
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• 2011

UBVI and $H{\alpha}$ CCD photometry of IC 1848, one of active star-forming regions in Cas OB6, is carried out as a part of Sejong Open cluster Survey (SOS) project. An OB association is an ideal laboratory for studying the triggered star formation and star formation history. Our purposes are to provide deep photometric data up to 21 mag in V and physical parameters of IC 1848. We classify 79 early-type stars and 186 pre-main sequence (PMS) stars as being the members of the cluster using photometric criteria. The IR excess emission PMS stars by Koenig et al. (2008) are also included as members of IC 1848. Total number of members is 414. We derive the interstellar reddening (=$0.659{\pm}0.058$ mag), reddening law ($R_V=4.0{\pm}0.1$), distance modulus ($V_0-M_V=12.0{\pm}0.1$ mag) using the early-type members of IC 1848. We also determine the age of the cluster ($3.5{\pm}1.5$ Myr) by placing the theoretical isochrones on the HR diagram.

• Journal of The Korean Astronomical Society
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• v.38 no.3
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• pp.345-355
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• 2005

We present a photometric study of the star cluster system in the merging galaxy NGC 1487, based on the BI photometry obtained from the F450W and F814W images in the HST /WFPC2 archive data. We have found about 560 star cluster candidates in NGC 1487, using the morphological parameters of the objects. We have investigated several photometric characteristics of the clusters: color-magnitude diagrams (CMDs), color distribution, spatial distribution, age, size and luminosity function. The CMD of the bright clusters with 18.5 < B < 24 mag in NGC 1487 shows three major populations of clusters: a blue cluster population with $(B-I){\le}0.45$, an intermediate-color cluster population with $0.45<(B-I){\le}1.55$, and a red cluster population with (B - I) > 1.55. The intermediate-color population is the most dominant among the three populations. The brightest clusters in the blue and intermediate- color populations are as bright as $B{\approx}18mag$ ($M_B{\approx}-12mag$), which are three magnitudes brighter than those in the red population. The blue and intermediate-color clusters are strongly concentrated on the bright condensations, while the red clusters are relatively more scattered over the galaxy. The CMD of these clusters is found to be remarkably similar to that of the clusters in the famous interacting system M51. From this we suggest that the intermediate-color clusters were, probably, formed during the merging process which occurred about 500 Myrs ago.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.293-297
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• 2017

We discuss a new IRAS Faint Source Catalog galaxy redshift catalogue (RIFSCz) which incorporates data from Galex, SDSS, 2MASS, WISE, AKARI and Planck. AKARI fluxes are consistent with photometry from other far infrared and submillimetre missions provided an aperture correction is applied. Results from the Hermes-SWIRE survey in Lockman are also discussed briefly, and the strong contrast between the galaxy populations selected at 60 and $500{\mu}m$ is summarized.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.84.2-84.2
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• 2014

We report the discovery of a new Milky Way globular cluster (GC) candidate in the Galactic plane. We found this object during our WISE survey of star clusters in the Milky Way. We derived physical parameters of this object using the 2MASS JHK photometry. The color-magnitude diagram of the resolved stars shows a well-developed red giant branch (RGB). We derived its reddening, distance and metallicity. These results indicate that it is probably an old globular cluster, located behind the Galactic disk.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.243-243
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• 1996

UBV observations have been made jointly at three observatories for the recent eclipse of the long period atmospheric eclipsing binary star Zeta Aur in 1995-6. Observations covered successfully the phases before, during, and after the eclipse enable us to determine the accurate time of mid-eclipse and the duration of the totality. The hypothesis of the expansion of the K supergiant has been tested and the positive conclusion may be derived.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.85.3-85.3
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• 2019

Pulsating variable is a star whose luminosity changes through periodic pulsation. There are radiative and dynamical mechanisms hidden in periodic brightness changes, and the physical quantities related with the mechanisms are also expected to vary periodically. The purpose of this study is to investigate the periodic variations of the physical quantities of the ${\delta}$ Scuti type variable, V350 Peg by simultaneous photometry and spectroscopy. In this poster, we present preliminary results on apparent magnitude and radial velocity at the surface.

• Journal of The Korean Astronomical Society
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• v.44 no.1
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• pp.1-11
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• 2011

A sample of 145 JHK-2MASS observations of NGC open star clusters is studied, of which 132 have never been studied before. Twelve are classified as non-open clusters and 13 are re-estimated self-consistently, after applying the same methods in order to compare and calibrate our reduction procedures. The fundamental and structural parameters of the 120 new open clusters studied here are derived using color-magnitude diagrams of JHK Near-IR photometry with the fitting of solar metallicity isochrones. We provide here, for the first time, a catalog of the main parameters for these 120 open clusters, namely, diameter, distance, reddening and age.

• Publications of The Korean Astronomical Society
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• v.19 no.1
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• pp.33-37
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• 2004

Through time-series CCD photometry using a 130mm refractor of Busan Science Academy, we found a new $\delta$ Scuti type variable star, esc 03665-00576. We performed following observations using a 1.8m telescope of Bohyunsan Optical Astronomy Observatory. Three frequencies have been derived by multiple-frequency analysis, which are 10.968, 7.156 and 15.182cycle $day^{-1}$, respectively. V-amplitude of esc 03665-00576 is ${\Delta}V$= 0.04.

• Journal of The Korean Astronomical Society
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• v.42 no.2
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• pp.17-26
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• 2009

We estimate the enclosed mass profile in the central 10 pc of the Milky Way by analyzing the infrared photometry and the velocity observations of dynamically relaxed stellar population in the Galactic center. HST/NICMOS and Gemini Adaptive Optics images in the archive are used to obtain the number density profile, and proper motion and radial velocity data were compiled from the literature to find the velocity dispersion profile assuming a spherical symmetry and velocity isotropy. From these data, we calculate the the enclosed mass and density profiles in the central 10 pc of the Galaxy using the Jeans equation. Our improved estimates can better describe the exact evolution of the molecular clouds and star clusters falling down to the Galactic center, and constrain the star formation history of the inner part of the Galaxy.