• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.30.2-30.2
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• 2016

M104 (NGC 4594, the Sombrero) is an intriguing disk galaxy classified as an elliptical galaxy nowadays. It hosts a luminous bulge and a massive disk, but it is still mysterious how M104 acquired such peculiar structures. Globular clusters are an useful tracer to investigate the formation history of early-type galaxies. In this study we present a wide field imaging study of the globular clusters in M104. Using wide ($1^{\circ}{\times}1^{\circ}$) and deep ugi images of M104 obtained with the CFHT/MegaCam observations, we detect a large number of globular clusters. The color distribution of these globular clusters shows that there are two subpopulations: a metal-poor system and a metal-rich system. The radial number density of the metal-poor globular clusters shows a long tail reaching R ~ 30' (~ 80 kpc), indicating clearly the existence of a giant metal-poor halo in M104. This result is consistent with the previous studies on the dual halos of massive early-type galaxies. We will discuss implications of these results in relation with the formation history of M104.

• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.179-193
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• 1997

We use B band CCD images to investigate the surface brightness distributions and dynamical properties of 29 Galactic globular clusters. Model fits suggest that 22 clusters show King type surface brightness profiles, while 7 clusters are characterized by power law cusp profiles. For the King type clusters, concentration parameters $(c=log(r_{t}/r_{c}))$ range from 1.20 to 2.10, and core radii are 0.4 to 1.9 pc. The mean value of power law slopes of 7 cuspy clusters was estimated as ${alpha}=1.011{\pm}0.065$. Total masses of King type globular clusters are in the range of $1.7{ imes}10^4M_{odot}$ to $1.0{\times}106M_{\odot}$ with a mean of $1.7{\times}10^5M_{\odot}$. A significant positive correlation between mass and mass-to-light ratio of King type globular clusters has been confirmed with a Pearson's correlation coefficient r = 0.52 and a confidence level of 99%. Our data also confirm a linear relation between total mass and absolute magnitude of King type globular clusters.

• Genomics & Informatics
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• v.9 no.2
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• pp.74-78
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• 2011

Numerous restraints and simplifications have been developed for methods that anticipate protein structure to reduce the colossal magnitude of possible conformational states. In this study, we investigated if globularity is a general characteristic of proteins and whether they can be applied as a valid constraint in protein structure simulations with approximated measurements (Gb-index). Unexpectedly, most of the proteins showed strong structural globularity (i.e., mode of approximately 76% similarity to the perfect globe) with only a few percent of proteins being outliers. Small proteins tended to be significantly non-globular ($R^2$=0.79) and the minimum Gb-index showed a logarithmic increase with the increase in protein size ($R^2$=0.62), strongly implying that the non-globular characteristics might be more acceptable for smaller proteins than larger ones. The strong perfect globe-like character and the relationship between small size and the loss of globular structure of a protein may imply that living organisms have mechanisms to aid folding into the globular structure to reduce irreversible aggregation. This also implies the possible mechanisms of diseases caused by protein aggregation, including some forms of trinucleotide repeat expansion-mediated diseases.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.68.2-68.2
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• 2012

We present a discovery of two new globular clusters in the Hubble Space Telescope archive images of the M81 group. They are located much farther from both M81 and M82 in the sky, compared with previously known star clusters in these galaxies. Both clusters show that higher luminosity and larger effective radius than typical globular clusters in Milky Way and M81. Using the available spectroscopic data provided by the Sloan Digital Sky Survey, we derive a low metallicity with [Fe/H] ${\approx}$ -2.3 and an old age ~14 Gyr for GC-2. The I-band magnitude of the tip of the RGB for GC-1 is consistent with that of the halo stars in the GC-1 and GC-2 field. However, that of GC-2 is 0.26 mag fainter than its field. It shows that GC-2 is about 400 kpc behind the M81 halo along our line of sight. The deprojected distance to GC-2 from M81 is much larger than any other known globular clusters in the local universe. We discuss the possible scenarios to explain the existence of globular cluster in such an extremely isolated environment.

• Publications of The Korean Astronomical Society
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• v.1 no.1
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• pp.9-12
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• 1984

Using King's model, we derived the dynamical masses of six globular clusters. The masses of clusters were calculated from the dynamical length parameters combined with the central velocity dispersion. The dynamical masses are all in the range from $2.5{\times}10^{5}M_{\odot}$ to $1.4{\times}10^{5}M_{\odot}$. The $(M/L_v)_{\odot}$, values lie between 1.0 and 1.2, which are typical for galactic clusters.

• Journal of Astronomy and Space Sciences
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• v.11 no.2
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• pp.147-153
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• 1994

We present a deep(B, V) color-magnitude diagram (CMD) of the Galactic globular cluster NGC 4372. According to the recent inside-out picture of Galaxy formation, this cluster is predicted to be one of the oldest globulat clusters in the Galaxy. Our CMD shows a well defined main-sequence extending ∼ 2 magnitudes below the trunoff. Despite the uncertainty that stems from the small sample size of bright stars, comparison with the Revised Yale Isochrones suggests that this cluster may indeed be one of the oldest (∼16.6 Gyrs) globular clusters in our Galaxy.

• 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.13 no.1
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• pp.27-33
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• 1980

Surface density distributions for globular clusters were obtained from photoelectric surface photometry (using centered aperture photometry). These surface brightness profiles were then compared with the theoretical surface density distribution of King's model. From the comparison of the theoretical and observed surface density distributions, we determine he structural parameters of the clusters (the core radius $r_c$, the tidal cut off $r_t$, and the concentration factor C).

• Bulletin of the Korean Space Science Society
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• 1993.10a
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• pp.19-19
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• 1993

We have developed a new method to simulate the observed color magnitudediagrams for Galactic globular clusters. The model calculations include all evolutionary phases- from zero age main sequence to asymptotic giant branch. Using these models, we can simulate directly the observational errors and sampling effect and also can examine the stellar evolution theory in more$.$ realistic way. Implications of these model calculations on the recent space observations of globular clusters and other systems will be discussed.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.137-138
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• 1996

The first large-format CCD color-magnitude diagram (CMD) in the B and V passbands is presented for the Galactic globular cluster M53 (NGC 5024). We have discovered 117 new blue straggler (BS) candidates in the field of M53. The analysis of bright BS stars (V <19.0) clearly shows a bimodal radial distribution, with a high frequency in the inner and outer regions. The distribution is similar to that found in M3, a globular cluster with similar central density and concentration.