• 한국지구과학회지
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• 제38권5호
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• pp.333-344
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• 2017

We present the environmental dependence of the luminosity-size relation of galaxies in the local universe (z < 0.01) along with their dependence on galaxy morphology represented by five broad types (E, dEs, S0, Sp, and Irr). The environmental parameters we consider are the local background density and the group/cluster membership together with the clustercenteric distance for the Virgo cluster galaxies. We derive the regression coefficient (${\beta}$), i.e., the slope of the line representing the least-squares fitting to the data and the Pearson correlation coefficient (c.c.) representing the goodness of the least-squares fit along with the confidence interval from bootstrap resampling. We find no significant dependence of the luminosity-size relation on galaxy morphology. However, there is a weak dependence of the luminosity-size relations on the environment of galaxies, in the sense that galaxies in the low density environment have shallower slopes than galaxies in the high density regions except for elliptical galaxies that show an opposite trend.

• 천문학회보
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• 제40권1호
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• pp.76.1-76.1
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• 2015

We study the environmental dependence of the mass-size relation especially for the most massive early type galaxies (M>$10^{11.2}M_{\odot}$) in the redshift range 0.15~0.25. As a measure of the environment, galaxy number densities are measured by the $10^{th}$ nearest galaxies within 7000km/s from galaxies with spectroscopic redshifts. We find that galaxies more massive than $10^{11.6}M_{\odot}$ show the environmental dependence in the mass-size relation. The galaxies with M>$10^{11.6}M_{\odot}$ located in the densest, cluster like environment have larger sizes than their counterparts located in a low dense environment. We also find that this environmental dependence of the mass-size relation originates from the brightest cluster galaxies (BCG) rather than non-BCG galaxies. Our result can be explained with a hierarchical growth of the most massive galaxies through dissipation-less merger in dense environments.

• 천문학회보
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• 제40권2호
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• pp.29.1-29.1
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• 2015

We study the environmental dependence of the mass-size relation for the most massive early type galaxies (M > $10^{10.7}M_{\odot}$) in the redshift range 0.10~0.15. As a measure of the environment, galaxy number densities are measured by the $10^{th}$ nearest galaxies within 6500km/s from galaxies with spectroscopic redshifts. The sizes of galaxies are measured by non-parametric method. We find that galaxies more massive than $10^{11.1}M_{\odot}$ show the environmental dependence in the mass-size relation. The galaxies with M > $10^{11.1}M_{\odot}$ located in the densest, cluster like environment have larger sizes and extended surface brightness profiles than their counterparts located in a low dense environment. We also find that the environmental dependence of the mass-size relation is more significant for the brightest cluster galaxies (BCGs) than non-BCGs. Our result can be explained with a hierarchical growth of the most massive galaxies through dissipation-less merger in dense environment.

• 천문학회보
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• 제41권1호
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• pp.69.2-69.2
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• 2016

We study the environmental dependence of the mass-size relation for the most massive early type galaxies (M>$10^{10.7}M_{\odot}$) in the redshift range 0.10~0.15. The sizes of galaxies are measured by non-parametric method. We find that galaxies more massive than $10^{11.1}M_{\odot}$ show the environmental dependence in the mass-size relation. The galaxies with M>$10^{11.1}M_{\odot}$ located in the densest, cluster like environment have larger sizes and extended surface brightness profiles than their counterparts located in a low dense environment. We also find that the environmental dependence of the mass-size relation is more significant for the brightest cluster galaxies (BCGs) than non-BCGs. We use the semi analytic galaxy formation simulation based on the Millennium 1 Simulation for interpretation. Our result can be explained with a hierarchical growth of the most massive galaxies through dissipation-less merger in dense environment.

• 천문학회보
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• 제36권2호
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• pp.77.1-77.1
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• 2011

The sizes of galaxies are correlated with their masses or luminosities, which is known as the 'mass-size relation' or 'luminosity-size relation'. Those relations show scatters in the sense that the sizes of galaxies range somewhat widely at given mass or luminosity, which is largely affected by the morphologies or colors of the sample galaxies. However, the scatters of the relations are still large even when the galaxy sample is limited to red early-type galaxies: at fixed mass or luminosity, the largest red early-type galaxies are larger than the smallest red early-type galaxies by a factor of 4 - 5. This is a progress report of a study on what determines the sizes of red early-type galaxies. We investigate how the sizes of red early-type galaxies depend on several quantities of them, such as color, color gradient, axis ratio, local number density and mass-to-light ratio. The physical implication of those preliminary results is discussed.

• 천문학회보
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• 제42권1호
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• pp.30.1-30.1
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• 2017

In the hope to detect low-surface brightness features (${\mu}_{r^{\prime}}{\sim}27\;mag\;arcsec^{-2}$), we carried out KASI-Yonsei Deep Imaging Survey for Clusters (KYDISC) targeting 14 local clusters at 0.016 < z < 0.145 using Magellan/IMACS telescope and CFHT/MegaCam. Out of 1450 cluster galaxies, 18% of galaxies show the signatures of galaxy mergers. We explore merger-driven changes from various point-of-view. We first examine color-magnitude relations, and find that galaxies related to recent mergers are populated more on blue color than their counterparts. Besides, we find the extremely low frequency of mergers on low-mass red-sequence galaxies, suggesting a migration of red galaxies into the green-valley region through merger-driven star-formation. We also study the mass-size relation of our sample, finding a larger galaxy size in galaxies related to recent mergers. Our results suggest that mergers can simultaneously change properties of galaxies, making outliers on galactic scaling relations.

• 천문학회보
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• 제40권2호
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• pp.48.3-49
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• 2015

Scaling relations of early-type galaxies (ETG) provide a deep insight into their formation and evolution. Interestingly enough, most relations extending into the dwarf regimes display non-linear or broken-linear features, unlike the linear relations for normal (i.e., intermediate-mass to giant) ETGs only. Here we investigate the mass-size scaling relation of ETGs using a massive database of galaxies from SDSS DR12. We divide ETGs into two groups by the indication of star formation such as colors, and examine their distinction along the mass-size relation. We find that the mass-size distribution of blue, young normal galaxies is in good agreement with that of dwarf ETGs. Our result suggests that blue, young normal ETGs may serve as links between (passive) normal ETGs and dwarfs. We discuss the possibility of blue, young ETGs being progenitors of dwarf ETGs.

• 천문학회보
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• 제39권2호
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• pp.66.2-66.2
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• 2014

The size evolution of galaxies is one of the fascinating issues in these days. It is known that the size of a galaxy is closely related to other galactic properties, such as the central surface brightness, stellar mass, and redshift. However, we need to measure the sizes of galaxies precisely to understand those relations. We determine the sizes of early-type galaxies in the nearby clusters (z<0.2) using the GALAPAGOS. The GALAPAGOS is a tool which provides surface photometry for multiple sources, which make it fast and convenient to deal with huge image data. We run the GALAPAGOS individually to the Subaru/Suprime-Cam and the HST/ACS images for the same targets. We present and discuss the result of our size measurements for further applications.

• 천문학회지
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• 제19권2호
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• pp.69-89
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• 1986

The global morphology and geometric parameters of 39 barred galaxies are investigated, by using isophote map and isodensity tracings obtained from detailed surface photometry with the Kiso V-band plates. The observed results are as follows: i) There is no strong indication that the ratio of bar length to disk size is correlated with Hubble type, except that the largest bars appear in the SBb galaxies. ii) The mean value of axial ratios of bars is $2.0{\pm}0.4$ and there is a trend that early type galaxies have smaller axial ratios than late type galaxies. iii) About 15% of early type barred galaxies(Sb0-SBb) have triaxial bulges.

• 천문학회지
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• 제32권2호
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• pp.75-82
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• 1999

Diffuse radio emission in Abell 2256 was detected above 3 $\sigma$ with DRAO observations at 1420 MHz. The halo size is $\~13' {\times}10' (\~1h^{-1}_{50}\;Mpc$) in full extent and is elongated along a position angle of about $112^{\circ}$. The total flux density contained in the halo is 30$\pm$10 mJy at 1420 MHz and its spectral index is -2.04$\pm$0.04, showing no evidence for steepening up to 1420 MHz. Using the size estimate, yields a more reliable equipartition magnetic field strength which is $0.34(1 + k)^{2/7}{\mu}G$. In addition, five new radio sources are identified.