COS^2MIC

Database of YEPS (Yonsei Evolutionary Population Synthesis)

Model for Simple Stellar Populations

Table 1. The YEPS photometric evolution model (Version 1.0) for simple stellar populations. (Chung et al. 2017)

Johnson (U, B, V, R, I, J, H, Ks, L, M), Washington (C, M, T1, T2), SDSS (u, g, r, i, z), HST/WFPC2 (f336w, f547m, f555w, f606w, f814w, f850lp), HST/ACS (f475w, f555w, f606w, f814w, f850lp), HST/WFPC3 (f336w, f465w, f547m, f555w, f606w, f814w, f850lp) magnitudes are available as functions of metallicity and age (1.0 < t < 15.0 Gyr by 1.0 Gyr).

YEPS Models	[alpha/Fe]
YEPS Models	0.0 (-2.5 < [Fe/H] < 0.5 by 0.1 dex)	0.3 (-2.5 < [Fe/H] < 0.5 by 0.1 dex)	0.6 (-2.5 < [Fe/H] < 0.3 by 0.1 dex)
Standard Model	AB Mag System ST Mag System Vega Mag System	AB Mag System ST Mag System Vega Mag System	AB Mag System ST Mag System Vega Mag System
Models without Horizontal Branches	AB Mag System ST Mag System Vega Mag System	AB Mag System ST Mag System Vega Mag System	AB Mag System ST Mag System Vega Mag System

Table 2. The YEPS spectroscopic evolution model (Version 1.0) for simple stellar populations. (Chung et al. 2013)

LICK absorption line indices (metal indices - CN1, CN2, Ca4227, G4300, Fe4383, Ca4455, Fe4531, C_2 4668, Fe5015, Mg1, Mg2, Mgb, Fe5270, Fe5335, Fe5406, Fe5709, Fe5782, NaD, TiO1, TiO2 and Balmer indices - H_beta, H_gamma A, H_gamma F, H_delta A, H_delta F) are available as functions of metallicity and age (1.0 < t < 15.0 Gyr by 1.0 Gyr).

YEPS Models	[alpha/Fe]
YEPS Models	0.0 (-2.5 < [Fe/H] < 0.5 by 0.1 dex)	0.3 (-2.5 < [Fe/H] < 0.5 by 0.1 dex)	0.6 (-2.5 < [Fe/H] < 0.3 by 0.1 dex)
Standard Model	Based on the Line Fitting Function from Worthey et al. 1994, 97 Schiavon et al. 2007 Johansson et al. 2010	Based on the Line Fitting Function from Worthey et al. 1994, 97 Schiavon et al. 2007 Johansson et al. 2010	Based on the Line Fitting Function from Worthey et al. 1994, 97 Johansson et al. 2010
Models without Horizontal Branches	Based on the Line Fitting Function from Worthey et al. 1994, 97 Schiavon et al. 2007 Johansson et al. 2010>	Based on the Line Fitting Function from Worthey et al. 1994, 97 Schiavon et al. 2007 Johansson et al. 2010	Based on the Line Fitting Function from Worthey et al. 1994, 97 Johansson et al. 2010

Table 3. Model ingredients and input parameters.

Ingredients	Stellar and Flux Libraries
MS to RGB evolutionary tracks	Kim et al. (2002) Yonsei-Yale Version 2 Isochrones
MS to RGB evolutionary tracks	Yi et al. (2008) Yonsei-Yale Version 3 Isochrones
Post-RGB evolutionary tracks	Han et al. (2009) Yonsei-Yale HB tracks
Flux Libraries	Lejeune et al. (1998) model atmosphere
Flux Libraries	Westera et al. (2003) model atmosphere
Absorption Line Fitting Functions	Worthey et al. (1994, 1997)
	Schiavon (2007)
	Johansson et al. (2010)
α-element response function	Korn et al. (2005)
Input Parameters	The used values
Initial Mass Function	Salpeter (x=1.35)
Total star mass	10^7 solar mass (photometric evolution model) 10^6 solar mass (spectroscopic evolution model)
α-element enhancement, [α/Fe]	0.0, 0.3, 0.6 dex
Mass loss formula	Reimers’ (1975) mass-loss efficiency parameter, η=0.63
HB mass dispersion	0.015 Solar Mass

Table 4. The YEPS photometric evolution model for helium enhanced stellar populations. (Chung et al. 2017)

YEPS model	Y_ini
YEPS model	0.23	0.28	0.33	0.38	0.43
Eta = 0.5 model	AB Mag System ST Mag System Vega Mag System	AB Mag System ST Mag System Vega Mag System	AB Mag System ST Mag System Vega Mag System	AB Mag System ST Mag System Vega Mag System	AB Mag System ST Mag System Vega Mag System

Table 5. The YEPS spectroscopic evolution model for helium enhanced stellar populations. (Chung et al. 2017)

YEPS model	Y_ini
YEPS model	0.23	0.28	0.33	0.38	0.43
Eta = 0.5 model	Worthey et al. 1994, 97	Worthey et al. 1994, 97	Worthey et al. 1994, 97	Worthey et al. 1994, 97	Worthey et al. 1994, 97

Table 6. The YEPS surface brightness fluctuation model for helium enhanced stellar populations. (Chung et al. 2020)

YEPS SBF Models	Y_ini
YEPS SBF Models	0.23	0.28	0.33
Eta=0.5 model	AB Mag System ST Mag System Vega Mag System	AB Mag System ST Mag System Vega Mag System	AB Mag System ST Mag System Vega Mag System

Refereed Papers that Have Used the YEPS Models

Chung, C., Yoon, S.-J., Cho, H., Lee, S.-Y., Lee, Y.-W. (2020), Accepted for publication in ApJS "Yonsei Evolutionary Population Synthesis (YEPS) Model. III. Surface Brightness Fluctuation of Normal and Helium-enhanced Simple Stellar Populations"

Kang, Y., Lee, Y.-W., Kim, Y.-L., Chung, C., Ree, C. H. (2020), ApJ, 889, 8 "Early-type Host Galaxies of Type Ia Supernovae. II. Evidence for Luminosity Evolution in Supernova Cosmology"

Chung, C., Pasquato, M., Lee, S.-Y.,di Carlo, U. N., An, D., Yoon, S.-J., Lee, Y.-W., (2019), ApJL, 883L, 31, "Radial Dependence of the Proto-globular Cluster Contribution to the Milky Way Formation"

An, D., Pinsonneault, M. H., Terndrup, D. M., Chung, C., (2019), ApJ, 879, 81, "Comparison of the Asteroseismic Mass Scale of Red Clump Giants with Photometric Mass Estimates"

Lee, S.-Y., Chung, C., Yoon, S.-J., (2019), ApJS, 240, 2, "Nonlinear Color-Metallicity Relations of Globular Clusters. VIII. Reproducing Color Distributions of Individual Globular Cluster Systems in the Virgo and Fornax Galaxy Clusters"

Kim, Sooyoung; Yoon, Suk-Jin (2017), ApJ, 843, 43 "Nonlinear Color-Metallicity Relations of Globular Clusters. VII. Nonlinear Absorption-line Index versus Metallicity Relations and Bimodal Index Distributions of NGC 5128 Globular Clusters"

Subramaniam, A., Sahu, S., Postma, J. E., C^ote, P., Hutchings, J. B., Darukhanawalla, N., Chung, C., Tandon, S. N., Kameswara Rao, N., George, K., Ghosh, S. K., Girish, V., Mohan, R., Murthy, J., Pati, A. K., Sankarasubramanian, K., Stalin, C. S., Choudhury, S., (2017), AJ, 154, 233, "The Horizontal Branch Population of NGC 1851 as Revealed by the Ultraviolet Imaging Telescope (UVIT)"

Chung, Chul; Yoon, Suk-Jin; Lee, Young-Wook (2017), ApJ, 842, 91 "Yonsei evolutionary population synthesis (YEPS). II. Spectro-photometric evolution of helium-enhanceed stellar populations:

Chung, Chul; Yoon, Suk-Jin; Lee, Sang-Yoon; Lee, Young-Wook (2016), ApJ, 818, 201 "Nonlinear Color-Metallicity Relations of Globular Clusters. VI. On Calcium II Triplet Based Metallicities of Globular Clusters in Early-type Galaxies"

Kim, Hak-Sub; Cho, Jaeil; Sharples, Ray M.; Vazdekis, Alexandre; Beasley, Michael A; Yoon, Suk-Jin (2016), ApJS, 227, 24 "A New Catalog of Homogenized Absorption Line Indices for Milky Way Globular Clusters from High-resolution Integrated Spectroscopy"

Yoon, Suk-Jin; Sohn, Sangmo T.; Kim, Hak-Sub; Chung, Chul; Cho, Jaeil; Lee, Sang-Yoon; Blakeslee, John P. (2013), ApJ, 768, 137 "Nonlinear Color-Metallicity Relations of Globular Clusters. IV. Testing the Nonlinearity Scenario for Color Bimodality via HST/WFC3 u-band Photometry of M84 (NGC 4374)"

Kim, Sooyoung; Yoon, Suk-Jin; Chung, Chul; Caldwell, Nelson; Schiavon, Ricardo P.; Kang, Yongbeom; Rey, Soo-Chang; Lee, Young-Wook (2013), ApJ, 768, 138 "Nonlinear Color-Metallicity Relations of Globular Clusters. V. Nonlinear Absorption-line Index versus Metallicity Relations and Bimodal Index Distributions of M31 Globular Clusters"

Chung, Chul; Lee, Sang-Yoon; Yoon, Suk-Jin; Lee, Young-Wook (2013), ApJL, 769L, 3 "The effect of second generation populations on the integrated colors of metal-rich globular clusters in early-type galaxies"

Kim, Hak-Sub; Yoon, Suk-Jin; Sohn, Sangmo Tony; Kim, Sang Chul; Kim, Eunhyeuk; Chung, Chul; Lee, Sang-Yoon; Lee, Young-Wook (2013), ApJ, 763, 40 "Wide-field Multiband Photometry of Globular Cluster Systems in the Fornax Galaxy Cluster"

Chung, Chul; Yoon, Suk-Jin; Lee, Sang-Yoon; Lee, Young-Wook (2013), ApJS, 204, 3 "Yonsei Evolutionary Population Synthesis (YEPS) Model. I. Spectroscopic Evolution of Simple Stellar Populations"

Ree, Chang H.; Jeong, Hyunjin; Oh, Kyuseok; Chung, Chul; Lee, Joon Hyeop; Kim, Sang Chul; Kyeong, Jaemann (2012) ApJL, 774L, 10 "Ultraviolet Color-Color Relation of Early-type Galaxies at 0.05 < z < 0.12"

J. Cho, R.M. Sharples, J.P. Blakeslee, S.E. Zepf, A. Kundu, H.-S. Kim, S.-J. Yoon (2012) MNRAS, 422, 3591 "Globular cluster systems of early-type galaxies in low-density environments"

Suk-Jin Yoon, Sangmo Sohn, Sang-Yoon Lee, Hak Sub Kim, Jaeil Cho, Chul Chung, and John P. Blakeslee (2011) ApJ, 743, 149 "Nonlinear Color-Metallicity Relations of Globular Clusters. II. A Test on the Nonlinearity Scenario for Color Bimodality Using the u-band Colors: The Case of M87 (NGC 4486)"

Suk-Jin Yoon, Sang-Yoon Lee, John P. Blakeslee, Eric W. Peng, Sangmo Sohn, Jaeil Cho, Hak Sub Kim, Chul Chung, Sooyoung Kim, and Young-Wook Lee (2011) ApJ, 743, 150 "Nonlinear Color-Metallicity Relations of Globular Clusters. III. On the Discrepancy in Metallicity between Globular Cluster Systems and their Parent Elliptical Galaxies"

C. Chung, S.-J. Yoon, and Y.-W. Lee (2011) ApJ, 740, L45 "The Effect of Helium-enhanced Stellar Populations on the UV-upturn Phenomenon of Early-type Galaxies"

Rey S.-C.; Yoon, S.-J. et al. (2009) ApJ, 700, 11 "Probing the Intermediate-Age Globular Clusters in NGC 5128 from Ultraviolet Observations"

Choi, Y.; Goto, T. & Yoon, S.-J. (2009) MNRAS, 395, 637 "The Fundamental Planes of E+A galaxies and GALEX UV-excess early-type galaxies: revealing their intimate connection"

Mieske, S.; Hilker, M.; Bomans, D. J.; Rey, S.-C.; Kim, S.; Yoon, S.-J.; Chung, C. (2008) A&A, 489, 1023 "Compact stellar systems in the Fornax cluster: a UV perspective"

Yoon, Suk-Jin; Joo, Seok-Joo; Ree, Chang H.; Han, Sang-Il; Kim, Do-Gyun; Lee, Young-Wook (2008) ApJ, 677, 1080 "On the Origin of Bimodal Horizontal Branches in Massive Globular Clusters: The Case of NGC 6388 and NGC 6441"

Rey, Soo-Chang; Yoon, Suk-Jin et al. (2007) ApJS, 173, 643 "GALEX Ultraviolet Photometry of Globular Clusters in M31: Three-Year Results and a Catalog"

Kaviraj, S.; Yoon, S.-J. et al. (2007) ApJS, 173, 619 "UV-Optical Colors As Probes of Early-Type Galaxy Evolution"

Ree, Chang H.; Yoon, Suk-Jin et al. (2007) ApJS, 173, 607 "The Look-back Time Evolution of Far-Ultraviolet Flux from the Brightest Cluster Elliptical Galaxies at z < 0.2"

Schawinski, K.; Yoon, S.-J. et al. (2007) ApJS, 173, 512 "The Effect of Environment on the Ultraviolet Color-Magnitude Relation of Early-Type Galaxies"

Kaviraj, S.; Rey, S.-C.; Rich, R. M.; Yoon, S.-J.; Yi, S. K. (2007) MNRAS, 381, 74 "Better age estimation using ultraviolet-optical colours: breaking the age-metallicity degeneracy"

Kaviraj, S.; Sohn, S. T.; O'Connell, R. W.; Yoon, S.-J.; Lee, Y. W.; Yi, S. K. (2007) MNRAS, 377, 987 "UV bright globular clusters in M87: more evidence for super-He-rich stellar populations?"

Yoon, Suk-Jin; Yi, Sukyoung Ken; Lee, Young-Wook (2006) Science, 311, 1129 "Explaining the Color Distributions of Globular Cluster Systems in Elliptical Galaxies"

Joo, S.-J.; Lee, Y.-W.; Yoon, S.-J.; Han, S.-I.; Chung, C.; Ree, C. H.; Kim, Y.-C.; Sohn, Y.-J.; Yi, S. K. (2006) Baltic, 15, 33 "Super-Helium Stars in Globular Clusters: the Origin of Extreme Horizontal Branch"

Brown, D.; Yi, S.; Han, Z.; Yoon, S.-J. (2006) Baltic, 15, 13 "Binary Population Synthesis, Sdb Stars and the UV Upturn"

Ree, C. H.; Lee, Y.-W.; Sohn, Y.-J.; Yi, S. K.; Yoon, S.-J.; the GALEX Science Team (2006) Baltic, 15, 5 "The Look-Back Time Evolution of the UV Upturn Phenomenon"

Kaviraj, S.; Ferreras, I.; Yoon, S.-J.; Yi, S. K. (2005) A&A, 439, 913 "On the globular cluster formation history of NGC 5128"

Lee, Young-Wook; Yoon, Suk-Jin et al. (2005) ApJ, 621, L57 "Super-Helium-rich Populations and the Origin of Extreme Horizontal-Branch Stars in Globular Clusters"

Rey, Soo-Chang; Yoon, Suk-Jin et al. (2005) ApJ, 619, L119 "Galaxy Evolution Explorer Ultraviolet Photometry of Globular Clusters in M31"

Yi, S. K.; Yoon, S.-J. et al. (2005) ApJ, 619, L111 "Galaxy Evolution Explorer Ultraviolet Color-Magnitude Relations and Evidence of Recent Star Formation in Early-Type Galaxies"

Lee, Young-Wook; Ree, Yoon, Suk-Jin et al. (2005) ApJ, 619, L103 "The Look-back Time Evolution of Far-Ultraviolet Flux from Elliptical Galaxies: The Fornax Cluster and A2670"

Yoon, Suk-Jin; Lee, Young-Wook; Rey, Soo-Chang; Ree, Chang H.; Yi, Sukyoung Ken (2004) Ap&SS, 291, 223 "Horizontal-Branch Stars as Sources of the UV Upturn in Early-Type Galaxies"

Yi, Sukyoung K.; Yoon, Suk-Jin (2004) Ap&SS, 291, 205 "UV Upturn in Elliptical Galaxies: Theory"

Yi, S. K.; Peng, E.; Ford, H.; Kaviraj, S.; Yoon, S.-J. (2004) MNRAS, 349, 1493 "Globular clusters as probes of galaxy evolution: NGC 5128"

Yoon, Suk-Jin; Lee, Young-Wook (2002) Science, 397, 578 "An Aligned Stream of Low-Metallicity Clusters in the Halo of the Milky Way"

Chang, H.-Y.; Yoon, S.-J.; Choi, C.-S. (2002) A&A, 383, L1 "A possible use of Fourier Transform analysis method as a distance estimator"

Rey, Soo-Chang; Yoon, Suk-Jin; Lee, Young-Wook; Chaboyer, Brian; Sarajedini, Ata (2001), AJ, 122, 3219 "CCD Photometry of the Classic Second-Parameter Globular Clusters M3 and M13"

Lee, Hyun-chul; Yoon, Suk-Jin; Lee, Young-Wook (2000) AJ, 120, 998 "The Hβ Index as an Age Indicator of Old Stellar Systems: The Effects of Horizontal-Branch Stars"

Sohn, Young-Jong; Rhee, Myung-Hyun; Yoon, Suk-Jin (1999) JASS, 16, 105 "Absorption Line Gradients of an Elliptical Galaxy NGC 5322"

Sohn, Young-Jong; Yoon, Suk-Jin; Oh, Jungmin (1999) JASS, 16, 1 "Absorption Line Gradients in the Spectrum of an Elliptical Galaxy NGC 5846A"

Yoon, S.-J.; Lee, H.-C.; Lee, Y.-W. (1998) JASS, 15, 53 "The Hβ Index and the Ages of Old Stellar Systems"

Non-refereed Papers that Have Used the YEPS Models

Kim, Hak-Sub; Yoon, Suk-Jin (2015) PKAS, 30, 261 "The Non-Linearity Effect on the Color-to-Metallicity Conversion of Globular Clusters in NGC 5128"

Chung, Chul; Yoon, Suk-Jin; Lee, Sang-Yoon; Lee, Young-Wook (2015) PKAS, 30, 489 "Is Calcium II Triplet a Good Metallicity Indicator of Globular Clusters in Early-type Galaxies?"

Yoon, Suk-Jin (2013) Memorie della Societa Astronomica Italiana, 84, 87 "A new scenario for globular cluster color bimodality and its implication for host galaxy formation"

Ree, C. H., Lee, Y.-W., Yi, S., Yoon, S.-J., & The GALEX Science Team (2009) in New Quests in Stellar Astrophysics. II. Ultraviolet Properties of Evolved Stellar Populations, p. 75 "GALEX UV Observations of Elliptical Galaxies in Abell Clusters at z < 0.2"

Kim, Sohn, Chung, & Yoon (2009) BAAS, 213, 442.02 "Multi-band Photometry of NGC 1399 Globular Cluster System:A Crucial Test for the Origin of Color Bimodality"

Choi, Y, Goto, T., & Yoon, S.-J. (2009) BAAS, 213, 424.34 "The Possible Evolutionary Connection between E+A Galaxies and GALEX UV-excess Early-type Galaxies"

Bae, H.-J., Yun, K., Choi, Y., & Yoon, S.-J. (2009) BAAS, 213, 420.05 "An Evolutionary Connection Between AGNs and GALEX UV-excess Early-type Galaxies"

Yoon, Suk-Jin; Chung, Chul (2009) in Globular Clusters - Guides to Galaxies, p. 381 "On the Globular Cluster Color Distributions "

Yoon, Suk-Jin; Yi, Sukyoung Ken; Lee, Young-Wook (2009) in Globular Clusters - Guides to Galaxies, p. 367 "A New Explanation of Globular Cluster Color Distributions"

Rey, Soo-Chang; Sohn, Sangmo T.; Rich, R. Michael; Yoon, Suk-Jin; Chung, Chul; Yi, Sukyoung K.; Lee, Young-Wook (2009) in Globular Clusters - Guides to Galaxies, p. 221 "GALEX UV Observations of M31 Globular Clusters"

Chung, Chul; Lee, Young-Wook; Yoon, Suk-Jin; Joo, Seok-Joo; Han, Sang-Il (2009) in Globular Clusters - Guides to Galaxies "Super-He-Rich Populations in Globular Clusters"

Kim, S.; Tamura, N.; Yoon, S. J. et al. in Panoramic Views of Galaxy Formation and Evolution (ASP Conference), Vol. 399, p. 471 "M87 Globular Cluster System"

Ree, C. H.; Lee, Y. W.; Yi, S. K.; Yoon, S. J. (2007) in From Stars to Galaxies: Building the Pieces to Build Up the Universe (ASP Conference), Vol. 374, p. 503 "GALEX Observations of the Look-back Time Evolution of the UV Upturn Phenomenon"

Rey, Soo-Chang; Sohn, Sangmo T.; Rich, R. Michael; Yoon, Suk-Jin; Chung, Chul; Yi, Sukyoung K.; Lee, Young-Wook in Galaxy Evolution Across the Hubble Time (IAU Symposium), Vol. 235, p. 332 "GALEX Ultraviolet Observations of Globular Clusters in Nearby Galaxies"

Kim, Sooyoung; Yoon, S.; Kim, H. (2006) BAAS, 209, 100.06 "Multi-band Photometry of Globular Cluster Systems"

Cho, Hye-Jeon; Lee, Y.; Yoon, S. (2006) BAAS, 209, 27.06 "Surface Brightness Fluctuations of Old Stellar Systems in UV and Optical Passbands as Population Indicators"

Rey, S.-C.; Yoon, S.-J. et al. (2004) BAAS, 205, 175.02 "GALEX UV Observations of Globular Clusters in M31 and Milky Way"

Yoon, S.-J.; Yi, S.; Kaviraj, S.; Khochfar, S.; GALEX Science Team (2004) BAAS, 205, 25.08 "GALEX Early-Type Galaxies in the Local Universe: Properties of Recent Star Formation and its Influence on the Scaling Relations"

Lee, Y.-W.; Yoon, S.-J. et al. (2003) BAAS, 203, 470 "GALEX UV observations of elliptical galaxies in Abell clusters with 0.07 < z < 0.20"

Yoon, S.-J.; Lee, Y.-W. (2003) in New Horizons in Globular Cluster Astronomy (ASP Conference), Vol. 296, p. 513 "An Aligned Stream of the Most Metal-Poor Globular Clusters in the Halo of the Milky Way"

Lee, Y.-W.; Rey, S.-C.; Yoon, S.-J.; Ree, C. H.; Sohn, Y.-J.; Joo, J.-M. (2003) in New Horizons in Globular Cluster Astronomy (ASP Conference), Vol. 296, p. 495 "On the Origin of ω Centauri and Other Massive Globular Clusters"

Rey, S.-C.; Lee, Y.-W.; Yoon, S.-J.; Sohn, Y.-J.; Chaboyer, B.; Sarajedini, A. (2003) in New Horizons in Globular Cluster Astronomy (ASP Conference), Vol. 296, p. 400 "Horizontal-Branch Morphology as an Age Indicator"

Lee, Hyun-Chul; Yoon, Suk-Jin; Lee, Young-Wook (2002) in Extragalactic Star Clusters (IAU Symposium), Vol. 207, p. 721 "The Hβ Index As a Chronometer of Extragalactic Globular Cluster Systems"

Lee, Young-Wook; Lee, Hyun-Chul; Yoon, Suk-Jin; Rey, Soo-Chang; Chaboyer, Brian (2002) in Extragalactic Star Clusters (IAU Symposium), Vol. 207, p. 110 "Relative Ages from Horizontal-Branch Morphology : Revisited"

Yoon, S.-J.; Lee, Y.-W. (2002) in Omega Centauri, A Unique Window into Astrophysics (ASP Conference), Vol. 265, p. 381 "A Stream of Metal-Poor Globular Clusters in the Galactic Halo: New Evidence for Accretion"

Lee, Y.-W.; Rey, S.-C.; Ree, C. H.; Joo, J.-M.; Sohn, Y.-J.; Yoon, S.-J. (2002) in Omega Centauri, A Unique Window into Astrophysics (ASP Conference), Vol. 265, p. 305 "ω Centauri as a Disrupted Dwarf Galaxy: Evidence from Multiple Stellar Populations"

Ree, C. H.; Yoon, S.-J.; Rey, S.-C.; Lee, Y.-W. (2002) in Omega Centauri, A Unique Window into Astrophysics (ASP Conference), Vol. 265, p. 305 "Synthetic Color-Magnitude Diagrams for ω Centauri and Other Massive Globular Clusters with Multiple Populations"

Yoon, S.-J.; Lee, Y.-W.; Yi, S.; Sohn, Y.-J.; Rey, S.-C.; Byun, Y.-I. (2001) BAAS, 198, 55.05 "The UV color gradients within nearby ellipticals and spiral bulges as probes of their formation history"

Lee, Y.-W.; Yi, S.; Yoon, S.-J.; Sohn, Y.-J.; Rey, S.-C.; Byun, Y.-I. (2001) BAAS, 198, 55.04 "The evolution of UV flux from elliptical galaxies as probes of star formation history in the early-type systems"

Lee, Hyun-Chul; Yoon, Suk-Jin; Lee, Young-Wook (2001) in Astrophysical Ages and Times Scales (ASP Conference), Vol. 245, p. 445 "Age Estimation of Extragalactic Globular Cluster Systems Using Hβ Index"

Lee, Young-Wook; Yoon, Suk-Jin; Rey, Soo-Chang; Chaboyer, Brian (2001) in Astrophysical Ages and Times Scales (ASP Conference), Vol. 245, p. 445 "Horizontal Branch Morphology as an Age Indicator"

Yoon, S.-J.; Lee, C.-H.; Lee, Y.-W. (2000) BAAS, 196, 41.02 "Multiple Stellar Populations of Some Massive Galactic Globular Clusters as Tracers of Merger Events"

Lee, Y.-W.; Lee, H.-c.; Yoon, S.-J. (1999) BAAS, 193, 124.08 "The Effects of Horizontal-Branch Stars on the Strength of the Hβ Line and the Ages of Old Stellar Systems"

Lee, Y.-W.; Yoon, S.-J.; Lee, H.-C.; Woo, J.-H. (1999) in Spectrophotometric Dating of Stars and Galaxies (ASP Conference), Vol. 192, p. 185 "Horizontal-Branch Stars as an Age Indicator"