Ongoing Resarch Projects

RR Lyrae Variables in M33

In contrast to the case of our Milky Way Galaxy or M31, the RR Lyrae in M33, one of spiral galaxies in Local Group, are much less studied. This motivate us to start a series of investigation on M33 RR Lyrae. With a deep photometry of HST fields of M33, we find and analyze hundreds of RR Lyrae. Using the template-light-curve fitting procedure programed by Dr. Andrew Layden, the light curves for RR Lyrae were obtained. The characterization of RR Lyrae provides us information about the reddening to M33, the metalicity distribution, and the distance of M33.

WIYN Open Cluster Study (WOCS)

This is a series of studies focussed on open clusters in Milky Way Galaxy from the collaboration of the WIYN institutions (Wisconsin, Indiana, Yale, and NOAO). WIYN data has great benefits for studying open clusters. Its size of observing field extends up to 1x1 degree, and it provide a 100-fiber multiobject spectrograph and high quality CCD images. WOCS is aiming to investigate over 10 open clusters with wide range of age and metalicity in great detail.

Past Resarch Projects

Washington CCD Photometry of A Bulge Globular Cluster NGC6624

The primary goal of this project was to determine the metalicity of a galactic bulge globular cluster NGC6624 using the two-color digrams of the Washington system (C,M,T1,T2) which is higly sensitive on metalicity. The metalicity distribution of the Milky Way Galaxy along with the galactocentric distance shows a decreasing pattern within 10 kpc and remains a certain level as it goes to outside of the Galatic halo. This metalicity distribution gives us relevent implication on the chemical evolution within Our Galaxy. So the accurate determination of the metalicities for various objects in Our Galaxy is required to understand the formation and evolution of Our Galaxy. From the carefully reduced photometric data, four different color-color diagrams were obtained. Using the relation between the Washington system color indices and the metalicities, we found [Fe/H] = -0.56 +/- 0.27 for NGC6624. The age of the cluster was also determined using Yale isochrone by adopting this metalicity value. The resultant age of the cluster is 13 +/- 2 Gyr. This value is agreed with that of other Glactic bulge populations and less than that of halo globular clusters as young as 2~5 Gyrs. The metalicity and the age of NGC6624 determined in this study are consistent with the characteristic of bulge globular clusters within 3 kpc from the Galactic Center.