Modern Supernova Search

Supernovae play a critical role in observational cosmology as well as in astrophysics of stars and galaxies. Recent era has seen dramatic progress in the research of supernovae. Several programs to search systematically supernovae in nearby to distant galaxies have been very successful. Recent progresses in the modern supernova search are reviewed.Comment: 7 pages (LaTex), aipproc.sty, Presented at the Explosive Pheonomena in Astrophysical Compact Objects meeting, KIAS, May 24-27, 200

Optical and near-IR study of LMC HII region N11AB

N11 (DEM 34), complex HII region located about 4 degrees from the center of the LMC bar, is a very interesting giant interstellar shell. It has a complicated structure and motion. It is located on the edge of an HI concentration. This is the progress report of the study of its two components, A and B at the optical and near-IR wavelengths to investigate stars, dust and ionized gas associated with them. N11A is a compact high-excitation blob and N11B is a bright HII region in this complex, which embeds OB association Lucke-Hodge 10

The Star Cluster System in the Local Group Starburst Galaxy IC 10

We present a survey of star clusters in the halo of IC 10, a starburst galaxy in the Local Group based on Subaru R band images and NOAO Local Group Survey UBVRI images. We find five new star clusters. All these star clusters are located far from the center of IC 10, while previously known star clusters are mostly in the main body. Interestingly the distribution of these star clusters shows an asymmetrical structure elongated along the east and south-west direction. We derive UBVRI photometry of 66 star clusters including these new star clusters as well as previously known star clusters. Ages of the star clusters are estimated from the comparison of their UBVRI spectral energy distribution with the simple stellar population models. We find that the star clusters in the halo are all older than 1 Gyr, while those in the main body have various ages from very young (several Myr) to old (>1 Gyr). The young clusters (<10 Myr) are mostly located in the H{\alpha} emission regions and are concentrated on a small region at 2' in the south-east direction from the galaxy center, while the old clusters are distributed in a wider area than the disk. Intermediate-age clusters (~100 Myr) are found in two groups. One is close to the location of the young clusters and the other is at ~4' from the location of the young clusters. The latter may be related with past merger or tidal interaction.Comment: 11 pages, 12 figures, 1 table; accepted for publication in Ap

A Photometric Study of Five Open Clusters in the SDSS

We present a photometric study of five open clusters (Czernik 5, Alessi 53, Berkeley 49, Berkeley 84, and Pfleiderer 3) in the Sloan Digital Sky Survey. The position and size of these clusters are determined using the radial number density profiles of the stars, and the member stars of the clusters are selected using the proper motion data in the literature. We estimate the reddening, distance, and age of the clusters based on the isochrone fitting in the color-magnitude diagram. The foreground reddenings for these clusters are estimated to be E(B-V) = 0.71 - 1.55 mag. The distances to these clusters are derived to be 2.0 - 4.4 kpc, and their distances from the Galactic center range from 7.57 kpc to 12.35 kpc. Their ages are in the range from 250 Myr to 1 Gyr. Berkeley 49 and Berkeley 84 are located in the Orion spur, Czernik 5 is in the Perseus arm, and Pfleiderer 3 and Alessi 53 are at beyond the Perseus arm.Comment: 18 pages, 21 figures, accepted for publication in JKA

Giant Halos in Dwarf Irregular Galaxies vs. Dwarf Elliptical Galaxies

We present a discovery of a giant stellar halo in NGC 6822, a dwarf irregular galaxy in the Local Group. This halo is mostly made of old red giants, showing striking features: 1) it is several times larger than the main body of the galaxy seen in the optical images, and 2) it is elongated in the direction almost perpendicular to the HI disk of NGC 6822. The structure of this stellar halo looks similar to the shape of dwarf elliptical galaxies, indicating that the halos of dwarf irregular galaxies share the same origin with those of the dwarf elliptical galaxies.Comment: 4 pages, 3 figures, proceedings of IAU Colloquium 198, "Near-Field Cosmology With Dwarf Elliptical Galaxies", editors H. Jerjen and B. Binggeli, Cambridge University Pres