2018/08/10 by Jinhyuk Ryu, Myung Gyoon Lee
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Galactic plane #Galaxy #Globular cluster #Infrared #Milky Way #Physics #Red-giant branch #Sky #Stars #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.3847/2041-8213/aad8b7
8 pages, 3 figures, accepted to ApJL
arxiv created 2018/08/10 · openalex publication_date 2018/08/20 · arxiv updated 2018/08/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract The spatial distribution of known globular clusters (GCs) in the Milky Way shows that the current census of GCs is incomplete in the direction of the Galactic plane. We present the discovery of two new GCs located close to the Galactic plane in the sky. These two GCs, RLGC 1 and RLGC 2, were discovered serendipitously during our new cluster survey based on near-infrared and mid-infrared survey data. The two GCs show a grouping of resolved stars in their K -band images and the presence of faint diffuse light in their outer regions in the Wide-field Infrared Survey Explorer W1-band images. They also show prominent red giant branches (RGBs) in their K versus ( J − K ) color–magnitude diagrams (CMDs). We determine structural parameters of the two GCs using King profile-fitting on their K -band radial number density profiles. The determined values are consistent with those of known GCs. Finally, we determine the distances, metallicities, and reddenings of the two GCs using the isochrone fitting on their CMDs. For the fitting, we assume that the ages of the two GCs are 12.6 Gyr and the brightest RGB stars of each cluster correspond to the tip of the RGB. Distances and metallicities of the two GCs are estimated to be d = 28.8 ± 4.3 kpc and [Fe/H] = −2.2 ± 0.2 for RLGC 1 and d = 15.8 ± 2.4 kpc and [Fe/H] = −2.1 ± 0.3 for RLGC 2. These results show that the two GCs are located at the far-half region of the Milky Way and they may belong to the halo of the Milky Way.