Search Publications
AGB and Post-AGB Stars versus Planetary Nebulae and Young Stellar Objects: Properties in Visual and IR Bands
Suh, Kyung-Won
We investigate the properties of AGB and post-AGB (PAGB) stars, planetary nebulae, and young stellar objects (YSOs) in our Galaxy through an analysis of observational data covering visual and infrared (IR) wavelengths. Utilizing datasets from IRAS, 2MASS, AllWISE, Gaia DR3, and the SIMBAD object database, we perform an in-depth comparison between …
New Eruptive YSOs from SPICY and WISE
Jose, Jessy; Johnstone, Doug; Lee, Jeong-Eun +6 more
This work presents four high-amplitude variable YSOs (≃3~mag at near- or mid-IR wavelengths) arising from the SPICY catalog. Three outbursts show a duration that is longer than 1 year, and are still ongoing. And additional YSO brightened over the last two epochs of NEOWISE observations and the duration of the outburst is thus unclear. Analysis of …
A Deep Optical Survey of Young Stars in the Carina Nebula. I. UBVRI Photometric Data and Fundamental Parameters
Lim, Beomdu; Chun, Moo-Young; Hur, Hyeonoh
We present the deep homogeneous UBVRI photometric data of 135,071 stars down to V ~ 23 mag and I ~ 22 mag toward the Carina Nebula. These stars are cross-matched with those from the previous surveys in the X-ray, near-infrared, and mid-infrared wavelengths as well as the Gaia Early Data Release 3 (EDR3). This master catalog allows us to select rel…
Diverse Chemo-Dynamical Properties of Nitrogen-Rich Stars Identified from Low-Resolution Spectra
Beers, Timothy C.; Lee, Young Sun; Kim, Young Kwang +1 more
The second generation of stars in the globular clusters (GCs) of the Milky Way (MW) exhibit unusually high N, Na, or Al, compared to typical Galactic halo stars at similar metallicities. The halo field stars enhanced with such elements are believed to have originated in disrupted GCs or escaped from existing GCs. We identify such stars in the meta…
A Search for Exoplanets around Northern Circumpolar Stars. IX. A Multi-Period Analysis of the M Giant HD 135438
Lee, Byeong-Cheol; Park, Myeong-Gu; Lim, Beomdu +4 more
It is difficult to distinguish the pure signal produced by an orbiting planetary companion around giant stars from other possible sources, such as stellar spots, pulsations, or certain activities. Since 2003, we have obtained radial (RV) data from evolved stars using the high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) …
A Search for Exoplanets around Northern Circumpolar Stars VII. Detection of Planetary Companion Orbiting the Largest Host Star HD 18438
Lee, Byeong-Cheol; Park, Myeong-Gu; Choi, Yeon-Ho +3 more
We have been conducting a exoplanet search survey using Bohyunsen Observatory Echelle Spectrograph (BOES) for the last 18 years. We present the detection of exoplanet candidate in orbit around HD 18438 from high-precision radial velocity (RV) mesurements. The target was already reported in 2018 (Bang et al. 2018). They conclude that the RV variati…
Dating the Stars in the Calendrical Method Shoushili of the Yuan Dynasty
Ahn, Sang-Hyeon
Shoushili was the official calendrical method promulgated in 1280 CE by the Yuan dynasty. It contains a list of the angular spans in right ascensions for the 28 lunar lodges. They are known to have been measured by Guo Shoujing with his advanced instruments with an unprecedented precision or reading error of 5'. Such precise data are useful to det…
Estimation of Nitrogen-to-Iron Abundance Ratios from Low-Resolution Spectra
Beers, Timothy C.; Lee, Young Sun; Masseron, Thomas +1 more
We present a method to determine nitrogen abundance ratios with respect to iron ([N/Fe]) from molecular CN-band features observed in low-resolution (R ∼ 2000) stellar spectra obtained by the Sloan Digital Sky Survey (SDSS) and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). Various tests are carried out to check the systema…
Infrared Properties of OGLE4 Mira Variables in Our Galaxy
Suh, Kyung-Won
We investigate infrared properties of OGLE4 Mira variables in our Galaxy. For each object, we cross-identify the AllWISE, 2MASS, Gaia, and IRAS counterparts. We present various IR two-color diagrams (2CDs) and period-magnitude and period-color relations for the Mira variables. Generally, the Mira variables with longer periods are brighter in the I…
V608 Cassiopeiae: A W UMa-Type Eclipsing Binary with Two Possible Circumbinary Companions
Lee, Jae Woo; Park, Jang-Ho
We present the photometric properties of V608 Cas from detailed studies of light curves and eclipse timings. The light curve synthesis indicates that the eclipsing pair is an overcontact binary with parameters of ΔT = 155 K, q = 0.328, and f = 26%. We detected the third light ℓ_{3}, which corresponds to about 8% and 5% of the total systemic light …