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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…
Correlation Study of Temporal and Emission Properties of Quiescent Magnetars
An, Hongjun; Seo, Jiwoo; Lee, Jaewon
We measured temporal and emission properties of quiescent magnetars using archival Chandra and XMM-Newton data, produced a list of the properties for 17 magnetars, and revisited previously suggested correlations between the properties. Our studies carried out with a larger sample, better spectral characterizations, and more thorough analyses not o…
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…
A Search for Exoplanets around Northern Circumpolar Stars. VIII. Filtering Out a Planet Cycle from the Multi-Period Radial Velocity Variations in M Giant HD 36384
Lee, Byeong-Cheol; Park, Myeong-Gu; Lim, Beomdu +6 more
This paper is written as a follow-up observations to reinterpret the radial velocity (RV) of HD 36384, where the existence of planetary systems is known to be ambiguous. In giants, it is, in general, difficult to distinguish the signals of planetary companions from those of stellar activities. Thus, known exoplanetary giant hosts are relatively ra…