120 citations · 946 across the 56 of their papers we have counts for
26 papers · 1 filter
Long-term high-resolution spectroscopic monitoring of the evolved metal-poor binary PS Gem
V. G. Klochkova, V. E. Panchuk, J. K. Zhao +3
We present results of long-term high-resolution spectroscopic monitoring of the extremely low-metallicity star PS Gem (=HD 52961), associated with IRAS 07008+1050. The spectra were…
Probabilistic Stellar Age Estimation for Gaia XP Stars with NGBoost
Xiaokun Hou, Wenbo Wu, Gang Zhao +2
Stellar age is a fundamental quantity for Galactic archaeology, but reliable age estimation for large stellar samples remains challenging. In this work, we develop an uncertainty a…
A Systematic NLTE Study of Very Metal-Poor Stars with Metallicity Down to dex. II. Lithium Abundance and New Insight to the Lithium Plateau
Hong-Liang Yan, Jinxiao Qin, Shuai Liu +12
Metal-poor stars are crucially important for understanding the early Galaxy, first stars, and the Universe. In this series of papers, we present a homogeneous non-local thermodynam…
The Stellar Abundances and Galactic Evolution Survey (SAGES). V. The First Data Release of the DDO51 Band
Qiqian Zhang, Zhou Fan, Gang Zhao +20
We present the first public data release of DDO51 band from the Stellar Abundances and Galactic Evolution Survey (SAGES), based on Nanshan One-meter Wide-field Telescope (NOWT) obs…
Revisiting Ca II Activity Indices in FGK Stars: Systematic Biases in Infrared Triplet Measurements
Xiaozhen Yang, Xiaoting Fu, Mingjie Jian +10
Synthetic-template subtraction is widely used to measure chromospheric activity in large spectroscopic surveys. However, many solar-like FGK stars show systematically negative Ca I…
A Highly Magnetic Ultra Massive White Dwarf with a 23-minute Rotation Period
Jincheng Guo, Xiaofeng Wang, Qichun Liu +17
We present a physical characterization of TMTS J00063798+3104160 (J0006), a rapidly rotating,ultra-massive white dwarf (WD) identified in high-cadence light curves from the Tsinghu…
Looking for Signs of Unresolved Binarity in the Continuum of LAMOST Stellar Spectra
Mikhail Prokhorov, Kefeng Tan, Nikolay Samus +10
We describe an attempt to derive the binarity rate of samples of 166 A-, F-, G-, and K-type stars from LAMOST DR5 and 1000 randomly selected presumably single stars from Gaia DR3 c…
Variable white dwarfs in TMTS: Asteroseismological analysis of a ZZ Ceti star, TMTS J17184064+2524314
Jincheng Guo, Yanhui Chen, Yonghui Yang +24
The Tsinghua University-Ma Huateng Telescope for Survey (TMTS) has been constantly monitoring the northern sky since 2020 in search of rapidly variable stars. To find variable whit…
Mass distribution for single-lined hot subdwarf stars in LAMOST
Zhenxin Lei, Ruijie He, Peter Nemeth +4
Masses for 664 single-lined hot subdwarf stars identified in LAMOST were calculated by comparing synthetic fluxes from spectral energy distribution (SED) with observed fluxes from…
Properties and Asteroseismological analysis of a new ZZ ceti discovered by TMTS
Jincheng Guo, Yanhui Chen, Xiaofeng Wang +24
Tsinghua university-Ma Huateng Telescope for Survey (TMTS) aims to discover rapidly evolving transients by monitoring the northern sky. The TMTS catalog is cross-matched with the w…
Hot subdwarf stars identified in LAMOST DR8 with single-lined and composite spectra
Zhenxin Lei, Ruijie He, Peter Nemeth +6
222 hot subdwarf stars were identified with LAMOST DR8 spectra, among which 131 stars show composite spectra and have been decomposed, while 91 stars present single-lined spectra.…
Four-hundred Very Metal-Poor Stars Studied with LAMOST and Subaru. II. Elemental abundances
Haining Li, Wako Aoki, Tadafumi Matsuno +9
We present homogeneous abundance analysis of over 20 elements for 385 very metal-poor (VMP) stars based on the LAMOST survey and follow-up observations with the Subaru Telescope. I…
Four-hundred Very Metal-poor Stars studied with LAMOST and Subaru. I. Survey Design, Follow-up Program, and Binary Frequency
Wako Aoki, Haining Li, Tadafumi Matsuno +11
The chemical abundances of very metal-poor stars provide important constraints on the nucleosynthesis of the first generation of stars and early chemical evolution of the Galaxy. W…
White dwarfs identified in LAMOST Data Release 5
Jincheng Guo, Jingkun Zhao, Huawei Zhang +5
In this paper, we report white dwarfs identified in the 5th Data Release of the Large Area Multi-Object fibre Spectroscopic Telescope, including spectral types of DA, DB, DC, DZ, a…
Star Formation Timescales of the Halo Populations from Asteroseismology and Chemical Abundances
Tadafumi Matsuno, Wako Aoki, Luca Casagrande +9
We combine asteroseismology, optical high-resolution spectroscopy, and kinematic analysis for 26 halo red giant branch stars in the \textit{Kepler} field in the range of $-2.5<[\ma…
Stellar activity with LAMOST. I. Spot configuration in Pleiades
Xiang-Song Fang, Gang Zhao, Jing-Kun Zhao +2
We use the spectra of Pleiades and field stars from LAMOST DR2 archive to study how spottedness and activity vary as a function of mass at young ages. We obtained standard TiO band…
Three Moving Groups Detected in the LAMOST DR1 Archive
Jingkun Zhao, Gang Zhao, Yuqin Chen +3
We analyze the kinematics of thick disk and halo stars observed by the Large sky Area Multi-Object Fiber Spectroscopic Telescope. We have constructed a sample of 7,993 F, G and K n…
White dwarf-main sequence binaries identified from the LAMOST pilot survey
Juanjuan Ren, Ali Luo, Yinbi Li +5
We present a set of white dwarf-main sequence (WDMS) binaries identified spectroscopically from the Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST, also called t…
M dwarf catalog of LAMOST pilot survey
Z. P. Yi, A. L. Luo, Y. H. Song +17
We present a spectroscopic catalog of 67082 M dwarfs from the LAMOST pilot survey. For each spectrum of the catalog, spectral subtype, radial velocity, equivalent width of H, a…
72 DA White Dwarfs Identified in LAMOST Pilot Survey
J. K. Zhao, A. L. Luo, T. D. Oswalt +1
We present a spectroscopically identified catalogue of 72 DA white dwarfs from the LAMOST pilot survey. 35 are found to be new identifications after cross-correlation with the Eise…
Tracers of chromospheric structure. I. CaII HK emission distribution of 13000 F, G and K stars in SDSS DR7 spectroscopic sample
J. K. Zhao, T. D. Oswalt, G. Zhao +3
We present chromospheric activity index measurements for over 13,000 F, G and K disk stars with high signal-to-noise ratio ( 60) spectra in the Sloan Digital Sky Sur…
The Initial-Final Mass Relation among White Dwarfs in Wide Binaries
Jingkun Zhao, Terry D. Oswalt, Lee Anne Willson +2
We present the initial-final mass relation derived from 10 white dwarfs in wide binaries that consist of a main sequence star and a white dwarf. The temperature and gravity of each…
Fragile Binary Candidates in the SDSS DR8 spectroscopic archive
Jingkun Zhao, Terry D. Oswalt, Gang Zhao
We present a catalog of 80 very wide fragile binary candidates (projected separations > 10000 AU) from the SDSS DR8 spectral archive. The pairs were selected based on proper motion…
Metallicity and Kinematic distributions of Red Horizontal-Branch Stars from the SDSS Survey
Y. Q. Chen, G. Zhao, J. K. Zhao +2
On the basis of a recently derived color-metallicity relation and stellar parameters from the Sloan Digtal Sky Survey Data Release 7 spectroscopic survey, a large sample of red hor…