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More than two hundred and fifty thousand spectroscopic binary or variable star candidates discovered by LAMOST
Li, Lin-Jia; Qian, Sheng-Bang; Zhu, Li-Ying +7 more
About 786.4 thousand stars were observed by LAMOST twice or more during the first stage of its spectroscopic survey. The radial velocity differences for about 256 thousand targets are larger than 10 km s-1 and they are possible spectroscopic binary or variable candidates (SBVCs). It is shown that most SBVCs are slightly metal poorer tha…
The W UMa binaries USNO-A2.0 1350-17365531, V471 Cas, V479 Lac and V560 Lac: light curve solutions and global parameters based on Gaia distances
Popov, Velimir A.; Petrov, Nikola I.; Kjurkchieva, Diana P. +1 more
We present photometric observations in Sloan filters g‧, i‧ of the eclipsing W UMa stars USNO-A2.0 1350-17365531, V471 Cas, V479 Lac and V560 Lac. The sinusoidal-like O - C diagram of V471 Cas indicates the presence of a third body with mass 0.12 M ⊙ (a red dwarf) at distance 897 R ⊙. The O - C diagram of V479 Lac reveals a p…
Local standard of rest based on Gaia DR2 catalog
Zhu, Zi; Liu, Jia-Cheng; Ding, Ping-Jie
The local standard of rest (LSR) provides a reference framework for studies of Galactic kinematics. Determination of the LSR corresponds to the measurement of solar peculiar motion, which is under debate due to the fact that different methods and samples have been used. Adopting the astrometric data and line-of-sight velocities of main sequence st…
Photometric investigations on two totally eclipsing contact binaries: V342 UMa and V509 Cam
Zhang, Yu; Li, Kai; Xia, Qi-Qi +6 more
By analyzing two sets of complete BVRcIc light curves for V342 UMa and three sets of complete BVRcIc light curves for V509 Cam, we determined that the two systems are both W-subtype contact binaries and that V342 UMa manifests a shallow contact configuration, while V509 Cam exhibits a medium contact conf…
A compilation of known QSOs for the Gaia mission
Liao, Shi-Long; Qi, Zhao-Xiang; Guo, Su-Fen +1 more
Quasars are essential for astrometry in the sense that they are spatially stationary because of their large distance from the Sun. The European Space Agency (ESA) astrometric satellite Gaia is scanning the whole sky with unprecedented accuracy up to the level of a few µas. However, Gaia’s two-fields-of-view-observation strategy may introduce…
Physical properties of γ Doradus pulsating stars and their relationship with long-period δ Scuti variables
Li, Lin-Jia; Qian, Sheng-Bang; Zhu, Li-Ying +3 more
We present LAMOST data on 168 γ Doradus (γ Dor) pulsating stars including stellar atmospheric parameters of 137 variables and spectral types for all of the samples. The distributions of period (P), temperature (T), gravitational acceleration (log(g)) and metallicity [Fe/H] are shown. It is found that most γ Dor variables are main-sequence stars wi…
Joint hard X-ray observations with ASO-S/HXI and SO/STIX
Krucker, Säm; Su, Yang; Hurford, Gordon J. +1 more
This paper discusses the potential of future joint hard X-ray solar flare observations between the Hard X-ray Imager (HXI) onboard the Advanced Space-based Solar Observatory (ASO-S) mission and the Spectrometer/Telescope for Imaging X-rays (STIX) on Solar Orbiter. The different viewing perspectives of the two telescopes relative to the Sun will al…
Orbital and physical parameters of the close binary system GJ 9830 (HIP 116259)
Al-Wardat, Mashhoor A.; Pathan, J. M.; Masda, Suhail G.
We present the complete set of physical and geometrical parameters of the visual close binary system GJ 9830 for the first time by applying Al-Wardat’s complex method. This method combines magnitude difference from speckle interferometry, synthetic spectral energy distributions of the binary components which are constructed based on grids of Kuruc…
Transition-region explosive events produced by plasmoid instability
Li, Dong
Magnetic reconnection is thought to be a key process in most solar eruptions. Thanks to highresolution observations and simulations, the studied scale of the reconnection process has become smaller and smaller. Spectroscopic observations show that the reconnection site can be very small, which always exhibits a bright core and two extended wings w…
A catalog of DB white dwarfs from the LAMOST DR5 and construction of templates
Luo, A. -Li; Kong, Xiao; Li, Xiang-Ru
In this study, we employ machine learning to build a catalog of DB white dwarfs (DBWDs) from the LAMOST Data Release (DR) 5. Using known DBs from SDSS DR14, we selected samples of high-quality DB spectra from the LAMOST database and applied them to train the machine learning process. Following the recognition procedure, we chose 351 DB spectra of …