A5001454236- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Astronomical Observations and Instrumentation
- Atomic and Molecular Physics
- Pulsars and Gravitational Waves Research
- Spectroscopy and Laser Applications
- Advanced Chemical Physics Studies
- Impact of Light on Environment and Health
- Atmospheric Ozone and Climate
- Astronomical and nuclear sciences
- Advanced Thermodynamics and Statistical Mechanics
- Adaptive optics and wavefront sensing
- Bioinformatics and Genomic Networks
- Phase Equilibria and Thermodynamics
- Computational Drug Discovery Methods
- Optical Polarization and Ellipsometry
- Cell Image Analysis Techniques
Yunnan Observatories
2015-2024
Central South University
2024
Chinese Academy of Sciences
2015-2024
University of Chinese Academy of Sciences
2007-2024
National Astronomical Observatories
2005-2012
Since September 2018, LAMOST starts a new 5-year medium-resolution spectroscopic survey (MRS) using bright/gray nights. We present the scientific goals of LAMOST-MRS and propose near optimistic strategy survey. A complete footprint is also provided. Not only regular survey, but time-domain being conducted since 2018 will be end in 2023. According to detailed plan, we expect that can observe about 2 million stellar spectra with ~7500 limiting magnitude around G=15 mag. Moreover, it provide...
The stability of mass transfer is important in the formation contact binaries from detached when primaries initially fill their Roche lobes. Using Eggleton's stellar evolution code, we investigate and short-period limit by considering effect instability transfer. It found that with decreasing initial primary 0.89M$_{\rm \odot}$ to 0.63M$_{\rm \odot}$, range ratio decreases for experience stable evolve into contact. If less than would dynamically unstable These systems a common envelope...
Abstract Common envelope evolution (CEE) physics plays a fundamental role in the formation of binary systems, such as merging stellar gravitational wave sources, pulsar binaries, and Type Ia supernovae. A precisely constrained CEE has become more important age large surveys detectors. We use an adiabatic mass-loss model to explore how total energy donor changes function remnant mass. This provides self-consistent way calculate binding donor. For comparison, we also through integrating from...
Abstract The radial velocity (RV) is a basic physical quantity that can be determined through the Doppler shift of spectrum star. precision RV measurement depends on resolution we used and accuracy wavelength calibration. In this work, velocities Large Sky Area Multi-Object Fibre Spectroscopic Telescope-II (LAMOST-II) medium-resolution ( R ∼ 7500) spectra are measured for 1,594,956 (each has two wavebands) matching with templates. A set standard stars to recalibrate zero point measurement,...
The origin and evolution of W UMa systems are discussed based on All Sky Automated Survey (ASAS) data the mean kinematic ages four subgroups 97 field contact binaries (FCBs). period distribution eclipsing discovered by ASAS suggests that a limit to tidal locking for close is about 2.24 days, so most might be formed from detached with periods P ≲ maximum advanced time system 3.23 Gyr. Moreover, secular angular momentum (AM), mass, orbital FCBs were investigated according ages, which set AM...
Well-determined physical parameters of 130 W UMa systems have been collected from the literature. Based on these data, evolutionary status and dynamical evolution are investigated. It is found that there no difference between W- A-type in $M-J$ diagram which consistent with results derived analysis observed spectral type, $M-R$ $M-L$ diagrams systems. indicate a large amount energy should be transferred more massive to less component so they not thermal equilibrium undergo relaxation...
Using Eggleton's stellar evolution code, we study the minimum mass ratio ($q_{\rm min}$) of W Ursae Majoris (W UMa) binaries that have different primary masses. It is found UMa decreases with increasing if primary's less than about 1.3$M_{\rm \odot}$, and above this roughly constant. By comparing theoretical observational data, it existence low-$q$ systems can be explained by structure primaries This suggests dimensionless gyration radius ($k_1^2$) thus very important in determining ratio....
Identifying bifurcated blue straggler (BS) sequences in color-magnitude diagrams (CMDs) of star clusters has long been regarded as a powerful diagnostic for distinguishing different BS formation mechanisms. While such bifurcations are typically associated with core-collapsed clusters, their detection dynamically young raises new questions about origins. In this study, using high-precision proper motion data derived from Hubble Space Telescope multi-epoch observations, we confirm the...
Abstract Identifying bifurcated blue straggler (BS) sequences in color–magnitude diagrams (CMDs) of star clusters has long been regarded as a powerful diagnostic for distinguishing different BS formation mechanisms. While such bifurcations are typically associated with core-collapsed clusters, their detection dynamically young raises new questions about origins. In this study, using high-precision proper motion data derived from Hubble Space Telescope multiepoch observations, we confirm the...
We develop optical and near-infrared colour-selection criteria based on the model colours of binaries consisting a white dwarf main-sequence star. Using our algorithm, we present catalogue 523 dwarf–main sequence (WDMS) from spectroscopic Sloan Digital Sky Survey Data Release 7 (SDSS DR7), most them previously identified. Among them, identify 86 objects as new WDMS binaries. 95 candidates are also found photometric SDSS DR7, cross-matched with United Kingdom Infrared Telescope (UKIRT) 5...
The detached-binary channel is an important for the formation of contact binaries, according to which a detached binary might evolve into by evolutionary expansion components, or angular momentum loss through effect magnetic braking (MB). We have carried out detailed population synthesis (BPS) study this channel, and obtained parameter regions binaries contact. Combining observations from $\emph{Kepler}$ satellite with our results, we found that ratio birth rate progenitors greater than...
Based on the physical parameters of 133 W Ursae Majoris (W UMa) type contact binaries, energy transfer and its effects secondaries in UMa binaries are investigated. Relations given between mass ratio (q) for relative rates, i.e. U1, transferred luminosity to surface primary, U2, nuclear secondary. The theoretical curves(U1 versus q U2 q) derived based various assumptions: that two components each system nearly identical effective temperature just fill their inner Roche lobes, primaries...
Abstract Two blue-straggler sequences discovered in globular cluster M30 provide a strong constraint on the formation mechanisms of blue stragglers. We study binaries through binary evolution, and find that evolution can contribute to stragglers both sequences. Whether is located sequence or red depends contribution mass donor total luminosity binary, which generally observed as single star clusters. The have cool white dwarf companion, while majority (∼60%) objects are still experiencing...
Abstract The bifurcated patterns in the color–magnitude diagrams of blue straggler stars (BSSs) have attracted significant attention. This type special (but rare) pattern two distinct sequences is commonly interpreted as evidence that cluster core-collapse-driven stellar collisions are an efficient formation mechanism. Here, we report detection a distribution young Large Magellanic Cloud cluster, NGC 2173. Because cluster’s low central number density and its age, dynamical analysis shows...
Observations have revealed the presence of multiple stellar populations in globular clusters (GCs) that exhibit wide abundance variations and sequences Hertzsprung–Russell (HR) diagram. We present a scenario for formation GCs. In this scenario, initial GCs are single-generation clusters, our model predicts stars with anomalous abundances observed merged accretor produced by binary interactions—rapidly rotating at moment their formation—and these more massive than normal single same...
ABSTRACT Close detached binaries were theoretically predicted to evolve into contact by three subtypes of case A binary evolution, cases AD, AR, and AS, which correspond the formation during dynamic-, thermal-, nuclear-time-scale mass transfer phases, respectively. It is unclear, however, what difference between in these subtypes, whether all can account for observed W Ursae Majoris (W UMa) binaries. Using Eggleton’s stellar evolution code with non-conservative assumption, I obtained...
Employing tidally enhanced stellar wind, we studied in binaries the effects of metallicity, mass ratio primary to secondary, tidal enhancement efficiency and helium abundance on formation blue hook (BHk) stars globular clusters (GCs). A total 28 sets binary models combined with different input parameters are studied. For each set model, presented a range initial orbital periods that is needed produce BHk binaries. All could within periods. We also compared our results observation Teff–logg...
Abstract Multiple stellar populations (MPs) in most star clusters older than 2 Gyr, as seen by lots of spectroscopic and photometric studies, have led to a significant challenge the traditional view formation. In this field, space-based instruments, particular Hubble Space Telescope (HST), made breakthrough they significantly improved efficiency detecting MPs crowded fields images. The China Station (CSST) HST are sensitive similar wavelength interval, but CSST covers field which is about...
Abstract The first complete charge-coupled device (CCD) light curves in $B$ and $V$ passbands of a neglected contact binary system, CW Cassiopeiae (CW Cas), are presented. They were analyzed simultaneously by using the Wilson Devinney (WD) code (1971, ApJ, 166, 605). photometric solution indicates that Cas is W-type W UMa system with mass ratio $m_{2}/m_{1} =$ 2.234, it marginal state degree $\sim$ 6.5% relatively large temperature difference 327 K between its two components. Based on...
VFTS 102 has a projected rotational velocity (>500 km s−1) and would appear to be the fastest rotating O-type star. We show that its high could understood within framework of binary merger. In merger channel, progenitor evolve into contact while two components are still on main sequence, then merge rapidly single Employing Eggleton's stellar evolution code, we performed calculations mapped out initial parameters in orbital period–mass ratio (P-q) plane. found with mass q0 ≲ 0.7 should have...
The hot subdwarf O/B stars (sdO/Bs) are known as extreme horizontal branch stars, which is of great importance in stellar evolution theory. sdO/Bs generally thought to have a helium-burning core and thin hydrogen envelope $(M_{\rm env }<0.02M_\odot)$. In the canonical binary scenario, considered be stripped cores red giants. However, such scenario cannot explain recently discovered sdO/B binary, SMSS J1920, where strong Ca H$\&$K lines spectrum found. It suggests that this likely originated...
Using a sample of nearly 140,000 primary red clump stars selected from the LAMOST and $Gaia$ surveys, we have identified large "young" [$\alpha$/Fe]-enhanced with stellar ages younger than 6.0 Gyr [$\alpha$/Fe] ratios greater 0.15 dex. The are measured spectra, using machine learning method trained common in LAMOST-APOGEE fields (for [$\alpha$/Fe]) LAMOST-$Kepler$ age). existence these is not expected classical Galactic chemical evolution models. To explore their possible origins, analyzed...
Abstract The multi-color photometric light curves for contact binary AV Puppis (AV Pup) in VR c I bandpasses are presented and analyzed by using the 2013 version of Wilson-Devinney (W-D) code. solutions suggest that Pup is a peculiar A-subtype W UMa with high mass ratio ( q = m 2 / 1 0.896) low fill-out factor f 10%). Combining our newly determined times minimum those collected from literatures, orbital period changes this system investigated. O – C analysis indicates increasing at rate d P...
Several dozen hypervelocity star (HVS) candidates have been reported based on the second data release of Gaia (Gaia DR2). However, it has proven that radial velocities some HVS are not reliable. In this paper, we employ refined astrometric criteria to re-examine DR2, arriving at a more reliable sample and high velocity than those found by previous authors.We develop method called Binary Escape Probability Analysis identify candidates. This allows us work with stars having only two epochs...