A5050316864- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Pulsars and Gravitational Waves Research
- Geomagnetism and Paleomagnetism Studies
- Advanced Semiconductor Detectors and Materials
- Nuclear Physics and Applications
- Adaptive optics and wavefront sensing
- Geophysics and Gravity Measurements
- High-pressure geophysics and materials
- Software Engineering Techniques and Practices
- Pediatric Urology and Nephrology Studies
- International Business and FDI
- Pharmaceutical and Antibiotic Environmental Impacts
- Viral-associated cancers and disorders
- Laser-induced spectroscopy and plasma
- Atmospheric and Environmental Gas Dynamics
- Gas Sensing Nanomaterials and Sensors
- Innovation and Knowledge Management
- Cholangiocarcinoma and Gallbladder Cancer Studies
- Entrepreneurship Studies and Influences
Yunnan Observatories
2021-2024
Chinese Academy of Sciences
2021-2024
Zhejiang University of Technology
2024
Zhejiang Shuren University
2024
Georgia State University
2014-2023
University of Hong Kong
2022
Liaoning University of International Business and Economics
2010
The B-emission line stars are rapid rotators that were probably spun up by mass and angular momentum accretion through transfer in an interacting binary. Mass will strip the donor star of its envelope to create a small hot subdwarf remnant. Here we report on Hubble Space Telescope/STIS far-ultraviolet spectroscopy sample Be reveals presence sdO companion calculation cross-correlation functions observed model spectra. We clearly detect spectral signature 10 13 sample, signals indicate hot,...
Abstract Nurturing specialized and sophisticated enterprises is a vital strategic initiative to mitigate the dependency on crucial technologies promote competitiveness of Chinese manufacturing industry. Basing technology, organization, environment (TOE) framework, combined with geographic concentration, qualitative comparative analysis (QCA), data envelopment (DEA) methods, this article analyzes conducive business for growth “little giant” (LGEs) from configurational perspective. It takes...
There is growing evidence that some Be stars were spun up through mass transfer in a close binary system, leaving the former donor star as hot, stripped-down object. are five known cases of with hot subdwarf (sdO) companions discovered International Ultraviolet Explorer (IUE) spectroscopy. Here we expand search for Be+sdO candidates using archival FUV spectra from IUE. We collected IUE 264 and formed cross-correlation functions (CCFs) model spectrum subdwarf. Twelve new candidate systems...
Close binary interactions may play a critical role in the formation of rapidly rotating Be stars. Mass transfer can result mass gainer star spun up by accretion and angular momentum, while donor is stripped its envelope to form hot faint helium star. FUV spectroscopy has led detection about 20 such Be+sdO systems. Here we report on three-year program high quality designed determine orbital periods physical properties five These binaries are long period systems with $P =$ 95 237 days small...
Classical Be stars are possible products of close binary evolution, in which the mass donor becomes a hot, stripped O or B-type subdwarf (sdO/sdB), and gainer spins up grows disk to become star. While several Be+sdO binaries have been identified, dynamical masses other fundamental parameters available only for single system, limiting confrontation with evolution models. In this work, we present direct interferometric detections sdO companions three 28 Cyg, V2119 60 all were previously found...
Abstract The 11th data release of the LAMOST survey provides fundamental stellar param-
eters but lacks detailed abundance measurements for α-elements, crucial understanding
stellar populations and Galactic chemical evolution. In this study, we derive abundances of
oxygen (O), magnesium (Mg), silicon (Si), calcium (Ca), titanium (Ti) over 6.8 mil-
lion stars using DR11 low-resolution spectra. To ensure reliable measurements,
we select 1,086 OCs...
Massive stars play key roles in many astrophysical processes. Deriving atmospheric parameters of massive is important to understand their physical properties and thus are inputs trace evolution. Here we report our work on adopting the data-driven technique Stellar LAbel Machine ({\tt SLAM}) with non-LTE TLUSTY synthetic spectra as training dataset estimate stellar LAMOST optical for early-type stars. We apply two consistency tests verify this machine learning method compare labels given by...
Abstract Because many classical Be stars may owe their nature to mass and angular-momentum transfer in a close binary, the present masses, temperatures, radii of components are high interest for comparison stellar evolution models. Object κ Dra is 61.5 day single-lined binary with B6 IIIe primary. With CHARA Array instruments MIRC/MIRC-X MYSTIC, we detected secondary at (approximately photospheric) flux ratios 1.49% ± 0.10% 1.63% 0.09% H K band, respectively. From large diverse optical...
We present a spectroscopic investigation of the Be+sdO binary system HR 2142 that is based upon large sets ultraviolet observations from International Ultraviolet Explorer and ground-based H-alpha observations. measured radial velocities for Be star component these spectra, computed revised orbit. In order to search spectral signature hot subdwarf, we cross-correlated short wavelength end each IUE spectrum with model spectrum, then used predicted Doppler shifts subdwarf shift-and-add all...
Abstract We used archival International Ultraviolet Explorer ( IUE) high-dispersion, short wavelength spectra data to search for evidence of the hot subdwarf companions six rapidly rotating Be stars in binary systems. searched signature a companion through an analysis cross-correlation functions (CCFs) observed and model that were separated into primary secondary components using Doppler tomography algorithm adopted spectroscopic orbital solutions. A positive detection flux from was made...
Context . In early-type Be stars, groups of nonradial pulsation (NRP) modes with numerically related frequencies may be instrumental for the release excess angular momentum through mass-ejection events. Difference and sum/harmonic often form additional groups. Aims The purpose this study is to find out whether a similar frequency pattern occurs in cooler third-magnitude B7-8 IIIe shell star ν Pup. Methods Time-series analyses were performed space photometry BRITE-Constellation (2015,...
Abstract The origin of the bright and hard X-ray emission flux among γ Cas subgroup B-emission line (Be) stars may be caused by gas accretion onto an orbiting white dwarf (WD) companion. Such Be+WD binaries are predicted outcome a second stage mass transfer from helium star donor to rapidly rotating gainer star. stripped become small hot dwarfs that extremely faint compared their Be companions. Here we discuss model predictions about physical orbital properties binaries, show current...
Abstract Hierarchical massive quadruple systems are ideal laboratories for examining the theories of star formation, dynamical evolution, and stellar evolution. The successive mergers hierarchical might explain mass gap between neutron stars black holes. Looking light curves O-type binaries identified by LAMOST, we find a (2+2) system: TYC 3340-2437-1, located in bow-shock nebula (SBN). It has probability over 99.99% being system derived from surface density vicinity stars. Its inner orbital...
Abstract EL CVn is the prototype of a class eclipsing binaries that consist an A- or F-type main-sequence star and hot, low-mass, pre-He white dwarf (pre-He WD), stripped down remains former mass donor. Here we present first direct detection characterization spectrum WD in was made possible through far-UV spectroscopy with Hubble Space Telescope Cosmic Origins Spectrograph. These spectra straddle wavelength range where flux dominance shifts from to A star. Radial velocities both components...
Binaries consisting of a hot subdwarf star and an accreting white dwarf (WD) are sources gravitational wave radiation at low frequencies possible progenitors type Ia supernovae if the WD mass is large enough. Here, we report discovery third binary known this kind: it consists O (sdO) with orbital period 3.495 hours shrinkage 0.1 s in 6 yr. The sdO overfills its Roche lobe likely transfers to via accretion disk. From spectroscopy, obtain effective temperature...
Massive binaries play significant roles in many fields. Identification of massive stars, particularly binaries, is great importance. In this paper, by adopting the technique measuring equivalent widths several spectral lines, we identified 9,382 early-type stars from LAMOST medium-resolution survey and divided sample into four groups, T1 ($\sim$O-B4), T2 ($\sim$B5), T3 ($\sim$B7), T4 ($\sim$B8-A). The relative radial velocities $RV_{\rm rel}$ were calculated using Maximum Likelihood...
The bright and understudied classical Be star HD 6226 has exhibited multiple outbursts in the last several years during which grew a viscous decretion disk. We analyze 659 optical spectra of system collected from 2017-2020, along with UV spectrum Hubble Space Telescope high cadence photometry both TESS KELT survey. find that spectral type B2.5IIIe, rotation rate 74% critical. is nearly pole-on an inclination $13.4$ degree. confirm spectroscopic pulsational properties previously reported,...
Binary evolution leads to the formation of important objects crucial development astrophysics, but statistical properties binary populations are still poorly understood. The LAMOST-MRS has provided a large sample stars study populations, especially for mass ratio distributions and fractions. We have devised Peak Amplitude Ratio (PAR) approach derive system based on results obtained from its spectrum. By computing cross-correlation function (CCF), we established relationship between derived...
Be stars are B-type main-sequence that display broad Balmer emission lines in their spectra. Identification of population is essential to further examine the formation and evolutionary models. We report detection classical (CBe) from observations with Large sky Area Multi-Object fiber Spectroscopic Telescope Medium Resolution Survey Date Release 7 (LAMOST MRS DR7). used a deep convolutional neural network, ResNet, an 18-layer module morphology H alpha profile. identified 1,162 candidate...
Abstract The late-type Be star β CMi is remarkably stable compared to other stars that have been studied. This has led a realistic model of the outflowing disk by Klement et al. These results showed likely truncated at finite radius from star, which suggest evidence for an unseen binary companion in orbit. Here we report on analysis Ritter Observatory spectroscopic archive search elusive companion. We detect periodic Doppler shifts wings H α line with period 170 days and amplitude 2.25 km s...
Massive binary stars play a crucial role in many astrophysical fields. Investigating the statistical properties of massive is essential to trace formation and constrain evolution stellar populations. However, no consensus has been achieved on stars, mainly due lack large homogeneous sample spectroscopic observations. We study intrinsic fraction $f_{\rm b}^{\rm in}$ distributions mass ratio $f(q)$ orbital period $f(P)$ early-type (comprised O-, B-, A-type stars) investigate their dependences...
Abstract Runaway stars are OB-type ejected from their birthplace with large peculiar velocities. The leading hypothesis addressed in formation includes the supernova ejection mechanism and dynamic scenario. Identification of runaway populations is first step to investigating evolution. Here we present our work searching for Galactic candidate Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) Medium Resolution Survey Data Release 8 (DR8) database. After studying kinematic...
Mass transfer in an interacting binary will often strip the mass donor of its entire envelope and spin up gainer to near critical rotation. The nearby B-type star Regulus represents a post-mass stage: it is rapid rotator with very faint companion 40 d orbit. Here we present results search for spectral features stripped-down extensive set high S/N resolution spectra obtained CFHT/ESPaDOnS TBL/NARVAL spectrographs. We first determine revised orbital elements order accurate estimates Doppler...
The star system HR 6819 was recently proposed by Rivinius et al. as the site of nearest example a stellar mass black hole. Their spectra show evidence two components: B3 III in 40 d orbit and stationary B-emission line star. Based upon orbital function lack spectral component with reflex motion, suggested that is triple consisting an inner plus hole binary orbited distant Be Here we present alternative model based examination H-alpha emission their spectra. We displays small motion expected...