A5103144638- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Astrophysical Phenomena and Observations
- Insurance, Mortality, Demography, Risk Management
- Geomagnetism and Paleomagnetism Studies
Australian National University
2021-2024
Chinese Academy of Sciences
2017-2022
Yunnan Observatories
2017-2022
Mount Stromlo Observatory
2021
Kunming Institute of Zoology
2017
University of Chinese Academy of Sciences
2017
Ultra-massive white dwarfs (UMWDs) with masses larger than 1.05Msun are basically believed to harbour oxygen-neon (ONe) cores. Recently, Gaia data reveals an enhancement of UMWDs on Hertzsprung-Russell diagram (HRD), which indicates that extra cooling delay mechanism such as crystallization and elemental sedimentation may exist in the UMWDs. Further studies suggested a portion should have experienced pretty long delays, implying they carbon-oxygen (CO) WDs. However, formation these UMCOWDs...
ABSTRACT Over the past few years, wide-field time-domain surveys such as Zwicky Transient Facility and Optical Gravitational Lensing Experiment have led to discoveries of various types interesting short-period stellar variables, ultracompact eclipsing binary white dwarfs (WDs), rapidly rotating magnetized WDs, transitional cataclysmic variables between hydrogen-rich helium accretion, blue large-amplitude pulsators (BLAPs), which greatly enrich our understandings physics under some extreme...
Blue large-amplitude pulsators (BLAPs) are a newly discovered type of variable star. Their typical pulsation periods on the order few tens minutes, with relatively large amplitudes 0.2-0.4 mag in optical bands, and their rates period changes $10^{-7} yr^{-1}$ (both positive negative). They extremely rare objects attempts to explain origins internal structures have attracted great deal attention. Previous studies proposed that BLAPs may be pre-white dwarfs, masses around $0.3M_\odot$, or...
Abstract Although multidimensional simulations have investigated the processes of double white dwarf (WD) mergers, postmerger evolution only focused on carbon–oxygen (CO) or helium (He) WD merger remnants. In this work, we investigate for first time remnants stemming from oxygen–neon (ONe) WDs with CO WDs. Our simulation results indicate that can evolve to hydrogen- and helium-deficient giants a maximum radius about 300 R ⊙ . models show evidence more massive than 1.95 M ignite Ne before...
From the canonical binary scenario, majority of sdBs are produced from low-mass stars with degenerate cores where helium is ignited in a way flashes. Due to numerical difficulties, models generally constructed more massive non-degenerate cores, leaving several uncertainties on exact characteristics sdB stars. Employing MESA, we systematically studied common envelope (CE) ejection channel, and found that CE channel appear form two distinct groups effective temperature-gravity diagram. One...
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...
Abstract Mixing in the convective core is quite uncertain helium-burning stars. To explore overshooting mixing beyond core, we incorporated k – ω proposed by Li into Modules of Experiments Stellar Astrophysics (MESA), and investigated evolution subdwarf B (sdB) models. We found that development can be divided three stages. When radiative temperature gradient, <?CDATA ${{\rm{\nabla }}}_{\mathrm{rad}}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub>...
ABSTRACT Double white dwarf (WD) merger process and their post-merger evolution are important in many fields of astronomy, such as supernovae, gamma-ray bursts, gravitational waves, so on. The evolutionary outcomes double ultra-massive WD remnants still a subject debate, though the general consensus is that remnant will collapse to form neutron star (NS). In this work, we investigate $2.20\, {\rm M}_{\odot }$ stemmed from coalescence $1.10\, ONe WDs. We find ignites off-centre neon burning...
ABSTRACT Most subdwarf B (sdB) + Helium white dwarf (He WD) binaries are believed to be formed from a particular channel. In this channel, the He WDs produced first red giants (RGs) with degenerate cores via stable mass transfer and sdB stars RGs common-envelope (CE) ejection. They important for studies of CE evolution, binary population synthesis. However, relation between WD orbital period has not been specifically studied. paper, we use semi-analytic method follow their formation find...
Binary evolution theory predicts that the second common envelope (CE) ejection can produce low-mass (0.32-0.36 Msun) subdwarf B (sdB) stars inside ultrashort-orbital-period binary systems, as their helium cores are ignited under nondegenerate conditions. With orbital decay driven by gravitational-wave (GW) radiation, minimum periods of detached sdB binaries could be short ~20 minutes. However, only four with below an hour have been reported so far, while none them has period approaching...
Although multidimensional simulations have investigated the processes of double WD mergers, post-merger evolution only focused on carbon-oxygen (CO) or helium (He) merger remnants. In this work, we investigate for first time remnants stemmed from oxygen-neon (ONe) WDs with CO WDs. Our simulation results indicate that can evolve to hydrogen- and helium-deficient giants maximum radius about 300Rsun. models show evidence more massive than 1.95Msun ignite Ne before significant mass-loss ensues,...
Double white dwarf (WD) merger process and their post-merger evolution are important in many fields of astronomy, such as supernovae, gamma-ray bursts, gravitational waves, etc. The evolutionary outcomes double ultra-massive WD remnants still a subject debate, though the general consensus is that remnant will collapse to form neutron star. In this work, we investigate 2.20Msun stemmed from coalescence 1.10Msun ONe WDs. We find ignites off-centre neon burning at position near surface primary...
Over the past few years, wide-field time-domain surveys like ZTF and OGLE have led to discoveries of various types interesting short-period stellar variables, such as ultracompact eclipsing binary white dwarfs, rapidly rotating magnetised dwarfs (WDs), transitional cataclysmic variables between hydrogen-rich helium accretion, blue large-amplitude pulsators (BLAPs), which greatly enrich our understandings physics under some extreme conditions. In this paper, we report first-two-year (i.e.,...
Abstract Binary evolution theory predicts that the second common envelope (CE) ejection can produce low-mass (0.32-0.36 M⊙) subdwarf~B (sdB) stars inside ultrashort-orbital-period binary systems as their helium cores are ignited under nondegenerate conditions. With orbital decay driven by radiation of gravitational waves, minimum period an sdB formed in this channel reach before Roche-lobe overflow is ~20 minutes. However, only four binaries with periods below hour have been reported so far,...