arXiv subjects

Wen-Ping Liao

Publications and source records attributed to Wen-Ping Liao.

At least 19 recordsLinked to original sources

arXiv2026

Superoutbursts and Superhumps of Cataclysmic Variables observed with TESS

Superoutbursts and superhumps are characteristic signatures of SU UMa-type cataclysmic variables, yet the full diversity of superhump evolutionary behaviour remains poorly constrained owing to the limitations of ground-based photometric monitoring. Here we report a systematic analysis of 30 SU UMa-type dwarf novae observed with the Transiting Exoplanet Survey Satellite, covering 37 superoutburst events. We detect coherent superhump signals in 29 systems-including five first-time detections-and determine or refine orbital periods for 13 objects. The high-cadence light curves clearly resolve the canonical three-stage (A-B-C) superhump period evolution. Using Stage A periods, we derive dynamical mass ratios for 18 systems, consistent with established cataclysmic variable evolutionary tracks. The measured Stage B period derivatives match the range of values from ground-based campaigns, with prominent positive drifts concentrated in short-period, low-mass-ratio systems. Repeated superoutbursts yield consistent evolutionary patterns, demonstrating that superhump morphology is an intrinsic, repeatable property. Two systems break the standard template: RZ LMi shows an inverted stage sequence inconsistent with classical precession theory, while ASASSN-14kj exhibits no stage evolution but a coherent long-period modulation. Persistent superhumps during normal outbursts in three systems provide direct evidence that eccentric disk structures can survive beyond their parent superoutbursts, revealing a decoupling between thermal accretion and tidal eccentricity cycles. These results demonstrate the power of space-borne photometry for probing accretion disk dynamics and testing precession models across the cataclysmic variable parameter space.

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arXiv2026

Eclipse Properties and Superhump Evolution in the SU UMa-Type Dwarf Nova Z Cha

The advent of large-scale time-domain surveys provides both opportunities and challenges for understanding accretion disk evolution in cataclysmic variables (CVs). Using high-cadence photometry from the Transiting Exoplanet Survey Satellite (TESS), we investigate the eclipsing SU UMa-type dwarf nova Z Cha. Leveraging eclipses as a natural probe, we examine the evolution of the accretion disk through variations in eclipse depth, O--C of eclipse minima, and positive superhump (PSH) amplitude. During superoutbursts, all three quantities exhibit quasi-periodic modulations with a common period of $\sim$2 days, consistent with the precession period of an eccentric disk. We interpret these correlated variations as evidence of an eccentric, precessing disk: O--C traces the periodic shift of the system's brightness center, while eclipse depth and PSH amplitude vary with the orientation of the disk bulge relative to the line of sight. In quiescence (Sectors 13 and 93), PSHs with periods of $\sim$0.0762 days show linearly decreasing amplitudes and periods, indicating gradual shrinkage of the eccentric disk and a slowing precession. Remarkably, a coherent signal with a period of $\sim$0.0729~days ($ε^{-}\approx-0.02$) appears in the same quiescent intervals. This signal may represent negative superhumps (NSHs) coexisting with PSHs, although an orbital sideband of the PSH cannot presently be excluded with the available data. If confirmed as NSHs, their coexistence with PSHs would challenge the classical tilted-disk model, and could be explained by retrograde apsidal precession of an eccentric disk, where the inner disk precesses retrogradely (NSHs) and the outer disk progradely (PSHs); this interpretation remains to be tested by further observations.

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arXiv2026

KIC 6464285: A Solar-type Eclipsing Binary in a Hierarchical Triple System with Quasi-periodic Out-of-eclipse Modulations

We present the first detailed analysis of the solar-type triple system KIC 6464285. Combining long-term, high-precision photometry from Kepler, TESS, and ZTF with low-resolution spectra from LAMOST and near-infrared high-resolution spectra from SDSS/APOGEE, we performed a joint analysis of the light curves, eclipse timing variations (ETVs), and radial velocities. Spectroscopic analysis reveals the system to be triple-lined, with the inner binary's primary being a G-type main-sequence star and a mass ratio of $0.627(7)$. Light curve modeling indicates that the inner binary is detached, with filling factors of approximately 26\% and 11\% for the primary and secondary, respectively, and a tertiary light contribution of about 27\%. ETV analysis shows a significant light-travel-time effect (LTTE), consistent with the presence of the tertiary companion, whose minimum mass is estimated as $M_{3,\rm min}=0.74(1)~M_\odot$. The light curve exhibits a pronounced O'Connell effect and quasi-periodic variations, indicative of starspot activity modulating the photometry on a $\sim$131-day timescale. Kepler observations further reveal 30 superflares, each with total energies exceeding $10^{34}$ erg. This study presents detailed observational constraints on the orbital configuration, stellar properties, and magnetic activity of KIC 6464285, providing a benchmark for studies of hierarchical triple systems.

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arXiv2026

Two Potential Exoplanets around A-type Stars Selected from 18 Planetary Candidates

We screen and analyze exoplanet candidates around A-type stars (defined as Teff between 7500 and 10,000 K) observed by the Transiting Exoplanet Survey Satellite to evaluate their likelihood of being genuine exoplanets. Our analysis involves transit signal searches, light-curve detrending, estimation of nearby-source contamination, and calculation of false-positive probabilities (FPPs). Among the 18 candidates analyzed, four exhibit relatively low FPP values (<15%). Two candidates are excluded from further analysis due to the lack of stellar parameter data. Six candidates show no clearly detectable transit signals, likely due to shallow or weak features, while six candidates exhibit relatively high FPP values, leaving their authenticity uncertain. Among the four low-FPP targets, two-TIC 48031665 and TIC 259230140-stand out as the most promising. TIC 48031665 shows a very shallow transit signal but has a very low FPP and minimal nearby starlight contamination. TIC 259230140 displays a clear U-shaped transit light curve typical of planetary transits, along with slightly higher yet still low FPP and contamination levels. These two objects are therefore considered the most promising candidates identified in this study.

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arXiv2026

SZ Lyncis: A Non-Accreting Neutron Star-delta Scuti Binary Candidate Discovered via Dynamics and Asteroseismology

Neutron stars (NSs) are traditionally discovered through radio, X-ray, or gamma-ray observations, but optical time-domain surveys can unveil non-accreting NSs in wide binaries. Here we report a NS candidate in the single-lined binary SZ~Lyncis, identified through a combination of asteroseismology, spectroscopy, pulsation timing, and astrometry. The visible $δ$ Scuti primary has a mass of $M_1 = 1.83_{-0.01}^{+0.06}~\mathrm{M_{\odot}}$ from asteroseismic modeling. With the orbital inclination ($i = 38.67 \pm 0.29^\circ$) from the astrometric data of Gaia and Hipparcos, we obtain companion masses of $M_2 = 1.76_{-0.042}^{+0.042}~\mathrm{M_{\odot}}$ (radial velocity) and $M_2 = 2.07_{-0.045}^{+0.045}~\mathrm{M_{\odot}}$ (timing variations). The companion's mass exceeds the Chandrasekhar limit and lies in the NS range. Multiple arguments rule out alternatives: the astrometric mass function and the spectral energy distribution, which shows no extra light, together exclude any luminous companion; the mass and lack of Balmer absorption rule out white dwarfs (WDs); the system's age ($1.25$~Gyr) disfavors a double WD; and the mass is too low for a black hole. The wide, low-eccentricity orbit and absence of accretion signatures are consistent with a quiescent NS. SZ~Lyn has the potential to be the first $δ$ Scuti binary with a NS candidate identified through asteroseismology and dynamics, demonstrating the potential of this approach to uncover non-accreting compact objects.

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arXiv2025

Tidally Trapped Two-pole Pulsations Discovered in a Close Binary with a Massive $β$ Cephei Star

Tidally tilted pulsators (TTPs), whose pulsation axis aligns with the binary's semi-major axis, represent a newly established class of oscillators in binary systems. While all previously known TTPs are either $δ$ Scuti or subdwarf B-type stars, their existence has remained unidentified in more massive $β$ Cephei variables. Here, we report the discovery of tidally trapped pulsations in the massive ellipsoidal variable HD~329379, based on photometry from the Transiting Exoplanet Survey Satellite (TESS). Our analysis reveals a $β$ Cephei pulsator in a 2.25-day orbit whose pulsation mode amplitude is strongly modulated with the orbital frequency. Based on our analysis, we concluded that this modulation can be explained by pulsations with significantly larger amplitude near the star's two tidal poles (apsides). We interpret this as a tidally distorted quadrupole pulsation chariacteristiced by trapped two-pole pulsations, with a pulsation axis aligned with the tidal axis. This represents the first identification of such a pulsation mode in a $β$ Cephei star, which differs from single-sided pulsations observed in previous works, marking a rare and important discovery. Our work extends the family of TTPs beyond $δ$ Scuti and subdwarf B-type stars to include more massive $β$ Cephei variables. In particular, the two-pole pulsator HD~329379 stands out as the prototype of a new class of TTPs in massive stars. These results not only provide a new insight to probe the interior structure and evolutionary state for massive stars but also offer a unique opportunity to study the interaction between pulsations and strong tidal distortions.

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arXiv2025

Asteroseismology and Dynamics Reveal Interior Structure and Coeval Evolution in the Triply Post-Main-Sequence system DG Leo

$δ$ Scuti stars in binary or multiple systems serve as crucial probes for studying stellar pulsation and evolution. However, many such systems are not ideal for asteroseismology due to uncertainties in mass transfer with close companions and the challenges of dynamically measuring all components' physical properties. The triple system DG~Leo, comprising an inner binary and a distant $δ$ Scuti star, is an ideal target due to its well-separated pulsator. By combining new \textit{TESS} photometry with archival spectroscopy, our dynamical analysis shows that the system's three components share similar masses, radii, and luminosities within errors, occupying coincident Hertzsprung--Russell diagram positions, indicative of coeval evolution. By fitting seven observed $δ$ Scuti frequencies through asteroseismic modeling with dynamically constrained theoretical grids, we simultaneously trace the pulsating star's evolution and constrain the triple system's evolutionary stage, with the derived fundamental parameters showing consistency with the dynamical solutions. Our analysis reveals that all three components of DG~Leo are in the post-main-sequence phase, with a system age of $0.7664^{+0.1402}_{-0.1258}$~Gyr. Additionally, the $δ$ Scuti component shows multiple non-radial modes with significant mixed-character frequencies, providing precise constraints on its convective core extent ($R_{\mathrm{cz}}/R = 0.0562^{+0.0137}_{-0.0021}$).

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arXiv2025

Orbital and Pulsation Analysis of 42 Heartbeat Stars Discovered in TESS Data

Heartbeat stars (HBSs) are ideal laboratories for studying the formation and evolution of binary stars in eccentric orbits and their mutual tidal interactions. We present 42 new HBSs discovered based on TESS-SPOC and QLP data. Their physical parameters have been obtained through modeling with appropriate models. Subsequently, Tidally excited oscillations (TEOs) are detected in ten systems, and their pulsation phases and modes are identified. Most pulsation phases can be explained by the dominant being spherical harmonic degree $l=2$ and azimuthal order $m=0$ or $\pm2$. For TIC 156846634, the harmonic with large deviation ($>3σ$) from the expected adiabatic phase can be expected to be a traveling wave or significantly nonadiabatic. The harmonic numbers $n$ = 16 in TIC 184413651 may not be considered as a TEO candidate due to its large deviation ($>2σ$) from the adiabatic expectation. Moreover, TIC 92828790 shows no TEOs but exhibits a significant $γ$\,Dor-type pulsation. The eccentricity-period ($e-P$) relation also shows a positive correlation between eccentricity and period, as well as the existence of orbital circularization. The Hertzsprung-Russell diagram shows that TESS HBSs have higher temperatures and greater luminosities than Kepler HBSs, possibly due to selection effects. This significantly enhances the detectability of massive HBSs and those containing TEOs.

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arXiv2025

Heartbeat Stars Recognition Based on Recurrent Neural Networks: Method and Validation

Since the variety of their light curve morphologies, the vast majority of the known heartbeat stars (HBSs) have been discovered by manual inspection. Machine learning, which has already been successfully applied to the classification of variable stars based on light curves, offers another possibility for the automatic detection of HBSs. We propose a novel feature extraction approach for HBSs. First, the orbital frequencies are calculated automatically according to the Fourier spectra of the light curves. Then, the amplitudes of the first 100 harmonics are extracted. Finally, these harmonics are normalized as feature vectors of the light curve. A training data set of synthetic light curves is constructed using ELLC, and their features are fed into recurrent neural networks (RNNs) for supervised learning, with the expected output being the eccentricity of these light curves. The performance of the RNNs is evaluated using a test data set of synthetic light curves, achieving 95$\%$ accuracy. When applied to known HBSs from the OGLE, Kepler, and TESS surveys, the networks achieve an average accuracy of 86$\%$. This method successfully identifies four new HBSs within the eclipsing binary catalog of Kirk et al. The use of orbital harmonics as features for HBSs proves to be a practical approach that significantly reduces the computational cost of neural networks. RNNs show excellent performance in recognizing this type of time series data. This method not only allows efficient identification of HBSs but can also be extended to recognize other types of periodic variable stars.

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arXiv2025

V455 Car: an oscillating eclipsing Algol-type binary in triple star system

V455 Car is a southern oscillating eclipsing Algol-type system with an orbital period of 5.132888 days. Our first photometric solutions based on the Transiting Exoplanet Survey Satellite indicate that it is a semi-detached binary with the secondary star is almost filling its Roche lobe. The noticeable O'Connell effect in light curve could be explained by hot spot on the primary component, which may be attributed to the mass transfer from the secondary component to the primary one. The absolute parameters are determined as: $M_{1} = 5.30 \pm 1.10 \, \rm M_{\odot}$, $R_{1} = 3.17 \pm 0.22 \, \rm R_{\odot}$ for the primary, and $M_{2} = 1.58 \pm 0.32 \, \rm M_{\odot}$, $R_{2} = 6.66 \pm 0.46 \, \rm R_{\odot}$ for the secondary. \textbf{Based on $O-C$ analysis, we find a periodic variation of $P_3=26.62(\pm1.66)\,yr$. The periodic oscillation suggests a possible third body with a minimal mass of $0.59(\pm0.13)\,\rm M_{\odot}$}. It is speculated that the secondary star has undergone a longer evolution, leading to a mass ratio reversal being experienced in the binary system. Our frequency analysis finds that the primary of V455 Car may be an SPB/SLF star. This study reports a novel example of an oscillating eclipsing Algol-type system featuring an SPB/SLF primary star and a red giant star, which suggest that strong observational results for a high incidence of third bodies in massive binaries.

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arXiv2025

Comprehensive Parameter Determination of Exoplanet through Asteroseismic Host Star Constraints

This study develops a robust framework for exoplanet characterization by leveraging asteroseismic constraints on host stars. Using precise photometric data from missions such as \textit{Kepler} and \textit{TESS}, we derive stellar parameters, including mass, radius, and age, with high accuracy through asteroseismic analysis. These stellar parameters are incorporated as priors in a Bayesian framework to refine planetary properties such as mass, radius, and orbital parameters. By applying Markov Chain Monte Carlo (MCMC) methods, we extract posterior distributions of planetary parameters, achieving significant improvements in precision and reliability. This approach is particularly effective for systems with evolved host stars, where precise stellar properties are essential for resolving uncertainties in planetary characterization. The results demonstrate the importance of asteroseismology in bridging stellar astrophysics and exoplanet science, enabling detailed studies of planetary system architectures and their dependence on host star properties. Our methodology underscores the synergy between stellar and planetary studies, paving the way for future research on exoplanet populations. This work provides a foundation for utilizing data from upcoming missions like \textit{PLATO}, ensuring continued advancements in the precision and scope of exoplanet characterization.

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arXiv2024

KIC 7914906: An Eclipsing Heartbeat Star with Tidally Excited Oscillations and Gamma Doradus/Delta Scuti Hybrid Pulsations

We present the eclipsing Heartbeat Star KIC 9704906 with tidally excited oscillations (TEOs) and gamma Doradus/delta Scuti hybrid pulsations. The derived parameters show that it has an orbital period of $P$=8.7529108(1) days, a high eccentricity of $e$=0.467(3), and a high inclination of $i$=78$^{\circ}$.81(6). The mass ratio $q$=0.981(5), the relative radii (radius divided by semi-major axis) $r_1$=0.0639(2), and $r_2$=0.0715(4) indicate that the secondary component has a less mass and a larger radius, and may have evolved off the main sequence. The eight derived TEO candidates, $n$ = 3, 4, 5, 6, 7, 12, 40, and 44 harmonics, are consistent with or close to the dominant spherical harmonic $l=2$, $m=0$, or $\pm2$, assuming that the spin and orbital axes are aligned, and the pulsations are adiabatic and standing waves. We also identify ten independent frequency candidates, but one of them, $\mathit{f_{7}}$, is more like a modulation of a quasi-periodic signal and the orbits. According to the g-mode frequencies, we find that the rotation period of one component is 11.52(29) days. Although the masses and radii cannot be further constrained due to the lack of sufficient high-precision spectra, the fascinating phenomena in the Fourier spectra are evident and valuable in this system.

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arXiv2024

Decoding the Future of Exoplanets: Asteroseismic Confirmation of Subgiant and Red Giant Hosts

Asteroseismology has emerged as a powerful tool to unravel the intricate relationships between evolved stars and their planetary systems. In this study, we leverage this technique to investigate the evolutionary stages of five exoplanet host stars, each exhibiting solar-like oscillations. Building on our previous work that identified two host stars as red clump and red giant branch (RGB) stars, this study focuses on a new and broader sample. By precisely measuring asteroseismic parameters such as the period spacing of dipole gravity modes ($ΔΠ_{1}$), we provide definitive confirmation of these stars' evolutionary states as subgiants or RGB stars. These results are not only crucial for understanding the internal structures of evolved stars but also for predicting the eventual fate of their planetary companions, which may face engulfment as their host stars expand. This research highlights the profound role of asteroseismology in advancing our knowledge of planetary system evolution and opens new pathways for exploring how stellar evolution impacts planetary survival. Our findings set the stage for future studies on the dynamic fates of exoplanets, providing key insights into the intricate processes of stellar and planetary evolution.

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arXiv2024

CZ Aqr: an oscillating eclipsing Algol-type system composed of a $δ$ Sct primary star and a subgiant star in a quadruple system

Eclipsing Algol-type systems containing a $δ$ Scuti (hereafter $δ$ Sct) star enable precise determination of physical parameters and the investigation of stellar internal structure and evolution. We present the absolute parameters of CZ Aquarius (hereafter CZ Aqr) based on TESS data. CZ Aqr has an orbital period of 0.86275209 d, a mass ratio of 0.489 (6), and the secondary component nearly fills its Roche lobe. $O-C$ analysis reveals a downward parabolic trend and a cyclical variation with a period of 88.2 yr. The downward parabola suggests a long-term decrease in the orbital period with $\dot{P}$ = -3.09$\times$$10^{-8}$ d $\textrm{yr}^{-1}$. The mass loss rate is estimated to be 4.54$\times$$10^{-9}$ M$_{\odot}$ $\textrm{yr}^{-1}$, which possibly due to magnetic stellar wind or hot spot. The cyclical variation might be caused by the light travel time effect via the presence of a third body with a minimum mass of $M_{3min}$ = 0.312 (21) M$_{\odot}$. Additionally, there are two possible celestial bodies in a 2:7 resonance orbit around CZ Aqr. The asymmetric light curve is explained by adding a hot spot on the surface of the primary star. After removing the binary model, 26 frequencies were extracted from TESS data. Two radial modes were newly identified among three possible independent frequencies. Our results show that the eclipsing Algol-type system is composed of a $δ$ Sct primary star and a subgiant star in a quadruple system.

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arXiv2024

Evolutionary states and triplicity of four massive semi-detached binaries with long-term decreasing orbital periods in the LMC

The massive semi-detached binary with a long-term decreasing orbital period may involve a rapid mass-transfer phase in Case A, and thus they are good astrophysical laboratories for investigating the evolution of massive binary stars. In this work, by using the long-term observational light curves from the OGLE project and other data in the low-metallicity LMC, four semi-detached massive binaries with long-term decreases in the orbital periods are detected from 165 EB-type close binaries. It is found that the more massive component in S07798 is filling its Roche lobe where the period decrease is caused by mass transfer from the primary to the secondary. However, the other three (S03065, S12631, S16873) are semi-detached binaries with a lobe-filling secondary where the mass transfer between the components should cause the period to increase if the angular momentum is conservative. The long-term period decreases in these three systems may be caused by the angular momentum loss. Additionally, the orbital periods of three systems (S03065, S07798, S16873) are detected to show cyclic variation with periods shorter than 11 years, which can be plausibly explained by the presence of close-in third bodies in these massive binaries. Based on all of these results, it is suggested that the detected four semi-detached binaries almost have multiplicity. The companion stars are crucial for the origin and evolution of these massive close binaries.

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arXiv2024

Twenty-three New Heartbeat Star Systems Discovered Based on TESS Data

Heartbeat stars (HBSs) are ideal astrophysical laboratories to study the formation and evolution of binary stars in eccentric orbits and the internal structural changes of their components under strong tidal action. We discover 23 new HBSs based on TESS photometric data. The orbital parameters, including orbital period, eccentricity, orbital inclination, argument of periastron, and epoch of periastron passage of these HBSs are derived by using a corrected version of Kumar et al.'s model based on the Markov Chain Monte Carlo (MCMC) method. The preliminary results show that these HBSs have orbital periods in the range from 2.7 to 20 days and eccentricities in the range from 0.08 to 0.70. The eccentricity-period relation of these objects shows a positive correlation between eccentricity and period, and also shows the existence of orbital circularization. The Hertzsprung-Russell diagram shows that the HBSs are not all located in a particular area. The distribution of the derived parameters suggests a selection bias within the TESS survey towards massive HBSs with shorter orbital periods, higher temperatures and luminosities. These objects are a very useful source to study the structure and evolution of eccentricity orbit binaries and to extend the TESS HBS catalog.

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arXiv2024

Five New Heartbeat Star Systems with Tidally Excited Oscillations Discovered Based on TESS Data

Heartbeat stars (HBSs) with tidally excited oscillations (TEOs) are ideal astrophysical laboratories for studying the internal properties of the systems. In this paper, five new HBSs exhibiting TEOs are discovered using TESS photometric data. The orbital parameters are derived using a corrected version of Kumar et al.'s model based on the Markov Chain Monte Carlo (MCMC) method. The TEOs in these objects are examined, and their pulsation phases and modes are identified. The pulsation phases of the TEOs in TIC 266809405, TIC 266894805, and TIC 412881444 are consistent with the dominant $l=2$, $m=0$, or $\pm2$ spherical harmonic. For TIC 11619404, although the TEO phase is close to the $m=+2$ mode, the $m = 0$ mode cannot be excluded because of the low inclination in this system. The TEO phase in TIC 447927324 shows a large deviation ($>2σ$) from the adiabatic expectations, suggesting that it is expected to be a traveling wave rather than a standing wave. In addition, these TEOs occur at relatively low orbital harmonics, and we cautiously suggest that this may be an observational bias. These objects are valuable sources for studying the structure and evolution of eccentricity orbit binaries and extending the TESS HBS catalog with TEOs.

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arXiv2024

Evidence for a close-in tertiary orbiting around the Algol-type system HZ Dra with tidal splitting and spots activities

We reported a cyclic variation of $O-C$ diagram with a semi-amplitude of 0.0033 days and a period of 1.05 years for the pulsating eclipsing binary HZ Dra. The cyclic variation can be explained by the light travel-time effect via the presence of a close-in third body orbiting around HZ Dra in an elliptical orbit with a maximum semi-major axis of 0.92 au. Based on the W-D code, the contribution of the third light to the total system is determined to be 29 $\%$, which is in agreement with the estimated value. Our light curve modelling indicates an evolving hot and cool spot on the surface of the primary and secondary components, respectively. Their positions are roughly symmetrical to the inner Lagrangian point L1, which could be used to explain the variation in the O$^{'}$Connell effect. Our frequency analysis detects 1 radial p-mode, 7 non-radial p-modes and 1 non-radial g-mode. In addition, a total of 6 multiplets are identified, spaced by the orbital frequency, which can be explained as a tidally split mode caused by the equilibrium tides of the close binary system with a circular orbit. These pulsating features suggest that the primary of HZ Dra is a $δ$ Scuti star, pulsating in both p- and g-mode and influenced by tidal forces.

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