arXiv subjects

Wen-Shi Tang

Publications and source records attributed to Wen-Shi Tang.

4 recordsLinked to original sources

arXiv2026

The Influence of Evaporation on the Formation and Evolution of Huntsman Systems

Huntsman systems are a recently identified and rare subclass of millisecond pulsar (MSP) binaries, characterized by a detached neutron star and an evolved giant companion in relatively wide orbits. Their formation has been proposed to involve red-bump-induced detachment, whereas the influence of MSP-driven evaporation during this evolutionary stage has not yet been quantitatively assessed. We quantify the influence of MSP-driven evaporation on the formation and evolution of Huntsman systems and assess its effects on their observable properties. We performed detailed binary evolution calculations including MSP-driven evaporation over a wide range of initial binary parameters and combined them with binary population synthesis to predict the observable population of Huntsman systems. We find that Huntsman systems originate primarily from binaries undergoing Case B mass transfer and red-bump-induced detachment, with initial donor masses of $1.0-2.5\ M_\odot$ and orbital periods above the bifurcation period. Evaporation has a secondary effect, slightly modifying the orbital evolution and the duration of the detached phase, but does not significantly alter the formation parameter space or the expected population, which contains about 10 Huntsman systems. We further show that evaporation can produce systematic shifts in the white dwarf mass-orbital period relation at the low-mass end, leading to systematically wider final orbits for a given white dwarf mass.

astro-ph.SR↗

arXiv2026

The Evolution of Cataclysmic Variables Under Various Magnetic Braking Prescriptions

Recent studies revealed discrepancies between observations and the predictions of the standard magnetic braking (MB). Although alternative models have been broadly discussed in neutron star binaries, they have not been systematically tested in cataclysmic variables (CVs). In this work, we investigate the performance of four MB models in CVs: the standard MB, the Convection And Rotation Boosted (CARB) model, the $\tau$-boosted model, and the saturated, boosted, and disrupted (SBD) model. We find that both the CARB and $\tau$-boosted models appear too strong so that it fails to reproduce the location of the period gap in CVs, indicating that they are not appropriate for CVs. Furthermore, we present a comparison between the standard MB and the SBD models. Compared with the standard model, although the SBD model can better reproduce some observational features, it also exacerbates certain discrepancies between theory and observations. We also find that different prescriptions for the convective turnover timescale have a significant impact on the results in the non-standard MBs. Finally, we discuss the impact of the SBD model on the formation and evolution of AM CVn.

astro-ph.HE↗

arXiv2024

Evolution of Cataclysmic Variables with Binary-Driven Mass-Loss during Nova Eruptions

The discrepancies between observations and theoretical predictions of cataclysmic variables (CVs) suggest that there exists unknown angular momentum loss mechanism(s) besides magnetic braking and gravitational radiation. Mass loss due to nova eruptions belongs to the most likely candidates. While standard theory assumes that mass is lost in the form of radiation driven, optically thick wind (fast wind; FW), recent numerical simulations indicate that most of the mass loss is initiated and shaped by binary interaction. We explore the effect of this binary-driven mass-loss (BDML) on the CV evolutions assuming a major fraction of the lost mass leaves the system from the outer Lagrangian point. Different from the traditional continuous wind picture, we consider the mass loss process to be instantaneous, because the duration of nova eruptions is much shorter than the binary evolutionary timescale. Our detailed binary evolution calculations reveal the following results. (1) BDML seems able to provide extra angular momentum loss below the period gap. The mass transfer rates at a given orbital period occupy a large range, in agreement with the observed secular mass transfer rate distribution in CVs. (2) The enhanced mass transfer rates do not lead to runaway mass transfer process, and allow the white dwarfs to grow mass $\lesssim 0.1\,M_{\odot}$. (3) BDML can cause both positive and negative variations of the orbital period induced by nova eruptions, in line with observations, and can potentially explain the properties of some peculiar supersoft X-ray sources likely CAL 87, 1E 0035.4$-$7230, and RX J0537.7$-$7034.

astro-ph.HE↗

arXiv2022

Impact of Asymmetrical Mass Ejection from Proto-White Dwarfs on the Properties of Binary Millisecond Pulsars

The standard formation theory of binary millisecond pulsars (BMSPs) predicts efficient orbital circularization due to tidal interaction during the previous mass transfer phase. Therefore, BMSPs are expected to have a circular orbit. However, the discovery of several eccentric BMSPs (eBMSPs) with a white dwarf (WD) companion has challenged this picture. In particular, recent observation reveals that the spin angular momentum of the eBMSP J0955$-$6150 is tilted at an angle $>4.8^{\rm \degree}$ from the orbital angular momentum. This is the first time that a tilt angle is deduced for eBMSPs, which provides an important clue to their formation mechanism. Both the orbital eccentricity and tilt angle could be qualitatively accounted for by asymmetrical mass ejection during thermonuclear flashes from proto-WDs (so-called the thermonuclear rocket model), but detailed studies are still lacking. In this paper, we simulate the impact of the kick caused by asymmetrical mass ejection on the properties of BMSPs. We find that the thermonuclear rocket model can potentially explain the observational characteristics of both eBMSPs and normal BMSPs under reasonable input parameters. In addition, our results predict a wide range of the orbital period (from less than one day to more than several hundred days) for eBMSPs, which can be tested by future observations.

astro-ph.HE↗