We present the first results of an ensemble and systematic survey of oscillation mode variability in pulsating hot B subdwarf (sdB) and white dwarf stars observed with the original Kepler mission. The satellite provides uninterrupted high-quality photometric data with a time baseline that can reach up to 4 yr collected on pulsating stars. This is a unique opportunity to characterize long-term behaviors of oscillation modes. A mode modulation in amplitude and frequency can be independently inferred by its fine structure in the Fourier spectrum, from the sLSP, or with prewhitening methods applied to various parts of the light curve. We apply all these techniques to the sdB star KIC 3527751, a long-period-dominated hybrid pulsator. We find that all the detected modes with sufficiently large amplitudes to be thoroughly studied show amplitude and/or frequency variations. Components of three identified quintuplets around 92, 114, and 253 μHz show signatures that can be linked to nonlinear interactions according to the resonant mode coupling theory. This interpretation is further supported by the fact that many oscillation modes are found to have amplitudes and frequencies showing correlated or anticorrelated variations, a behavior that can be linked to the amplitude equation formalism, where nonlinear frequency corrections are determined by their amplitude variations. Our results suggest that oscillation modes varying with diverse patterns are a very common phenomenon in pulsating sdB stars. Close structures around main frequencies therefore need to be carefully interpreted in light of this finding to secure a robust identification of real eigenfrequencies, which is crucial for seismic modeling. The various modulation patterns uncovered should encourage further developments in the field of nonlinear stellar oscillation theory. It also raises a warning to any long-term project aiming at measuring the rate of period change of pulsations caused by stellar evolution, or at discovering stellar (planetary) companions around pulsating stars using timing methods, as both require very stable pulsation modes.

Cosmic ray (CR) physics has entered a precision-driven era. With the latest AMS-02 nuclei data (boron-to-carbon ratio, proton flux, helium flux, and antiproton-to-proton ratio), we perform a global fitting and constrain the primary source and propagation parameters of cosmic rays in the Milky Way by considering 3 schemes with different data sets (with and without $\overline{\mathrm{p}}/\mathrm{p}$ data) and different propagation models (diffusion-reacceleration and diffusion-reacceleration-convection models). We find that the data set with $\overline{\mathrm{p}}/\mathrm{p}$ data can remove the degeneracy between the propagation parameters effectively and it favors the model with a very small value of convection (or disfavors the model with convection). The separated injection spectrum parameters are used for proton and other nucleus species, which reveal the different breaks and slopes among them. Moreover, the helium abundance, antiproton production cross sections, and solar modulation are parametrized in our global fitting. Benefited from the self-consistence of the new data set, the fitting results show a little bias, and thus the disadvantages and limitations of the existed propagation models appear. Comparing to the best fit results for the local interstellar spectra ($\varphi =0$) with the VOYAGER-1 data, we find that the primary sources or propagation mechanisms should be different between proton and helium (or other heavier nucleus species). Thus, how to explain these results properly is an interesting and challenging question.

Recently, DAMPE has released its first results on the high-energy cosmic-ray electrons and positrons (CREs) from about 25 GeV to 4.6 TeV, which directly detect a break at $\sim 1\mathrm{TeV}$. This result gives us an excellent opportunity to study the source of the CREs excess. In this work, we used the data for proton and helium flux (from AMS-02 and CREAM), $\overline{\mathrm{p}}/\mathrm{p}$ ratio (from AMS-02), positron flux (from AMS-02) and CREs flux (from DAMPE without the peak signal point at $\sim 1.4\mathrm{TeV}$) to do global fitting simultaneously, which can account for the influence from the propagation model, the nuclei and electron primary source injection, and the secondary lepton production precisely. For an extra source to interpret the excess in lepton spectrum, we consider two separate scenarios (pulsar and dark matter annihilation via leptonic channels) to construct the bump ($\gtrsim 100\mathrm{GeV}$) and the break at $\sim 1\mathrm{TeV}$. The result shows that (i) in the pulsar scenario, the spectral index of the injection should be ${\nu }_{\mathrm{psr}}\sim 0.65$ and the cut-off should be $R_c\sim 650\mathrm{GV}$; (ii) in dark matter scenario, the dark matter particle’s mass is $m_{\chi }\sim 1208\mathrm{GeV}$, and the cross section is $⟨\sigma v⟩\sim 1.48\times {10}^{-23}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$. Moreover, in the dark matter scenario, the $\tau \overline{\tau }$ annihilation channel is highly suppressed, and a DM model is built to satisfy the fitting results.

Bi-site time-series photometric and high-resolution spectroscopic observations were made for the double-mode high-amplitude δ Scuti star VX Hya. The fundamental frequency f ₀ = 4.4763 c days⁻¹, the first overtone f ₁ = 5.7897 c days⁻¹, and 23 harmonics and linear combinations of f ₀ and f ₁ are detected by pulsation analysis. From the spectroscopic data, we get [Fe/H] = −0.2 ± 0.1 dex. The period change rate of the fundamental mode is obtained by using the Fourier-phase diagram method, which gives the value of . With these results from the observations, we perform theoretical explorations with the stellar evolution code MESA, and constrain the models by fitting f ₀, f ₁, and (1/P ₀)(dP ₀/dt) within 3σ deviations. The results show that the period change of VX Hya could be ascribed to the evolutionary effect. The stellar parameters of VX Hya could be derived as: the mass 2.385 ± 0.025 M _⊙, the luminosity log(L/L _⊙) = 1.93 ± 0.02, and the age (4.43 ± 0.13) × 10⁸ years. VX Hya is found to locate at the post-main-sequence stage with a helium core and a hydrogen-burning shell on the H–R diagram.