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The minimum variation timescale (MVT) of soft gamma-ray repeaters can be an important probe to estimate the emission region in pulsar-like models, as well as the Lorentz factor and radius of the possible relativistic jet in gamma-ray burst (GRB)-like models, thus revealing their progenitors and physical mechanisms. In this work, we systematically study the MVTs of hundreds of X-ray bursts (XRBs) from SGR J1935+2154 observed by {\it Insight}-HXMT, GECAM and Fermi/GBM from July 2014 to Jan 2022 through the Bayesian Block algorithm. We find that the MVTs peak at $\sim$ 2 ms, corresponding to a light travel time size of about 600 km, which supports the magnetospheric origin in pulsar-like models. The shock radius and the Lorentz factor of the jet are also constrained in GRB-like models. Interestingly, the MVT of the XRB associated with FRB 200428 is $\sim$ 70 ms, which is longer than that of most bursts and implies its special radiation mechanism. Besides, the median of MVTs is 7 ms, shorter than the median MVTs of 40 ms and 480 ms for short GRBs or long GRBs, respectively. However, the MVT is independent of duration, similar to GRBs. Finally, we investigate the energy dependence of MVT and suggest that there is a marginal evidence for a power-law relationship like GRBs but the rate of variation is at least about an order of magnitude smaller. These features may provide an approach to identify bursts with a magnetar origin., accepted for publication in ApJS

In this paper, we presented the 23.3 years of pulsar timing results of PSR J1456-6413 based on the observation of Parkes 64m radio telescope. We detected two new glitches at MJD 57093(3) and 59060(12) and confirmed its first glitch at MJD 54554(10). Using the "Cholesky" timing analysis method, we have determined its position, proper motion, and two-dimensional transverse velocities from the data segments before and after the second glitch, respectively. Furthermore, we detected exponential recovery behavior after the first glitch, with a recovery time scale of approximately 200 days and a corresponding exponential recovery factor Q of approximately 0.15(2), while no exponential recovery was detected for the other two glitches. More interestingly, we found that the leading component of the integral pulse profile after the second glitch became stronger, while the main component became weaker. Our results will expand the sample of pulsars with magnetosphere fluctuation triggered by the glitch event.

HS 2325+8205 is a long-period eclipsing dwarf nova with an orbital period above the period gap (Porb>3 h) and is reported to be a Z Cam-type dwarf nova. Based on the photometry of the Transiting Exoplanet Survey Satellite (TESS), the light variation and the quasi-periodic oscillation (QPOs) of HS 2325+8205 are studied. Using Continuous Wavelet Transform (CWT), Lomb-Scargle Periodogram (LSP), and sine fitting methods, we find for the first time that there is a QPOs of ~ 2160s in the long outburst top light curves of HS 2325+8205. Moreover, we find that the oscillation intensity of the QPOs of HS 2325+8205 is related to the orbital phase, and the intensity in orbital phases 0.5-0.9 are stronger than in orbital phases 0.1-0.5. Therefore, the relationship between the oscillation intensity of QPOs and the orbital phase may become a research window for the origin of QPOs. In addition, we use the LSP to correct the orbital period of HS 2325+8205 as 0.19433475(6) d.

NSVS 10441882 is a newly discovered eclipsing binary system with strong magnetic activity and an orbital period of ∼ 0.5166 days. In order to study this eclipsing binary system, we analyzed its first four-color (BVRcIc) light curves. The observed light curves were asymmetric, so we used the 2013 version of the Wilson–Devinney (W–D) program with cool star-spots to analyze these data. We discovered that NSVS 10441882 is a detached total eclipsing binary system with an orbit inclination of 85°.34 ± 0.07 and a mass ratio of q = 0.94 ± 0.03. Based on the CCD times of the light minima according to our observations and those reported previously, the orbital period changes of NSVS 10441882 were studied using the traditional O–C method for the first time. The O–C diagram of the target exhibited a cyclic oscillation with a period of 16.7 ± 0.20 years and an amplitude of 0.00349 ± 0.00029 days, probably due to the presence of an unseen third body. If we assume that the total mass of NSVS 10441882 is 1.3M⊙ (according to our calculated results for the average color index and mass ratio), then the mass of the third body is no less than 0.12 ± 0.01 M⊙. Moreover, the orbital evolution of the central system will be accelerated due to the presence of this additional component.

Multiwavelength observation is an effective way to test and constrain theoretical models of pulsars. X-ray observations reveal that the light curve of the Crab pulsar has two sharp peaks, with a phase separation of ~ 0.4 spin periods between its first peak (P1) and second peak (P2). Using observations from the Hard X-ray Modulation Telescope (Insight-HXMT) of China, we studied eight-wavelength (from 11 keV to 250 keV) X-ray light curves of the Crab pulsar and found that the phase separation has no significant trend with the energy, while the total intensity ratios of the P2 and bridge emission components to the P1 component have a significant increasing trend with increasing energy. We used three-dimensional magnetospheric models for the core gap (CG) and annular gap (AG) to simulate the eight-wavelength X-ray light curves. It was found that the P1, P2 and bridge emission components at each band can be well reproduced by the two models and that the P1 and P2 emissions could be generated in the AG region, whereas the bridge emission could be generated in the CG region.

Using the public material of the Rosse X-ray Timing Explorer (RXTE) satellite from January 1996 to May 2005, the periodicity of the light curve of the X-ray binary Cyg X-1 as a black hole candidate is studied and some interesting periods ( T = 1.0 ± 0.2 d and T = 18.0 ± 3.0 d) are found. In the hard state, both the periods T = 1.0 ± 0.2 d and T = 18.0 ± 3.0 d simultaneously appear in the light curve, while in the soft state only the period T = 1.0 ± 0.2 d exists. For analyzing the same material, a new method (i.e., the “derivative” method) is introduced and, in order to check the validity of this method, two traditional methods (the fast Fourier transform and period folding method) are also applied. Identical results are obtained. Besides, the orbital period of Cyg X-1 is also probed. It is discovered that the orbital period T = 5.6 d appears not only in the hard state, but also in the soft state, while it is more obvious in the former.