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The kinematics of superluminal components in blazar 3C 454.3 are studied. Nine components are included: superluminal knots R1, R2, R3, R4, A, B, C and D (from Britzen et al. 2013) and C4 (from Pauliny-Toth 1998). We find that their kinematics derived from VLBI observations can be consistently interpreted in terms of a jet precession scenario with a period of about 14.5 yr. We discuss the model fits of their trajectory, distance from the core and apparent velocity. We show that the bulk Lorentz factor (in the range 4 to 15) derived for these components does not have any dependence on the phase of the precession (or position angle for ejection). The Lense-Thirring effect is assumed to interpret the precession of the jet nozzle. The results obtained for blazar 3C 454.3 are only suggestive. They are not unique and have yet to be tested, but they might be useful for understanding the kinematics of superluminal components in blazars and for disentangling different mechanisms and factors.

The interstellar medium, filling the vast space between stars, is a rich reservoir of molecular material ranging from simple diatomic molecules to more complex, astrobiologically important molecules such as vinylcyanide, methylcyanodiaccetylene, cyanoallene, etc. Interstellar molecular cyanoallene is one of the most stable isomers of methylcynoacetylene. An attempt has been made to explore the possibility of forming cyanoallene in interstellar space by radical-radical and radical-molecule interaction schemes in the gaseous phase. The formation of cyanoallene starting from some simple, neutral interstellar molecules and radicals has been studied using density functional theory. The reaction energies and structures of the reactants and products show that the formation of cyanoallene is possible in the gaseous phase. Both of the considered reaction paths are totally exothermic and barrierless, thus giving rise to a high probability of occurrence. Rate constants for each step in the formation process of cyanoallene in both the reaction paths are estimated. A full vibrational analysis has been attempted for cyanoallene in the harmonic and anharmonic approximations. Anharmonic spectroscopic parameters such as rotational constants, rotation-vibration coupling constants and centrifugal distortion constants have been calculated.

We study non-thermal emissions from cascade processes in accreting X-ray binary pulsars. In the framework of the magnetospheric gap model, we consider three photon fields, which are respectively from the polar cap of a pulsar, its surrounding accretion disk and a massive companion star with a circumstellar disk, to shield the gap. The gap-accelerated ultra-relativistic electrons emit high-energy photons via curvature radiation and an inverse Compton scattering process, in which part of these high-energy photons absorbed by interactions with the surrounding photon fields can facilitate the following electromagnetic cascades. We first carry out numerical calculations of the cascade processes in order to obtain the predicted emission spectra. As an example, we subsequently apply this model to reproduce observations of LS I +61° 303. We find that the results can fit observations ranging from hard X-ray to γ-ray bands. In particular, they can explain the spectral cutoff feature at a few GeV. Finally, we suggest that the emissions detected by the Fermi Large Area Telescope from X-ray binary pulsars originate in the magnetosphere region of the pulsar.

Recent observations have found that chromospheric spicules behave like Alfvénic fluctuations. Low-frequency Alfvén waves are predicted to partially reflect in the transition region that has a gradient in the Alfvén speed, thereby producing inward Alfvén waves, which may interact nonlinearly with outward Alfvén waves to generate Alfvénic turbulence. However, the signature of Alfvénic turbulence in the chromosphere has not yet been quantitatively analyzed with observations. Here we analyze some characteristics related to Alfvénic turbulence with the observations from Hinode/SOT. We decompose the height-time diagram of the transverse oscillations to separate the outward and inward propagating Alfvénic-like signals. The counter-propagating waves are found to have similar amplitude, period and phase speed, suggesting a state having an approximate balance in bi-directional energy fluxes. Counter-propagation of intensity oscillation with lower propagation speed is also presented, probably indicating the presence of slow mode waves. Moreover, we attempt to estimate the Elsässer spectra of the chromospheric turbulence for the first time. The relative fluctuations in the magnetic field may be measured as the local slope of wave-like shapes in spicules. The resulting low-frequency Elsässer power spectra look similar to each other without showing a dominant population, which confirms these counter-propagating low-frequency Alfvénic waves are in a state of balanced flux. These observational results are believed to help us better understand the nature of chromospheric turbulence as well as chromospheric heating.

Low-inclination near-earth asteroid (NEA) (297274) 1996 SK, which is also classified as a potentially hazardous asteroid, has a highly eccentric orbit. It was studied by multi-wavelength photometry within the framework of an NEA color survey at Lulin Observatory. Here, we report the finding of large color variation across the surface of (297274) 1996 SK within one asteroidal rotation period of 4.656 ± 0.122 hours and classify it as an S-type asteroid according to its average colors of B — V = 0.767 ± 0.033, V — R = 0.482 ± 0.021, V — I = 0.801 ± 0.025 and the corresponding relative reflectance spectrum. These results might be indicative of differential space weathering or compositional inhomogeneity in the surface materials.

Currently two-way and three-way spacecraft Doppler tracking techniques are widely used and play important roles in control and navigation of deep space missions. Starting from a one-way Doppler model, we extend the theory to two-way and three-way Doppler models by making them include possible violations of the local Lorentz invariance (LLI) and the local position invariance (LPI) in order to test the Einstein equivalence principle, which is the cornerstone of general relativity and all other metric theories of gravity. After taking the finite speed of light into account, which is the so-called light time solution (LTS), we make these models depend on the time of reception of the signal only for practical convenience. We find that possible violations of LLI and LPI cannot affect two-way Doppler tracking under a linear approximation of LTS, although this approximation is sufficiently good for most cases in the solar system. We also show that, in three-way Doppler tracking, possible violations of LLI and LPI are only associated with two stations, which suggests that it is better to set the stations at places with significant differences in velocities and gravitational potentials to obtain a high level of sensitivity for the tests.

At present, optical autonomous navigation has become a key technology in deep space exploration programs. Recent studies focus on the problem of orbit determination using autonomous navigation, and the choice of filter is one of the main issues. To prepare for a possible exploration mission to Mars, the primary emphasis of this paper is to evaluate the capability of three filters, the extended Kalman filter (EKF), unscented Kalman filter (UKF) and weighted least-squares (WLS) algorithm, which have different initial states during the cruise phase. One initial state is assumed to have high accuracy with the support of ground tracking when autonomous navigation is operating; for the other state, errors are set to be large without this support. In addition, the method of selecting asteroids that can be used for navigation from known lists of asteroids to form a sequence is also presented in this study. The simulation results show that WLS and UKF should be the first choice for optical autonomous navigation during the cruise phase to Mars.

In January, 2008 the Chinese Small Telescope ARray (CSTAR) was successfully deployed at Dome A, Antarctica. Because CSTAR consists of four static 14.5 cm telescopes pointing at the same 4.5° × 4.5° field around the south celestial pole, diurnal motion can be seen in its field of view. The stars are centered at different positions in different exposure frames. During four months of continuous observations during the polar night of 2008, about 0.3 million i-band images were obtained. In the latest version of the released photometric catalog, the effects of diurnal motion of the stars on the static CSTAR optical system can be obviously found. In this work, we update the CSTAR catalog by carefully analyzing and correcting the systematic errors caused by diurnal motion of stars on imperfectly flat-fielded frames.

The cross section for a neutron-deuteron (nd) radiative capture is calculated using the pionless effective field theory including isospin symmetry breaking (ISB) corrections up to higher order. The triton is studied as a three-body bound state and one has to take into account various ISB effects, relativistic corrections and external electromagnetic currents. The isospin violation in nd radiative capture is improved compared to the one at NLO and N²LO. The cross section is determined to be σ_tot = [0.505 ± 0.003] mb up to N²LO. A satisfactory agreement between theory and experiment for the calculated cross section has been found by insertion of three-body forces and ISB effects.

The reduced transition probabilities from an electric quadrupole B(E₂) and reduced transition probabilities from a magnetic dipole B(M₁) between the ground state and the first excited state have been calculated for the ³He(α,γ)⁷Be, ⁸Be(α,γ)¹²C and ¹²C(α,γ)¹⁶O radiative capture reactions with the M₃Y potential. These reactions are important in stellar evolution. The calculated B(M₁) and B(E₂) for ⁷Be nuclei are found to be 1.082 × 10⁻³ e² fm² and 1.921 e² fm⁴ from transitions 3/2⁻ to 1/2⁻, respectively. The obtained values for reduced transition probabilities B(E₂) for the ¹²C and ¹⁶O nuclei from transitions 0⁺ to 2⁺ are 12.54 e² fm⁴ and 14.18 e² fm⁴, respectively. The results are in satisfactory agreement with available experimental data.