Can the Rapid Braking of the White Dwarf in AE Aquarii Be Explained in Terms of the Gravitational-Wave Emitter Mechanism?
The spin-down power of the white dwarf in the close binary AE Aquarii significantly exceeds the bolometric luminosity of the system. The interpretation of this phenomenon in terms of the gravitational-wave emitter mechanism has been recently suggested by Choi & Yi. The basic assumption of their interpretation is that the spatially limited blobs or mounds of mass δm ~ 10-3 M☉ are present at the magnetic poles of the white dwarf. We show that the mounds of this mass can be confined by the magnetic field of the white dwarf only if the dipole magnetic moment of the star exceeds 4 × 1037 G cm3. Under these conditions, however, the magnetodipole losses of the white dwarf would exceed the evaluated spin-down power by 6 orders of magnitude. On this basis, we discard the possibility that the observed rapid braking of the white dwarf in AE Aqr can be explained in terms of the mechanism proposed by Choi & Yi.
On the mass transfer in AE Aquarii
The observed properties of the close binary AE Aqr indicate that the mass transfer in this system operates via the Roche lobe overflow mechanism, but the material transferred from the normal companion is neither accreted onto the surface of the white dwarf nor stored in a disk around its magnetosphere. As previously shown, such a situation can be realized if the white dwarf operates as a propeller. At the same time, the efficiency of the propeller action by the white dwarf is insufficient to explain the rapid braking of the white dwarf, which implies that the spin-down power is in excess of the bolometric luminosity of the system. To avoid this problem we have simulated the mass-transfer process in AE Aqr assuming that the observed braking of the white dwarf is governed by a pulsar-like spin-down mechanism. We show that the expected H α  Doppler tomogram in this case resembles the tomogram observed from the system. We find that the agreement between the simulated and the observed tomograms is rather good provided the mean value of the mass-transfer rate $\langle\dot{M}\rangle$ ~ 5 $\times$ $10^{16}~{\rm g~s^{-1}}$. Three spatially separated sources of H α  emission can be distinguished within this approach. The structure of the tomogram depends on the relative contributions of these sources to the H α  emission and is expected to vary from night to night.
Numerical Simulation of Thermal Sensitivity for Explosives
In order to compare the thermal sensitivity of several typical explosives, this article solved numerically one-dimensional transient heat conduction equation including thermal decomposition for explosives with finite difference method. The explicit difference equations under different boundary conditions were established, and the corresponding stability criterion was derived. The ignition times for typical explosives were calculated, which was used to evaluate thermal sensitivity of explosives.