On the mass transfer in AE Aquarii

Abstract

Abstract. 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 Hα 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 Ṁ ∼ 5 × 10 16 g s −1 . Three spatially separated sources of Hα emission can be distinguished within this approach. The structure of the tomogram depends on the relative contributions of these sources to the Hα emission and is expected to vary from night to night.

High-energy emission of fast rotating white dwarfs

“…Here R 8.8 is the radius of the white dwarf expressed in units of 10 8.8 cm. As recently shown by Ikhsanov et al (2004), the above mentioned estimates contradict none of the currently observed properties of the system, and the Doppler Hα tomogram simulated within this approach is in a very good agreement with the tomogram derived from spectroscopic observations of AE Aqr. On this basis estimates (3) and (4) will be used in our analysis.…”

“…The appearance of the system significantly differs from that of magnetic cataclysmic variables whose radiation is powered by the accretion process (Warner 1995). Instead, AE Aqr ejects material in the form of a non-relativistic stream (Welsh et al 1998;Ikhsanov et al 2004), and relativistic particles responsible for the radio and, possibly, high-energy emission of the system (de Jager 1994).…”

“…As recently shown by Ikhsanov et al (2004), the closest approach of the stream to the surface of the white dwarf within the EWD-model is limited to …”

On the origin of the peculiar cataclysmic variable AEAquarii

“…These peculiar properties can be explained in terms of the pulsar-like white dwarf scenario provided the surface magnetic field of the white dwarf is in excess of 50 MG (Ikhsanov, 1998;Ikhsanov et al, 2004). But how such a white dwarf was formed?…”

Flow Structure in Magnetic CVs

“…However, since the problem is very complicated, the investigations have been performed either in the frame of simplified models (King 1993;Wynn & King 1995;Wynn et al 1997;King & Wynn 1999;Norton et al 2004;Ikhsanov et al 2004;Norton et al 2008), or in a limited region of the stellar magnetosphere (Koldoba et al 2002;Romanova et al 2003Romanova et al , 2004aRomanova et al , 2004b. Only over the last few years, the authors have managed to develop a comprehensive 3D numerical model to calculate the flow structure in close binaries (Zhilkin & Bisikalo 2009, 2010a, 2010b, 2010c.…”