THE UNUSUAL X-RAY PULSE TIMING OF AE AQUARII

被引:22
作者
DEJAGER, OC
机构
[1] Lab. for High Energy Astrophysics, NASA, Goddard Space Flight Center, Greenbelt
[2] Department of Physics, PU for CHE
关键词
STARS; BINARIES; INDIVIDUAL (AE AQUARII); X-RAYS;
D O I
10.1086/170428
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The novalike variable AE Aquarii exhibits emission and absorption lines of which the radial velocities are antiphased by 180-degrees and both describe a circular orbit with a period of 9.88 hr. There is therefore good reason to believe that the emission-line orbit describes the true orbit of the white dwarf. The system also emits coherent pulsed optical light with a period of 33.s0767 and the corresponding timing delays describe a distorted orbit which is shifted by 60-degrees relative to the emission-line orbit. The semiamplitude of the pulse-timing orbit is also a factor (0.865 +/- 0.077) smaller than that of the emission-line orbit. The pulsed optical light may then be due to the reprocessing of the EUV/X-rays emitted from the white dwarf (with a rotation period of 33.s0460) incident on a target fixed in the orbital frame of the binary (Robinson, Shafter, & Balachandran), to give optical pulsations at an orbital beat period. From a reanalysis of the Einstein X-ray data on AE Aqr we show the following: (1) The most significant X-ray period is indeed the optical period and (2) at this period, the X-ray pulse-timing orbit follows the same orbit as the optical pulse-timing orbit. (3) The direct X-ray beam from the white dwarf is at least 4 times weaker than the pulsed X-ray signal at the optical period. (4) Given the above mentioned correlations with the optical, we infer that the X-ray pulsations must be originating at the same target in the orbit responsible for the optical pulsations. (5) There is a possible orbital modulation of the pulsed X-ray signal with a minimum in the almost-equal-to 60-degrees phase interval between superior conjunction of the optical pulse-timing and emission-line orbits. (6) We also show that the X-ray pulse has slipped at least twice in phase by more than 30% in 2 years' time. It remains then to be shown how the direct X-ray pulse from the white dwarf can be so weak given the optically thin disk which is viewed at an elevation angle > 30-degrees above the disk.
引用
收藏
页码:286 / 292
页数:7
相关论文
共 27 条