Indirect imaging of the accretion stream in eclipsing polars - II. HU Aquarii

被引:27
作者
Harrop-Allin, MK
Cropper, M
Hakala, PJ
Hellier, C
Ramseyer, T
机构
[1] UCL, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England
[2] Univ Helsinki, Observ & Astrophys Lab, FIN-00014 Helsinki, Finland
[3] Univ Keele, Dept Phys, Keele ST5 5BG, Staffs, England
[4] Univ Cent Arkansas, Dept Phys & Astron, Conway, AR 72032 USA
关键词
accretion; accretion discs; binaries : eclipsing; stars : individual : HU Aqr; stars : magnetic fields; novae; cataclysmic variables;
D O I
10.1046/j.1365-8711.1999.02780.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We apply our technique for indirect imaging of the accretion stream to the polar HU Aquarii, using eclipse profiles observed when the system was in a high accretion state. The accretion stream is relatively luminous, contributing as much as the accretion region on the white dwarf, or more, to the overall system brightness. We model the eclipse profiles using a model stream consisting of a ballistic trajectory from the L1 point followed by a magnetically channelled trajectory that follows a dipole field line out of the orbital plane. We perform model fits using two geometries: a stream that accretes on to both footpoints of the field line, and a stream that accretes only on to the footpoint of the field line above the orbital plane. The stream images indicate that the distribution of emission along the stream is not a simple function of the radial distance from the white dwarf. The stream is redirected by the magnetic field of the white dwarf at a distance 1.0-1.3 x 10(10) cm from the white dwarf; this implies a mass transfer rate in the range 8-76 x 10(16) g s(-1). The absorption dips in the light curve indicate that the magnetically entrained part of the stream moves from 42 degrees to 48 degrees from the line of centres over the three nights of observation. This is in close agreement with the results of the one-footpoint models, suggesting that this is the more appropriate geometry for these data. The stream images show that, in almost all sections of the stream, the flux peaks in B and is successively fainter in U, V and R.
引用
收藏
页码:807 / 817
页数:11
相关论文
共 33 条
[1]  
Allen C. W., 1973, Astrophysical Quantities
[2]  
Bailey J, 1995, ASTR SOC P, V85, P10
[3]   THE ECLIPSE LIGHT CURVES OF UZ FOR [J].
BAILEY, J ;
CROPPER, M .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1991, 253 (01) :27-34
[4]  
BARWIG H, 1994, ASTRON ASTROPHYS, V288, P204
[6]  
DIAZ MP, 1994, ASTRON ASTROPHYS, V283, P508
[7]  
FAULKNER J, 1971, APJ, V170, pL199
[8]   A BROAD OBSERVATIONAL STUDY OF THE ECLIPSING MAGNETIC CATACLYSMIC VARIABLE RE-2107-05 [J].
GLENN, J ;
HOWELL, SB ;
SCHMIDT, GD ;
LIEBERT, J ;
GRAUER, AD ;
WAGNER, RM .
ASTROPHYSICAL JOURNAL, 1994, 424 (02) :967-975
[9]   THE DISCOVERY OF A NEW BRIGHT ECLIPSING AM-HER SYSTEM [J].
HAKALA, PJ ;
WATSON, MG ;
VILHU, O ;
HASSALL, BJM ;
KELLETT, BJ ;
MASON, KO ;
PIIROLA, V .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1993, 263 (01) :61-68
[10]  
HAKALA PJ, 1995, ASTRON ASTROPHYS, V296, P164