Magnetohydrodynamic stellar and disk winds: Application to planetary nebulae

被引:102
作者
Blackman, EG
Frank, A
Welch, C
机构
[1] Univ Rochester, Dept Phys & Astron, Rochester, NY 14627 USA
[2] Univ Calif Santa Barbara, ITP, Santa Barbara, CA 93106 USA
关键词
accretion; accretion disks; ISM : jets and outflows; ISM : magnetic fields; MHD; planetary nebulae : general; stars : AGB and post-AGB;
D O I
10.1086/318253
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
MHD winds can emanate from both stars and surrounding disks. When the two systems are coupled by accretion, it is of interest to know how much wind power is available and which (if either) of the two rotators dominates that power. We investigate this in the context of multipolar planetary nebulae (PNs) and protoplanetary nebulae (PPNs), for which recent observations have revealed the need for a wind power source in excess of that available from radiation driving and a possible need for magnetic shaping. We calculate the MHD wind power from a coupled disk and star, where the former results from binary disruption. The resulting wind powers depend only on the accretion rate and stellar properties. We find that if the stellar envelope were initially slowly rotating, the disk wind would dominate throughout the evolution. If the envelope of the star were rapidly rotating, the stellar wind could initially be of comparable power to the disk wind until the stellar wind carries away the star's angular momentum. Since an initially rapidly rotating star can have its spin and magnetic axes misaligned to the disk, multipolar out-flows can result from this disk wind system. For times greater than a spin-down time, the post-asymptotic giant branch stellar wind is slaved to the disk for both slow and rapid initial spin cases, and the disk wind luminosity dominates. We find a reasonably large parameter space where a hybrid star+disk MHD-driven wind is plausible and where both or either can account for PPN and PN powers. We also speculate on the morphologies which may emerge from the coupled system. The coupled winds might help explain the shapes of a number of remarkable multishell or multipolar nebulae. Magnetic activity such as X-ray flares may be associated with both the central star and the disk and would be a valuable diagnostic for the dynamical role of MHD processes in PNs.
引用
收藏
页码:288 / 298
页数:11
相关论文
共 71 条
[1]  
Alcolea J, 2000, ASTR SOC P, V199, P347
[2]   Magnetic braking of T Tauri stars [J].
Armitage, PJ ;
Clarke, CJ .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1996, 280 (02) :458-468
[3]   Instability, turbulence, and enhanced transport in accretion disks [J].
Balbus, SA ;
Hawley, JF .
REVIEWS OF MODERN PHYSICS, 1998, 70 (01) :1-53
[4]   A POWERFUL LOCAL SHEAR INSTABILITY IN WEAKLY MAGNETIZED DISKS .1. LINEAR-ANALYSIS [J].
BALBUS, SA ;
HAWLEY, JF .
ASTROPHYSICAL JOURNAL, 1991, 376 (01) :214-222
[5]   Fliers and other microstructures in planetary nebulae. IV. Images of elliptical PNs from the Hubble Space Telescope [J].
Balick, B ;
Alexander, J ;
Hajian, AR ;
Terzian, Y ;
Perinotto, M ;
Patriarchi, P .
ASTRONOMICAL JOURNAL, 1998, 116 (01) :360-371
[7]  
Balick B, 2000, ASTR SOC P, V199, P41
[8]   Relativistic precessing jets and cosmological gamma-ray bursts [J].
Blackman, EG ;
Yi, I ;
Field, GB .
ASTROPHYSICAL JOURNAL, 1996, 473 (02) :L79-L82
[9]   Mean magnetic field generation in sheared rotators [J].
Blackman, EG .
ASTROPHYSICAL JOURNAL, 2000, 529 (01) :138-145
[10]  
BLACKMAN EG, 2000, IN PRESS NATURE