arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0905.4829astro-ph.HE
收藏

在吸积的磁性白矮星中是否有磁场重组或衰变的证据?

Is there evidence for field restructuring or decay in accreting magnetic white dwarfs?

C. M. Zhang, D. T. Wickramasinghe, L. Ferrario

摘要:

在简化的假设下,研究了吸积非球形磁白矮星表面初始偶极场的磁场演化。在极区的吸积倾向于将磁场向恒星赤道平流,然后将其掩埋。欧姆扩散和磁流体动力学不稳定性抵消了这种趋势。有人认为,如果物质的吸积率为$\dot{M}_{\rm crit} \sim 10^{16}$ g s $^{-1}$和总质量吸积超过一个临界值$ΔM_{\rm crit} \sim 0.1-0.2\ms$,该领域可能会被重组,并减少极场达到最小值$\sim 10^3$ G(“底场”)独立于初始场强。低于这个临界吸积率,场的扩散速度比平流速度快,吸积对场的强度和结构几乎没有影响。

英文摘要:

The evolution of the magnetic field of an accreting magnetic white dwarf with an initially dipolar field at the surface has been studied for non-spherical accretion under simplifying assumptions. Accretion on to the polar regions tends to advect the field toward the stellar equator which is then buried. This tendency is countered by Ohmic diffusion and magneto-hydrodynamic instabilities. It is argued that if matter is accreted at a rate of $\dot{M}_{\rm crit} \sim 10^{16}$ g s$^{-1}$ and the total mass accreted exceeds a critical value $ΔM_{\rm crit} \sim 0.1-0.2\ms$, the field may be expected to be restructured, and the polar field to be reduced} reaching a minimum value of $\sim 10^3$ G (the "bottom field") independently of the initial field strength. Below this critical accretion rate, the field diffuses faster than it can be advected, and accretion has little effect on field strength and structure.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑