The hydromagnetic structure of a neutron star accreting symmetrically at both magnetic poles is calculated as a function of accreted mass, M a, starting from a polytropic sphere plus central magnetic dipole (M a =0) and evolving the configuration through a quasistatic sequence of twodimensional, Grada€“Shafranov equilibria as M a increases. It is found that the accreted material spreads equatorward under its own weight, compressing the magnetic field into a thin boundary layer and burying it everywhere except in a narrow, equatorial belt. The magnetic dipole moment of the star is given by ?μ=5.2?—1024(B 0/1012.5G)1.3(M a/10a?’8 M ê? yra?’1)0.18(M a/Mê?)a?’1.3Gcm3, and the fractional difference between its principal moments of inertia is given by D?=2.1?—10a?’5(B 0/1012.5G)0.27(M a/10a?’8 Myra?’1)0.18(M a/M ê?)1.7, for M a in the range 10a?’5 M a/Mê?10a?’1,where B 0 is the pre-accretion magnetic field strength, and M a is the accretion rate.
展开▼
机译：计算一个在两个磁极上对称吸积的中子星的水磁结构，作为吸积质量M a的函数，该质量从多变球体加上中心磁偶极子（M a = 0）开始，并通过二维准静态序列演化，Grada-Shafranov平衡随着M a的增加而增加。发现积聚的物质在自重作用下向赤道扩散，将磁场压缩成薄的边界层，并将其掩埋在除赤道狭窄的窄带之外的所有地方。恒星的磁偶极矩由？μ= 5.2？-1024（B 0 / 1012.5G）1.3（M a / 10a？'8 Mê？yra？'1）0.18（M a /Mê？）a给出Δ′1.3Gcm 3，其主转动惯量之间的分数差由下式给出：D′＝ 2.1°—10a′′5（B 0 / 1012.5G）0.27（M a / 10a′′8 Myra′′′1）0.18 （M a / Mê）1.7，对于M a在10a？'5 M a /Mê？10a？'1范围内，其中B 0是预积磁场强度，而M a是积聚率。
展开▼
