| An Estimation of the Initial Period of Pulsars |
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| 作者姓名： | Zhan-Kui Huang and Xin-Ji Wu |
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| 作者单位： | Zhan-Kui Huang and Xin-Ji Wu
1 Department of Astronomy，Peking University，Beijing 100871
2 Chinese Academy of Sciences-Peking University Joint Beijing Astrophysics Center，Beijing 100871
3 National Astronomical Observatories，Urumqi Astronomical Observatory，Chinese Academic of Science，Urumqi 830011 |
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| 基金项目： | Supported by the National Natural Science Foundation of China. |
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| 摘 要： | The initial period of a pulsar is an important factor in our understanding of the formation of neutron stars and of the nature of the equation of state of neutron star matter.Up to now this quantity can only be obtained for a few pulsars for which accurate age and braking index are known.Based on the theory of the offcenter dipole emission,in which pulsars obtain theiry high velocities depending on the initial periods,we calculate the initial period using the proper motion data,Because the orbital velocity of the progenitor and asymmetric kick in the supernova explosion may also contribute to the observed velocity of the pusar,the derived values of initial periods are lower limits.For normal pulsars,the initial periods are in the range of 0.6～2.6ms.For the millisecond pulsars,the initial periods are comparable to their current periods,and the ratio between the initial period and the current period increases with the decrease of the current period.For PSR B1937 21 with the shortest period of 1.56ms,the ratio is 0.77.
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| 关 键 词： | 脉冲星 中子星 初始期 轨道速度 天体观测 |
An Estimation of the Initial Period of Pulsars |
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| Zhan-Kui Huang and Xin-Ji Wu,.An Estimation of the Initial Period of Pulsars[J].Chinese Journal of Astronomy and Astrophysics,2003,3(2):166-174. |
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| Authors: | Zhan-Kui Huang Xin-Ji Wu |
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| Institution: | [1]DepartmentofAstronomy,PekingUniversity,Beijing100871, [2]ChineseAcademyofSciences-PekingUniversityJointBeijingAstrophysicsCenter,Beijing100871;NationalAstronomicalObservatories,UromqiAs |
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| Abstract: | The initial period of a pulsar is an important factor in our understanding of the formation of neutron stars and of the nature of the equation of state of neutron star matter. Up to now this quantity can only be obtained for a few pulsars for which accurate age and braking index are known. Based on the theory of the off-center dipole emission, in which pulsars obtain their high velocities depending on the initial periods, we calculate the initial period using the proper motion data. Because the orbital velocity of the progenitor and asymmetric kick in the supernova explosion may also contribute to the observed velocity of the pulsar, the derived values of initial periods are lower limits. For normal pulsars, the initial periods are in the range of 0.6 - 2.6ms. For the millisecond pulsars, the initial periods are comparable to their current periods, and the ratio between the initial period and the current period increases with the decrease of the current period. For PSR B1937+21 with the shortest period of 1.56ms, the ratio is 0.77. |
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| Keywords: | pulsaxs - stars: neutron |
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