脉冲星在空间飞行器定位中的应用     

杨廷高  南仁东  金乘进  甘恒谦 《天文学进展》2007,25(3):249-261

利用脉冲星钟模型能高精度地预报脉冲星脉冲到达太阳系质心的时间。基于脉冲星时、空参考架可实现各类空间飞行器的自主导航。讨论了脉冲星钟的模型和脉冲星导航系统的框架结构,描述了脉冲星导航的基本原理和算法。指出脉冲星导航系统对脉冲星脉冲到达探测器时刻的测量精度,是决定空间飞行器位置解算精度的关键因素。脉冲星导航观测采用的原子钟如果足够稳定,则空间飞行器位置的解算方法可以简化。在脉冲星导航系统计时观测精度达到或优于几十微秒量级时,脉冲星视差、相对论效应的影响是不可忽略的。对脉冲星导航系统开发设计中的关键技术和进一步研究的主要问题进行了初步分析和讨论。  相似文献   

Synchro－Curvature　Radiation──弯曲磁场中一种新的、更普遍的辐射     

张家铝  郑广生 《天文学报》1995,(4)

Ｓｙｎｃｈｒｏ－ＣｕｒｖａｔｕｒｅＲａｄｉａｔｉｏｎ──弯曲磁场中一种新的、更普遍的辐射张家铝（中国科技大学天体物理中心合肥２３００２６）郑广生（香港大学物理系）关键词同步辐射，曲率辐射，脉冲星磁层在脉冲星的辐射模型中，同步辐射和曲率辐射占有极其重要...  相似文献   

K－P关系和射电脉冲星辐射束宽度的估计     

吴鑫基 《中国天文和天体物理学报》1995,(1)

从极冠模型出发，利用观测参数Ｋ和辐射锥角的关系，通过研究Ｋ－Ｐ关系导出了对确定辐射区参数有重要意义的辐射束宽和周期的关系。给出了一种估计辐射束宽度和磁倾角的方法。  相似文献   

Repeating fast radio bursts reveal the secret of pulsar magnetospheric activity     

Renxin Xu  Weiyang Wang 《Astronomische Nachrichten》2024,345(2-3):e230153

The puzzling mechanism of coherent radio emission remains unknown, but fortunately, repeating fast radio bursts (FRBs) provide a precious opportunity, with extremely bright subpulses created in a clear and vacuum-like pulsar magnetosphere. FRBs are millisecond-duration signals that are highly dispersed at distant galaxies but with uncertain physical origin(s). Coherent curvature radiation by bunches has already been proposed for repeating FRBs. The charged particles are created during central star's quakes, which can form bunches streaming out along curved magnetic field lines, so as to trigger FRBs. The nature of narrow-band radiation with time-frequency drifting can be a natural consequence that bunches could be observed at different times with different curvatures. Additionally, high linear-polarization can be seen if the line of sight is confined to the beam angle, whereas the emission could be highly circular-polarized if off-beam. It is also discussed that pulsar surface may be full of small hills (i.e., zits) which would help producing bulk of energetic bunches for repeating FRBs as well as for rotation-powered pulsars.  相似文献   

The micro-glitch in PSR B1821−24: a case for a strange pulsar?     

Raka Dona Ray Mandal  Sushan Konar  Mira Dey  Jishnu Dey 《Monthly notices of the Royal Astronomical Society》2009,399(2):822-826

The single glitch observed in PSR B1821−24, a millisecond pulsar in M28, is unusual on two counts. First, the magnitude of this glitch is at least an order of magnitude smaller  (Δν/ν∼ 10⁻¹¹)  than the smallest glitch observed to date. Secondly, all other glitching pulsars have strong magnetic fields with   B ≳ 10¹¹ G  and are young, whereas PSR B1821−24 is an old recycled pulsar with a field strength of  2.25 × 10⁹ G  . We have earlier suggested that some of the recycled pulsars could actually be strange quark stars. In this work, we argue that the crustal properties of such a strange pulsar are just right to give rise to a glitch of this magnitude, explaining the scarcity of larger glitches in millisecond pulsars.  相似文献   

Search for TeV gamma-rays from Geminga pulsar     

B.B. Singh  V.R. Chitnis  D. Bose  M.A. Rahman  S.S. Upadhya  K.S. Gothe  B.K. Nagesh  P.N. Purohit  Shobha K. Rao  Kamesh K. Rao  S.K. Sharma  P.V. Sudersan  B.L. Venkateshmurthy  P.R. Vishwanath  B.S. Acharya 《Astroparticle Physics》2009,32(2):120-128

We present the results of observation of the Geminga pulsar carried out in the TeV energy band during the 6 year period spanning 2000–2006 using the Pachmarhi Array of Cherenkov Telescopes (PACT). A long stretch of data, new computer codes and the “Tempo” package have been used in the present analysis. We have searched for evidence of pulsed emission of γ-rays from the Geminga pulsar using the post-glitch pulsar elements obtained by Jackson and Halpern from X-ray/γ-ray satellite data. We do not see any significant evidence for pulsed emission from the Geminga pulsar at a threshold energy of 825 GeV. In this paper we present our results on the light curve in the TeV energy band, set an upper limit on the time averaged flux of γ-rays, and compare our results with other ground based observations.  相似文献   

利用σ_z(τ)方法对脉冲星时与原子时长期稳定度对比分析     

张彩红  刘经南  聂桂根 《武汉大学学报(信息科学版)》2012,37(7):847-850

首次研究了毫秒脉冲星PSR J1939+2134共7.5a的双频计时残差序列的特征,通过分析不同行星星历对脉冲星计时精度的影响,建议使用DE421;采用σz(τ)方法估计了脉冲星时与原子时的稳定度,发现脉冲星时的稳定度一直处于上升趋势,6a高于10-15。由此可见,脉冲星时作为守时和授时的时间标准具有优势。  相似文献   

Influence of Neutron Star Parameters on Evolutions of Different Types of Pulsar     

Oktay?H.?GuseinovEmail author  A?kin?Ankay  Sevin??O.?Tagieva 《Astrophysics and Space Science》2005,298(4):553-558

Influences of the mass, moment of inertia, rotation, absence of stability in the atmosphere and some other parameters of neutron stars on the evolution of pulsars are examined. It is shown that the locations and evolutions of soft gamma repeaters, anomalous X-ray pulsars and other types of pulsar on the period versus period derivative diagram can be explained adopting values of B < 10¹⁴ G for these objects if they have smaller mass (e.g. about 0.5 Solar mass) compared to the conventionally adopted values of mass. This approach gives the possibility to explain many properties of different types of pulsar.  相似文献   

利用γ射线数据测量Geminga脉冲星的自行     

程凌翔  孙学军  李惕碚 《中国天文和天体物理学报》1995,(3)

通过比较不同观测中Ｇｅｍｉｎｇａ脉冲星的γ射线绝对位相，测量出了不同时间Ｇｅｍｉｎｇａ的位置。这些位置表明Ｇｅｍｉｎｇａ自行的赤经分量为０．２２６±０．０３弧秒／年，与它的一个最可能的光学对应体Ｇ″的自行相一致，从而独立地确定了Ｇ″与Ｇｅｍｉｎｇａ之间的对应关系。  相似文献   

Very high energy gamma rays from the crab pulsar     

P. R. Vishwanath 《Journal of Astrophysics and Astronomy》1987,8(1):69-78

The Ooty data on VHE (> 600 GeV) γ-rays from the Crab pulsar have been used to look at possible emission on three different timescales,viz. years, minutes and hours. When averaged over three years of observation, there is no significant time-averaged emission. But interesting aspects are revealed when the data are subdivided into miniruns of one-minute duration. Minutes with moderate γ-ray activity were isolated with a κ² analysis. The summed phasogram of such minutes shows two strong peaks coinciding with the radio main pulse and the interpulse respectively. The probability that these are due to chance is small. The phasogram has a bimodal distribution which indicates some emission from the middle region between the two phases. In general, there is no significant emission on the timescale of a few hours. However, the main pulse, as well as the bimodal distribution, were seen also in the total data of two nights of simultaneous observation at two sites during 1984–1985.  相似文献