Jeremy Heyl, Victor Doroshenko, Denis González-Caniulef, Ilaria Caiazzo, Juri Poutanen, Alexander Mushtukov, Sergey S. Tsygankov, Demet Kirmizibayrak, Matteo Bachetti, George G. Pavlov, Sofia V. Forsblom, Christian Malacaria, Valery F. Suleimanov, Iván Agudo, Lucio Angelo Antonelli, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Alessandro Di Marco, Immacolata Donnarumma, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Wataru Iwakiri, Svetlana G. Jorstad, Philip Kaaret, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, Michela Negro, C.-Y. Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, Abel Lawrence Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, Fei Xie, Silvia Zane
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引用次数: 0
Abstract
In an accreting X-ray pulsar, a neutron star accretes matter from a companion star through an accretion disk. The magnetic field of the rotating neutron star disrupts the inner edge of the disk, funnelling the gas to flow onto the poles on its surface. Hercules X-1 is a prototypical persistent X-ray pulsar about 7 kpc from Earth. Its emission varies on three distinct timescales: the neutron star rotates every 1.2 s, it is eclipsed by its companion each 1.7 d, and the system exhibits a superorbital period of 35 d, which has remained stable since its discovery. Several lines of evidence point to the source of this variation as the precession of the accretion disk or that of the neutron star. Despite the many hints over the past 50 yr, the precession of the neutron star itself has yet not been confirmed or refuted. X-ray polarization measurements (probing the spin geometry of Her X-1) with the Imaging X-ray Polarimetry Explorer suggest that free precession of the neutron star crust sets the 35 d period; this has the important implication that its crust is somewhat asymmetric by a few parts per ten million. IXPE has revealed how the spin of the accreting neutron star Hercules X-1 changes in three dimensions. The spin axis of the star moves both through the star and across the sky, hinting that the crust of the star is asymmetric by almost one part in a million.
在吸积 X 射线脉冲星中，一颗中子星通过吸积盘吸积来自伴星的物质。旋转的中子星的磁场破坏了吸积盘的内缘，使气体流向吸积盘表面的两极。海格力斯 X-1 是一颗典型的持续 X 射线脉冲星，距离地球约 7 kpc。它的发射在三个不同的时间尺度上变化：中子星每 1.2 秒旋转一次，它每 1.7 天被其伴星食一次，该系统显示出 35 天的超轨道周期，自发现以来一直保持稳定。一些证据表明，这种变化的来源是吸积盘或中子星的前向运动。尽管在过去的 50 年中出现了许多暗示，但中子星本身的前摄动尚未得到证实或反驳。利用成像 X 射线偏振探测仪进行的 X 射线偏振测量（探测 Her X-1 的自旋几何）表明，中子星外壳的自由前冲设定了 35 d 周期；这具有重要的含义，即其外壳在某种程度上是不对称的，为千万分之几。
Nature AstronomyPhysics and Astronomy-Astronomy and Astrophysics
CiteScore
19.50
自引率
2.80%
发文量
252
期刊介绍：
Nature Astronomy, the oldest science, has played a significant role in the history of Nature. Throughout the years, pioneering discoveries such as the first quasar, exoplanet, and understanding of spiral nebulae have been reported in the journal. With the introduction of Nature Astronomy, the field now receives expanded coverage, welcoming research in astronomy, astrophysics, and planetary science. The primary objective is to encourage closer collaboration among researchers in these related areas.
Similar to other journals under the Nature brand, Nature Astronomy boasts a devoted team of professional editors, ensuring fairness and rigorous peer-review processes. The journal maintains high standards in copy-editing and production, ensuring timely publication and editorial independence.
In addition to original research, Nature Astronomy publishes a wide range of content, including Comments, Reviews, News and Views, Features, and Correspondence. This diverse collection covers various disciplines within astronomy and includes contributions from a diverse range of voices.
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