发现一颗大质量恒星的 X 射线脉冲。

Discovery of X-ray pulsations from a massive star.

机构信息

Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany.

FNRS, GAPHE, Department A.G.O., University of Liège, 4000 Liège, Belgium.

出版信息

Nat Commun. 2014 Jun 3;5:4024. doi: 10.1038/ncomms5024.

DOI:10.1038/ncomms5024

PMID:24892504

Abstract

X-ray emission from stars much more massive than the Sun was discovered only 35 years ago. Such stars drive fast stellar winds where shocks can develop, and it is commonly assumed that the X-rays emerge from the shock-heated plasma. Many massive stars additionally pulsate. However, hitherto it was neither theoretically predicted nor observed that these pulsations would affect their X-ray emission. All X-ray pulsars known so far are associated with degenerate objects, either neutron stars or white dwarfs. Here we report the discovery of pulsating X-rays from a non-degenerate object, the massive B-type star ξ(1) CMa. This star is a variable of β Cep-type and has a strong magnetic field. Our observations with the X-ray Multi-Mirror (XMM-Newton) telescope reveal X-ray pulsations with the same period as the fundamental stellar oscillations. This discovery challenges our understanding of stellar winds from massive stars, their X-ray emission and their magnetism.

摘要

X 射线发射的恒星比太阳大很多，这一发现是在 35 年前才首次提出的。这样的恒星会产生快速的恒星风，在恒星风中可能会产生激波，而人们普遍认为 X 射线是从激波加热的等离子体中发射出来的。许多大质量恒星还会脉动。然而，迄今为止，人们既没有从理论上预测到，也没有观察到这些脉动会影响它们的 X 射线发射。迄今为止，所有已知的 X 射线脉冲星都与简并物体（中子星或白矮星）有关。在这里，我们报告了从非简并物体、大质量 B 型星 ξ(1) CMa 中探测到脉冲 X 射线的发现。这颗恒星是β Cep 型变星，具有很强的磁场。我们利用 X 射线多镜望远镜（XMM-Newton）进行的观测揭示了与恒星基本振动具有相同周期的 X 射线脉冲。这一发现挑战了我们对大质量恒星的恒星风、它们的 X 射线发射和它们的磁场的理解。