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Hyperpolarized Xenon for NMR and MRI Applications
Published on: September 6, 2012
来自磁星的短暂脉冲无线电辐射
Fernando Camilo1, Scott M Ransom, Jules P Halpern
1Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, New York 10027, USA. fernando@astro.columbia.edu
Nature
|August 25, 2006
概括
异常X射线脉冲星 (AXP) 或磁星已经被证明可以发射无线电脉冲,这是这些天体的首次. 这一发现将磁星与普通脉冲星联系起来,并为研究它们的磁场和冠状云开辟了新的途径.
科学领域:
- * 天文学和天体物理学
- * 高能天体物理学
- * 中子星物理学
背景情况:
- *异常X射线脉冲星 (AXP) 是具有超强磁场 (>10^14 G) 的中子星,称为磁星.
- *磁星表现出明亮的,可变的X射线发射,但从未观察到发射无线电脉冲,与普通脉冲星不同.
- *XTE J1810-197,一个AXP,在2003年显示出显著的X射线爆发,随后检测到无线电源.
研究的目的:
- * 为了研究异常X射线脉冲星XTE J1810-197.7的无线电发射特性.
- * 为了确定磁星是否可以表现出无线电脉冲星行为.
- *将磁星观测与普通无线电脉冲星的观测联系起来.
主要方法:
- *使用射电望远镜观测XTE J1810-197的无线电脉冲.
- *分析检测到的无线电脉冲的特征,包括偏振和流量.
- *将无线电发射特性与平常脉冲星和磁星在静止状态中的特性进行比较.
主要成果:
- * 检测到XTE J1810-197在每次旋转时都会发出明亮,狭窄和高度线性偏振的无线电脉冲.
- * 在2003年X-ray爆发之前,没有观察到XTE J1810-197的无线电辐射.
- * XTE J1810-197的无线电流量每天都在变化,并且在无线电频率上几乎是恒定的,成为已知的20 GHz以上最亮的中子星.
结论:
- *磁星确实可以作为无线电脉冲星,弥合磁星和普通无线电脉冲星之间的差距.
- *这些发现排除了AXP的其他基于积累的模型.
- * 这些观测为磁星的磁层冠状提供了至关重要的见解.
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