Self-consistent neutrino and UHE cosmic ray spectra from Mrk 421     

《Astroparticle Physics》2014

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On the structure of thin magnetized accretion disks of active galactic nuclei and their coronal radiation     

Yang Lan-tian  Wu Xue-bin  Yang Pi-bo 《Chinese Astronomy and Astrophysics》1991,15(4):386-396

By taking magnetic stress in place of viscosity as the mechanism for angular moaentum transfer, the effect of frozen magnetic field on the structure of a geometrically thin accretion disk is examined. It is shown that the disk is quasi-Keplerian and its total luminosity is twice the luminosity in the standard disk model. In the inner region, there exists a narrow cool region and the highly collimated jet is formed under the action of the azimuthal component of the magnetic field. Also, we discuss the possibility that a magnetized corona be formed near the surface of the accretion disk and a wide band radiation issuing therefrom. The model suggested here can easily and reasonably explain the major AGN properties such as the radiation variation, the “bumps” in the optical, ultraviolet and soft X-ray ranges, etc.  相似文献   

银河核球X射线源GX9＋1的振荡现象     

余文飞  季惕碚  程凌翔  孙学军  吴枚 《中国天文和天体物理学报》1994,(3)

分析１９８５年ＥＸＯＳＡＴ卫星对银河核球Ｘ射线源ＧＸ９＋１的观测数据，发现该源存在几百秒量级的振荡现象，这一结果有助于了解小质量Ｘ射线双星Ｇｘ９＋１的吸积特性和轨道运动。  相似文献   

振动Kuzmin盘中恒星的运动性质     

傅燕宁  孙义燧 《天文学报》1997,38(2):119-128

本文研究振动盘中恒星的运动性质．所采用的势模型为它由一种具简单径向振动模态的Kuzmin盘和一种对数晕共同产生．得到的主要结论是：（1）恒星存在稳定且有序的近圆轨道；（2）盘振动对角动量较小的恒星及远离近圆轨道的恒星影响较大；（3）盘中大部分恒星的运动是有序的；（4）远离近圆轨道的恒星一般作混沌运动，并且最终可能逃逸，但在一个Hubble时间内实际逃逸的恒星比例较小；（5）盘振动可能是振动Kurmin盘中某些星团形成并长期维持的机制之一，盘振动幅度越大，盘中星团数目可能越多；在同一个星系盘中，角动量越大的星团数目可能越少．  相似文献   

沿切向点轨迹CO和HⅠ的发射度与旋臂段的比较     

向德琳 《中国天文和天体物理学报》1990,(3)

为了在研究银河系结构时摆脱由运动学不确定性带来的困难,本文导出了沿银道面切向点轨迹HⅠ和CO发射度的径向和银经分布。所用的谱线资料范围是10°相似文献   

Magnetic fields in the Galaxy     

Richard Wielebinski 《地球物理与天体物理流体动力学》2013,107(1-3):19-22

Abstract

Methods of measuring magnetic field strengths in astrophysics are reviewed. These determine that a magnetic field of 2–3μG lies approximately along the local spiral arm of the Galaxy. Faraday rotation measures indicate that abrupt field reversals occur in a number of directions. At the centre of the Galaxy, the field is vertical, i.e. perpendicular to the plane of the Galaxy.  相似文献   

Rings of radio continuum,Co, Hα and magnetic fields in galaxies     

Richard Wielebinski 《地球物理与天体物理流体动力学》2013,107(1-3):49-51

Abstract

Observations are reviewed that indicate the existence of rotating rings in a number of galaxies that possess poloidal magnetic fields in their nuclear regions, including our own Galaxy. Jets from these, possibly aligned with the poloidal field, may also be present. The role of these rings in dynamo processes is briefly discussed.  相似文献   

The Meteors, Meteoroids and Interplanetary Dust Program of the International Heliophysical Year 2007/9     

Svitlana V. Kolomiyets  Mykola I. Slipchenko 《Earth, Moon, and Planets》2008,102(1-4):305-307

Under the title ‘Meteors, Meteoroids and Interplanetary Dust’, meteor research is included in the program of the International Heliophysical Year 2007/9.We list issues for coordinated meteor research within the framework of this global international program.  相似文献   

春节人口迁移的气候效应:以郑州为例   总被引：1，自引：1，他引：0  

吴凌云  张井勇  远芳 《气候与环境研究》2016,21(1):41-46

目前,我们对人类活动通过温室气体、气溶胶和土地利用对气候产生重要影响已经获得了很多认识。但是,人口迁移流动在多大程度上能够影响气候尚不清楚。中国春节期间的人口大迁移是世界上每年最大规模的人类迁徙。利用城市站和参考站的气温差表示城市热岛强度,以一个典型中国中部大城市—郑州为例,研究了春节人口大迁移对城市热岛效应的影响。结果表明,2005~2013年平均的春节周日平均、日最高和日最低温度郑州站与中牟站的差分别为0.16°C、0.29°C和-0.03°C,比春节周前2~4周和春节周后2~4周的平均值低了0.50°C、0.06°C和0.66°C。相对变化而言,日平均、日最高和日最低温度的差分别降低了76%、16%和105%。春节周日平均和日最低温度的差的变化都通过了99%的信度检验。  相似文献   

The line-of-sight velocities of OB associations and molecular clouds in a wide solar neighborhood: The streaming motions of stars and gas in the Perseus arm     

T. G. Sitnik 《Astronomy Letters》2003,29(5):311-320

We compare the line-of-sight velocities of stars in OB associations within 3 kpc of the Sun and the molecular clouds closest to them. The Perseus arm is used as an example to show that the line-of-sight velocity ranges in which OB-association stars, molecular clouds, and H II regions ionized by these association stars are observed overlap. The streaming motions produced by density waves in the (l, V_LSR) plane were found to lead to an inversion of the distances to objects of the Perseus arm and the interarm space beyond this arm.  相似文献