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BL Lac天体近代观测和理论研究的某些进展 总被引:1,自引:0,他引:1
本文评述了BL Lac天体近代观测和理论研究的某些新进展。第一节为引言;第二节分析了近几年来BL Lac天体在观测方面的某些新进展;第三节综述了BL Lac天体的某些理论与模型,着重讨论了吸积与喷流模型及利用光变时标对这两种模型的判别方法;最后一节讨论了BL Lac天体的宇宙学含义。 相似文献
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讨论有关天体测量中的测光问题,介绍一些地面天体测量仪器和空间天体测量望远镜的测光研究。给出一种测光资料的处理方法,并建议利用DCMT开展天文光课题研究。 相似文献
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Bo Zhang Xing-Wu Zheng Jin-Ling Li Ye Xu 《天体物理学报》2008,8(1):127-132
The dominant source of error in VLBI phase-referencing is the troposphere at observing frequencies above 5 GHz. We compare the tropospheric zenith delays derived from VLBI and GPS data at VLBA stations collocated with GPS antennas. The systematic biases and standard deviations both are at the level of sub-centimeter. Based on this agreement, we suggest a new method of tropospheric correction in phase-referencing using combined VLBI and GPS data. 相似文献
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本文主要论述二十世纪末二十一世纪初空间天体测量新计划、新技术、以及高精度天体测量在天体物理中的应用。 相似文献
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2010~2011年度第六期国际小行星搜寻活动于2010年12月13日~2011年1月22日举行,第七期活动于2011年4月5日~2011年5月22日举行。两期活动先后有十八个学校的一百多位学生参加,取得了丰硕的成果:发现主带小行星7个,证认近地天体4个,进行近地天体观测100多次。 相似文献
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本文研究了Blazar天体的辐射性质,提出一种新的喷流模型,即具有幂律分布的极端相对论电子团从中心核注入喷流等离子体中,它在一定的注入速度下,不仅能在喷流等离子体中激发等离子体湍动,产生电磁波的相干辐射,而且能产生强的同步辐射。利用等离子体的弱湍理论,我们研究了极端相对论电子团在喷流等离子体中的辐射过程,并详细研究了它在解释Blazar天体辐射特性中的应用,本文认为,Blazar天体的不稳定辐射与极端相对论电子团的无规注入、喷流等离子体的物理环境瞬息变化有关。Blazar中快速变化的辐射偏振角摆动。产生于相对论电子团在湍动等离子体中的同步辐射过程。另外,X选和射电选的BLLac天体之间的区别取决于喷流等离子体的运动状态和物理环境。 相似文献
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The Doppler Effect and Spectral Energy Distribution of Blazars 总被引:2,自引:0,他引:2
The relativistic beaming model is adopted to discuss quantitatively the observational differences between radio-selected BL Lac objects (RBLs) and X-ray-selected BL Lac objects (XBLs), and between BL Lac objects and flat spectrum radio quasars (FSRQs). The main results are the following:(1) In the Doppler corrected color-color(αro^in-αox^in) diagram,XBLs and FSRQs occupy separated regions, while RBLs bridge the gap between them. These properties suggest that similar intrinsic physical processes operate in all the objects under a range of intrinsic physical conditions. (2) Our results are consistent with the results of Sambruna, Maraschi and Urry (1996) from other methods. We show the αxox introduced by Sambruna to be a good index for describing the energy distribution because it represents the intrinsic energy distribution and includes the Doppler correction. (3)The Doppler effect of relativistic beaming is the main mechanism, and the physical differences(such as magnetic fields, electron energies) are also important complementary factors for understanding the relation between XBLs and RBLS. 相似文献
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110个梅西叶天体,是天文爱好者最乐于观测的深空天体目标。你可能观测过其中的一部分天体,但你有没有想过进行这样一个挑战:在一晚上的时闻里,观测尽量多的、甚至全部的梅西叶天体?这项观测运动,称之为梅西叶天体马拉松(下文简称“梅马”)。 相似文献
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Yan-Xia Zhang Yong-Heng ZhaoNational Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2003,3(2):183-190
The sizes of astronomical surveys in different wavebands are increasing rapidly. Therefore, automatic classification of objects is becoming ever more important. We explore the performance of learning vector quantization (LVQ) in classifying multi-wavelength data. Our analysis concentrates on separating active sources from non-active ones. Different classes of X-ray emitters populate distinct regions of a multidimensional parameter space. In order to explore the distribution of various objects in a multidimensional parameter space, we positionally cross-correlate the data of quasars, BL Lacs, active galaxies, stars and normal galaxies in the optical, X-ray and infrared bands. We then apply LVQ to classify them with the obtained data. Our results show that LVQ is an effective method for separating AGNs from stars and normal galaxies with multi-wavelength data. 相似文献