Discovery of Five Narrow－Line Seyfert 1 Galaxies and Implications on the NLS1 Model     

Jiang-Hua Wu  Xiang-Tao He  Yang Chen  Wolfgang Voges 《中国天文和天体物理学报》2003,3(5):423-430

We report the discovery of five Narrow-Line Seyfert 1 galaxies (NLSls) identified from the ROSAT All-Sky Survey bright sources. One of them has a quasarlike luminosity and two, including the quasar-like one, have close companions and/or show interacting features. We calculate the central black hole masses and Eddington ratios for the five NLSls. In combination with the objects of Kaspi et al., we find that NLSls have smaller central black hole masses and higher accretion rate than normal Seyfert ls.  相似文献   

High resolution spectra of galaxies     

Pierre Ocvirk  Ariane Lançon  Christophe Pichon  Philippe Prugniel  Damien Le Borgne  Brigitte Rocca-Volmerange  Michel Fioc  Caroline Soubiran  Eric Thiébaut 《Astrophysics and Space Science》2003,284(2):933-936

We present inversion techniques which aim at recovering the composite nature and the kinematics of a stellar population from its high resolution absorption line spectrum. The originality of the combined inversion is its potential to recover both the stellar content and the kinematics simultaneously. These techniques use new synthetic high resolution spectra produced by PéGASE and minimization algorithms. We apply them to mock data representing the bulge and disk population of the inner region of spiral galaxies. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

A survey searching for the epoch of assembling of Hubble types     

DuÍlia F. de Mello  Anna Pasquali 《Astrophysics and Space Science》2003,284(2):389-392

We have started a survey of galaxies at intermediate redshifts using the HST-STIS parallel fields. Our main goal is to analyse the morphology of faint galaxies in order to estimate the epoch of formation of the Hubble classification sequence. The high resolution of STIS images (0.05″) is ideal for this work and enables us to perform a morphological classification and to analyse the internal structures of galaxies. We find that 40% of the 290 galaxies are early types and that there are more irregulars and ellipticals at the fainter magnitudes. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

The Nature of Submillimetre Galaxies     

Ian Smail 《Astrophysics and Space Science》2002,281(1-2):453-456

I present a brief summary of the results from extensive multi-wavelength observations of the submillimetre-selected galaxies. I discuss the properties of this population, in particular their interpretation within the framework of our understanding of galaxy formation and evolution. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

在NGC1068附近发现的一个新的类星体     

朱杏芬  张昊彤  褚耀泉 《天文学报》2001,42(3):240-242

塞佛特星系ＮＧＣ1 0 6 8是一个非常令人注目的特殊天体 ,它是Ｓｅｙｆｅｒｔ[1]发现的第一批此类星系中离我们最近 (1 9Ｍｐｃ,取Ｈ0 =6 0ｋｍｓ- 1Ｍｐｃ- 1)和最亮的一个塞佛特星系 ,因此天文学家从射电到Ｘ 射线整个电磁波段对它进行了详尽的观测和研究。ＮＧＣ1 0 6 8最初被归类为塞佛特ＩＩ型天体 ,但是通过对其偏振光的光谱观测 ,发现了认为被遮挡住的塞佛特Ｉ型核发出的± 432 0ｋｍ/ｓ的宽Ｈβ发射线 ,因此被认为是活动星系核统一模型的一个范例 (见文 [2 ] )。射电与光学的观测资料都表明ＮＧＣ1 0 6 8的中心部分有激烈的喷射活动…  相似文献   

Comparison of stellar orbits in various models of the galaxy     

S. Ninković  V. V. Orlov  A. V. Petrova 《Astronomy Letters》2002,28(3):163-168

We compare the properties of orbits in five different rotationally symmetric models of the regular Galactic force field. Our goal is to estimate the possible range of the discrepancies in stellar orbital elements attributable to the choice of the model for the Galactic potential. For disk objects, the discrepancies in eccentricities e attributable to the choice of the model do not exceed 0.05. The relative distances h from the symmetry plane can differ by more than a factor of 2. Since there are resonance regions, the types of orbits (box-shaped or tube-shaped) cannot be reliably identified. The situation is even worse for halo objects: the discrepancies in h can exceed 100%, and identifying the type of orbits is also highly problematic.  相似文献   

晚型星系金属丰度与自转速度的关系   总被引：1，自引：0，他引：1  

罗智坚  傅莉萍  束成钢  赵君亮 《天文学进展》2004,22(1):71-80

星系物质化学组成的研究不仅对于理解有关星系形成和演化的各种物理过程具有重要意义，而且还可以对星系形成和演化的各种理论模型提供重要的约束。随着观测技术及理论工作水平的不断提高，利用星系的大量观测资料来系统地研究星系化学组成与星系宏观性质之间的关系将成为可能。星系金属丰度与光度之间的强相关性以及晚型星系金属丰度与自转速度的关系即是其中最有意义的内容之一。全面回顾了星系金属丰度与星系宏观观测性质间关系的研究历史，重点评述了晚型星系金属丰度与自转速度关系的最新研究进展，详细讨论了目前对此类关系的物理解释及其对星系形成和演化模型的影响。  相似文献   

2Mass Observation Of Infrared Quasars     

Pei-sheng Chen  Hong-guang Shan  Pin Zhang  Yi-fei Gao 《Astrophysics and Space Science》2006,302(1-4):17-25

The 2MASS observation of the infrared quasars (IR QSOs) known so far is presented in this paper. Compared with the optical selected quasars, infrared quasars are more dust-enshrouded and have redder colors and steeper spectral indices in the near infrared. In consequence, they are much younger than the optical selected quasars. The result may be helpful to the suggestion that the evolution links could be the ULIRGs - > the IR QSOs - > the optical selected quasars. This publication makes use of data products from the Two Micron All Sky Survey (2MASS), which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center, funded by the National Aeronautics and Space Administration and the National Science Foundation of the United States.  相似文献   

Diffuse Baryons in Cosmic Structures     

Alfonso Cavaliere 《Astrophysics and Space Science》2004,294(1-2):109-124

I review the processes that govern the amount and the thermal state of the hot plasma pervading clusters and groups of galaxies: the gravitational heating driven by the DM merging histories, the radiative cooling of baryons, and the energy fed back by SNe and by AGNs or quasars. I argue that the X-ray emissions and the entropy levels now observed from clusters to groups require the AGNs to contribute substantially to preheat the gas before it falls into clusters, and the quasars to blow some plasma out of groups and galaxies.  相似文献   

The spatial correlation function of cD Abell clusters     

Gao Yu  Zhou You-yuan 《Chinese Astronomy and Astrophysics》1988,12(4):279-282

We calculated the spatial two-point correlation function of cD clusters in Abell's statistical sample using estimated redshifts and found that positive correlation exists on all scales except around 70 Mpc and 170 Mpc (H₀ = 100 km s⁻¹ Mpc⁻¹). In particular, positive correlation persists on the super large scale around 300 Mpc. This is particularly interesting in view of the known relationships among cD clusters, radio sources and superclusters.  相似文献