Orbital Elements of 2004 Perseid Meteoroids Perturbed by Jupiter     

Josep Maria Trigo-Rodriguez  Jeremie Vaubaillon  José Luís Ortiz  Alberto Castro-Tirado  Jordi Llorca  Esko Lyytinen  Martin Jelínek  Antonio de Ugarte Postigo  Pablo Santos Sanz  Francisco J. Aceituno Castro  Albert Sánchez Caso  Antonio Bernal González  Juan Pastor Erades  Francisco Ocaña 《Earth, Moon, and Planets》2005,97(3-4):269-278

Jupiter and Saturn produce important gravitational impulses on meteoroids released by comet 109P/Swift-Tuttle. The meteoroids from this comet once released follow retrograde orbits that during their periodic approaches to these planets (within 1.6 and 0.9 A.U., respectively) are impulsed gaining orbital energy. This perturbation effect is translated into a net inward shift in the node of the perturbed meteoroids. Such geometry with Jupiter occurred in 2004 over a meteoroid trail ejected by this comet during the 1862 A.D. return of the comet to perihelion. In order to study the predicted outburst produced by one-revolution meteoroids, the Spanish Photographic Meteor Network (SPMN) performed an extensive campaign. As a part of this observational effort here are presented 10 accurate meteoroid orbits. We discuss their origin by comparing them with the theoretical orbital elements of the dust trails intercepting the Earth during the 2004 Perseid return.  相似文献   

Monte-Carlo Simulations of Cosmic-ray and Internal Radiation Effects on ISOCAM on Board ISO     

Arnaud Claret  Hervé Dzitko 《Experimental Astronomy》2002,13(3):135-152

One of the main limitations to the sensitivity of the infrared camera ISOCAM on-board the Infrared Space Observatory (ISO) comes from responsivity variations and glitches caused by the impacts of charged particles in photo-detectors. Glitch rate measurements, glitch properties and removal methods have already been addressed during the first ISO detector workshop(Madrid, 1998) and published in a special issue of Experimental Astronomy. It appeared that glitch rate and most of glitch properties could be reproduced by Monte-Carlo simulations. This is very interesting in order to predict before launch the effect of charged particles in photo-detectors operated in space. This paper presents results of Monte-Carlo simulations of radiation effects on ISOCAM detectors. Glitch rates, spatial and energetic properties of glitches have been computed and are compared with measured values. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Estimates of AGN Black Hole Mass and Minimum Variability Timescale   总被引：4，自引：0，他引：4  

Guang-Zhong Xie  Luo-En Chen Huai-Zhen Li  Li-Sheng Mao  Hong Dai  Zhao-Hua Xie  Li Ma  Shu-Bai Zhou National Astronomical Observatories  Yunnan Observatory  Chinese Academy of Science  Kunming  Yunnan Astrophysics Center  Yunnan University  Kunming Physics Department  Yunnan Normal University  Kunming Physics Department  Yuxi Normal College  Yuxi Graduate University of Chinese Academy of Sciences  Beijing 《中国天文和天体物理学报》2005,5(5):463-470

Black hole mass is one of the fundamental physical parameters of active galactic nuclei (AGNs), for which many methods of estimation have been proposed. One set of methods assumes that the broad-line region (BLR) is gravitationally bound by the central black hole potential, so the black hole mass can be estimated from the orbital radius and the Doppler velocity. Another set of methods assumes the observed variability timescale is determined by the orbital timescale near the innermost stable orbit around the Schwarzschild black hole or the Kerr black hole, or by the characteristic timescale of the accretion disk. We collect a sample of 21 AGNs, for which the minimum variability timescales have been obtained and their black hole masses (Mσ) have been well estimated from the stellar velocity dispersion or the BLR size-luminosity relation. Using the minimum variability timescales we estimated the black hole masses for 21 objects by the three different methods, the results are denoted by Ms, Mk and Md, respectively. We compared each of them with Mσindividually and found that: (1) using the minimum variability timescale with the Kerr black hole theory leads to small differences between Mσand Mk, none exceeding one order of magnitude, and the mean difference between them is about 0.53 dex; (2) using the minimum variability timescale with the Schwarzschild black hole theory leads to somewhat larger difference between Mσand Ms: larger than one order of magnitude for 6 of the 21 sources, and the mean difference is 0.74 dex; (3) using the minimum variability timescale with the accretion disk theory leads to much larger differences between Mσand Md, for 13 of the 21 sources the differences are larger than two orders of magnitude; and the mean difference is as high as about 2.01 dex.  相似文献   

微波爆发区的日冕磁场研究     

周爱华  傅其骏 《天文学进展》1996,14(4):297-301

回顾了日冕磁的研究历史，介绍了我们首镒提出的日冕磁场的微波诊断方法及其应用的带来的启迪，提出进一步开展日冕磁场及其相关研究的建议。  相似文献   

A model of rotating hotspots for the 3 : 2 frequency ratio of high-frequency quasi-periodic oscillations in black hole X-ray binaries     

Ding-Xiong Wang  Yong-Chun Ye  Guo-Zheng Yao  Ren-Yi Ma 《Monthly notices of the Royal Astronomical Society》2005,359(1):36-42

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Parallels plane projection and its geometric features     

Zhou  ChengHu  Ma  Ting  Yang  Liao  Qin  Biao 《中国科学:地球科学(英文版)》2007,50(1):176-180

A new equivalent map projection called the parallels plane projection is proposed in this paper. The transverse axis of the parallels plane projection is the expansion of the equator and its vertical axis equals half the length of the central meridian. On the parallels plane projection, meridians are projected as sine curves and parallels are a series of straight, parallel lines. No distortion of length occurs along the central meridian or on any parallels of this projection. Angular distortion and the proportion of length along meridians (except the central meridian) introduced by the projection transformation increase with increasing longitude and latitude. A potential application of the parallels plane projection is that it can provide an efficient projection transformation for global discrete grid systems.

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天鹅座X-1硬X射线的能量谱     

马宇蒨  李光华  张承模  钱跃民  肖谦益  陆柱国  吴枚  戴长江  李惕碚  顾逸东  张希元 《中国天文和天体物理学报》1989,(4)

1985年9月22日,我们用空间硬X射线望远镜HAPI-2,在我国的高空气球上,对天鹅座X-1进行了观测,望远镜几何面积为140cm~2,观测能区20—200keV,空间定向精度±0.2°。获得的硬X射线能谱陡,总辐射能流LX～1.0×1~(37)erg/sec,低于常规态。本文将介绍望远镜的性能和观测过程,能谱分析的结果,并对当时天鹅座X-1可能的“态”进行讨论。  相似文献   

Light curves of the eclipsing systems of RS CVn-type     

María Lina Berríos-Salas  Margarita Guzmán-Vega  José Fernández-Labra  Manlio Maldini-Sánchez 《Astrophysics and Space Science》1989,162(2):205-209

This work presents the light curves for rotating spotted stars generated by a computational code developed by us. This code is based in a model of the system and its analytical solution. The work also present an analysis of the photometric curve variations with the changes in the model's parameters.As a first result we have simulated a temporal evolution of the light curve when the photospheric spot varies its size and position and we reproduced some observational light curves of the II Peg star.Work supported by Dirección de Investigación, Universidad de La Serena, Chile.  相似文献   

Correlation of hard X-ray and type III bursts in solar flares     

Vahé Petrosian  John Leach 《Solar physics》1983,87(1):165-175

The observed correlations between X-ray and type III radio emissions from solar bursts are described by means of a bivariate distribution function. Procedures for determining the form of this distribution are described using a sample of data analyzed by Kane (1981). With the help of this distribution a model is constructed to explain the correlation between the X-ray spectral index and the ratio of X-ray to radio intensities. Implications of the model are discussed.  相似文献   

Heat balance for the high-temperature component of a solar flare     

André Duijveman 《Solar physics》1983,84(1-2):189-203

Shortly after the occurrence of the impulsive spikes of the two-ribbon flare of May 21, 1980, a temperature analysis of the X-ray emitting flare plasma showed the presence of a low-temperature component [n = 15 × 10¹⁰ cm^#X2212;3; T = 20 × 10⁶ K] and a high-temperature component [n = 2 × 10¹⁰ cm^#X2212;3; T = 40 × 10⁶ K]. The mean free path of an electron in the hot component is comparable to the size of the source (≈ 10⁴ km). Heat losses from the hot source can therefore not be described with classical formulae. Theoretical arguments show that most likely the electron to ion temperature ratio T _e/T_i in the hot plasma is close to unity. This implies the presence of a hot ion component (T _i ≈ 40 × 10⁶ K) as well. Under these conditions (T _e ≈ T _i) heat flux limitation by electrostatic turbulence is ineffective. However, reduction of the heat flux is still possible due to the breakdown of classical theory. It is demonstrated that only non-classical current dissipation processes can sustain a hot source against cooling by a saturated heat flux. Investigation of the collisionality as a function of position along a magnetic loop shows that the breakdown of classical theory should be expected to occur first near the base of the loop. We conclude that the newly discovered hot source is important for the energy budget of the flare, even if the heat losses are considerably reduced. It is estimated that for the May 21, 1980 flare a total of about 10³¹ ergs were necessary to maintain the hot source against heat losses over the time period that it was observed (≈ 10 min).  相似文献