共查询到20条相似文献，搜索用时 171 毫秒
1.
本文第1部份,描述从SAS-2卫星得到的能量大于100MeV的宇宙Υ射线数据来证认有Υ射线的活动星系核。11个类星体、3个BLLac天体和1个射电星系的Υ射线辐射已得到证认。 本文第2部分描述活动星系核对河外Υ射线背景辐射的影响。SAS-2的Υ辐射数据,已被用来测定类星体和赛弗特星系的Υ辐射绝对光度与光学绝对光度间的函数关系,并由此导出它们对河外Υ射线背景辐射的贡献。我们指出,类星体(B<20)、赛弗特星系(1型和1.5型)对35—100MeV能量范围的弥散Υ射线背景辐射有相当大的贡献(59％)。由此我们得出河外Υ射线背景辐射可能是由类星体和赛弗特星系这类活动星系产生的结论。 本文第3部份我们对3个有Υ辐射的活动星系核综合其Υ波段和其他波段的数据,以探索这些天体辐射的发射机制。这些综合的数据对发射机制给出严格的限制。我们指出,对这3个天体的数据,与同步自康普顿模型(SSC)的预计是一致的。 相似文献
2.
新发现的4个X选类星体和2个赛弗特星系 总被引：2，自引：1，他引：1
１９９７－１９９８年期间,使用２．１６ｍ望远镜对ＲＯＳＡＴ Ｘ射线源进行光学证认,证认出４个ＲＯＳＡＴ Ｘ射线源是新发现的类星体,２个ＲＯＳＡＴ Ｘ射线源是新发现的赛弗特星系。 相似文献
3.
研究表明活动星系核的高能γ射线辐射和低频射电辐射有着某些内在的联系。ＥＧＲＥＴ已检测到６６ 颗可信度很高的活动星系核。而这些高能的活动星系核有部分缺少足够的射电图象观测。为研究这些河外剧变源的射电辐射性质及致密结构,并研究活动量系核射电喷流弯曲与高能辐射的内在联系。我们利用国际欧洲ＶＬＢＩ网,英国的ＭＥＲＬＩＮ 和美国的ＶＬＡ对近２０ 颗γ射线活动星系核进行了观测。本文给出部分高能γ射线活动星系核在８ ．５ＧＨｚ的ＶＬＡ 观测图象。 相似文献
4.
１９９５年５月，使用２．１６ｍ望远镜对ＲＯＳＡＴ Ｘ射线源进行光学证认期间，发现８个ＲＯＳＡＴ Ｘ射线源和５Ｇ射电源的光学对应体是以前未发现的类星体，其红移范围从０．３３３至１．０９１。本文给出了这些类星体的多波段特性。 相似文献
5.
１９９５年５月，使用２．１６ｍ望远镜对ＲＯＳＡＴＸ射线源进行光学证认期间，发现８个ＲＯＳＡＴＸ射线源和５Ｇ射电源的光学对应体是以前未发现的类星体，其红移范围从０．３３３至１．０９１。本文给出了这些类星体的多波段特性。 相似文献
6.
7.
利用Ｒ（红）－Ⅰ（近红外）两色照相测光方法，搜寻银道整天区的红外超天体，并证认ＩＲＡＳ点源的红外超对应体。本是一组系列章的第四篇。在矩尺天区发现了１９５个红外超天体，并证认出其中２２个是ＩＲＡＳ点源的对应体。 相似文献
8.
9.
晚型星计算机自动光谱分类 总被引：1，自引：1，他引：0
在对恒星形成区（ＳＦＲ）中ＲＯＳＡＴ选弱发射线Ｔ Ｔａｕｒｉ星（ＷＴＴＳ）进行光谱证认的过程中,发展了一套基于北京天台２．１６米光学望远镜及其ＯＭＲ卡焦光谱仪系统的晚型星中色散（５０Ａ／ｍｍ）光谱计算机自动光谱分类方法。对ＲＯＳＡＴ选ＷＴＴＳ候选体中晚型星进行自动光谱分类的结果表明,一般情况下,光谱型的分类精度可达±１个次级,个别源为±２个次级。该自动光谱分类方法同时适用于其它光谱晚型星。 相似文献
10.
这里叙述的新发现仅指某一特殊类型的发现（如新星，超新星和小行星等）及某一特殊类型天体的认证（如X射线源证认为类星体等），而不包括某一类天体的某种天象及未知性质源的列表（如深度成像观测得到的前人没有纪录过的一般天体，如恒星，但一些特殊天体亦列入），由于收集不全面和所谓“发现”定义的困难，向有发向而未列入者先歉意。从80年代后期开始，我国的观测设备有了很大垢发展，所以有一批重的的天文发现，为天文提供了很好的机会，它包括下面几方面，层系层次天体：（1）用X射线源和射电源证认了一批包括类星体，BL Lac天体，赛弗特天体在内的活动星系核；（2）用IRAS源证认了一批W－R星系；（3）BATC巡天在一个星系周围发现了一个“环”。恒星层次天体：（1）河外星系中发现了一批超新星的一个新星，（2）发现了和用ROSAT源证认了一批激变变星，（4）BATC和超新星巡天发现了一批变星，（4）发现了若干新的δSct变星，（5）发现了一批Herbig-Haro天体，（6）发现了一批水脉泽。行星层次天体：（1）发现了大批小行星，特别是有些是近地不行星，（20发现若干彗星。 相似文献
11.
C. de Vegt J. A. Hughes D. Jauncey G. White K. J. Johnston J. Russell G. Nicholson 《Astrophysics and Space Science》1991,177(1-2):199-202
An observational pilot program is described which provides a first step towards the construction of an inertial extragalactic reference frame from optical and radio measurements. Candidate objects will be selected from extragalactic compact radio sources which display optical counterparts. Galactic radio stars will be secondary reference objects. The reference frame will be defined by the radio positions of the extragalactic objects. Based on a coordinated effort in both hemispheres, a global homogeneous net of about 400 quasars and 100 radio stars is expected to result from a five year campaign. 相似文献
12.
D. I. Karasev A. A. Lutovinov A. Yu. Tkachenko G. A. Khorunzhev R. A. Krivonos P. S. Medvedev M. N. Pavlinsky R. A. Burenin M. V. Eselevich 《Astronomy Letters》2018,44(8-9):522-540
We present the results of our optical identifications of several hard X-ray sources from the INTEGRAL all-sky survey obtained over 14 years of observations. Having improved the positions of these objects in the sky with the X-ray telescope (XRT) of the Swift observatory and the XMMNewton observatory, we have identified their counterparts using optical and infrared sky survey data. We have obtained optical spectra for more than half of the objects from our sample with the RTT-150 and AZT-33IK telescopes, which have allowed us to establish the nature of the objects and to measure their redshifts. Six sources are shown to be extragalactic in origin and to belong to Seyfert 1 and 2 galaxies (IGR J01017+6519, IGR J08215-1320, IGR J08321-1808, IGR J16494-1740, IGR J17098-2344, IGR J17422-2108); we have failed to draw definitive conclusions about the nature of four more objects (IGR J11299-6557, IGR J14417-5533, IGR J18141-1823, IGR J18544+0839), but, judging by circumstantial evidence, they are most likely also extragalactic objects. For one more object (IGR J18044-1829) no unequivocal identification has been made. 相似文献
13.
C. R. Kerton 《Monthly notices of the Royal Astronomical Society》2006,373(3):1203-1212
Arcminute-resolution radio continuum images at 408 and 1420 MHz from the Canadian Galactic Plane Survey (CGPS) have been used to re-examine radio sources listed in the Kallas & Reich catalogue. This catalogue is of particular interest to Galactic studies as it lists both extended and compact radio sources found in the second Galactic quadrant. We have determined the nature (extended versus compact, Galactic versus extragalactic) of all of these bright radio sources. A number of large H ii regions with no optical counterparts are highlighted along with a sample of large radio galaxies. Many sources previously thought to be extended Galactic objects are shown to be point sources. A sample of point sources with flat or rising spectra between 408 and 1420 MHz has been compiled, and within this sample likely Gigahertz Peaked Spectrum sources have been identified. 相似文献
14.
Alessandro Marconi Roberto Maiolino Romain G. Petrov 《Astrophysics and Space Science》2003,286(1-2):245-254
Interferometry in the optical and near infrared has so far played a marginal role in Extragalactic Astronomy. Active Galactic
Nuclei are the brightest and most compact extragalactic sources, nonetheless only a very limited number could be studied with
speckle interferometry and none with long baseline interferometry. The VLTI will allow the study of moderately faint extragalactic
objects with very high spatial resolution thus opening a new window on the universe. With this paper we focus on three scientific
cases to show how AMBER and MIDI can be used to tackle open issues in extragalactic astronomy.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
Low surface brightness clouds observed at optical, infrared, and radio wavelengths are discussed. We present evidence that some clouds at high galactic latitudes are associated with the Local Group, M81, and possibly even with higher redshift extragalactic objects.Low temperature clouds at high latitude must affect at some level the short wave length side of the cosmic background radiation. If some of these clouds are extragalactic there should be a further effect on the interpretation of CBR measures. 相似文献
16.
E. A. Gonzalez-Solares I. Perez-Fournon M. Rowan-Robinson S. Oliver M. Vaccari C. Lari M. Irwin R. G. McMahon S. Hodgkin P. Ciliegi S. Serjeant C. J. Willott 《Monthly notices of the Royal Astronomical Society》2005,358(2):333-340
We present the multiwavelength properties and catalogue of the 15 μm and 1.4 GHz radio sources detected in the European Large Area ISO Survey ( ELAIS ) areas N1 and N2. Using the optical data from the Wide Field Survey we use a likelihood ratio method to search for the counterparts of the 1056 and 691 sources detected at 15 μm and 1.4 GHz, respectively, down to flux limits of S 15 = 0.5 mJy and S 1.4 GHz = 0.135 mJy . We find that ∼92 per cent of the 15 μm ELAIS sources have an optical counterpart down to r '= 24 . All mid-infrared (IR) sources with fluxes S 15 ≥ 3 mJy have an optical counterpart. The magnitude distribution of the sources shows a well-defined peak at relatively bright magnitudes r '∼ 18 . The mid-IR-to-optical and radio-to-optical flux diagrams are presented and discussed in terms of actual galaxy models. About 15 per cent of the sources are bright galactic stars; of the extragalactic objects ∼65 per cent are compatible with being normal or starburst galaxies and ∼25 per cent active galactic nuclei (AGNs). Objects with mid-IR-to-optical fluxes larger than 100 are found, comprising ∼20 per cent of the sample. We suggest that that these sources are highly obscured luminous and ultraluminous starburst galaxies and AGNs. 相似文献
17.
R. R. Sefako I. S. Glass D. Kilkenny O. C. De Jager R. S. Stobie D. O'Donoghue C. Koen 《Monthly notices of the Royal Astronomical Society》1999,309(4):1043-1050
In an attempt to discover new southern BL Lac objects, 14 optically featureless objects from the Edinburgh–Cape Survey were selected. Optical polarimetry and spectroscopy, radio and IR observations were carried out in order to improve their classifications. The 14 objects were examined according to special criteria that are described. Their UBV and JHK colour–colour distributions, spectrograms, radio observations and visible-region polarimetry were utilized to conclude that the selected objects are not BL Lacs. Most of them are apparently not extragalactic objects. It is suggested that four of the 14 candidates are DC white dwarfs, one is a QSO, three are DA white dwarfs or sdB subdwarfs, one is a cataclysmic variable, one is a DAO/sdO and another is possibly a DA+dM binary (composite system with a 'primary' hot white dwarf and a 'secondary' M-type main-sequence dwarf) or a cataclysmic variable. One object is likely to be a subdwarf, while two remain unclassifiable. 相似文献
18.
The distribution of relative position angles between the integrated intrinsic polarization (perpendicular to the direction of the intrinsic magnetic field) and the major axis of an extragalactic radio source were studied for different types of radio sources. Data for 280 extragalactic radio sources were used and it was found that there are large differences in the relative orientation of different types of radio sources. The directions of the intrinsic integrated magnetic fields correlate with the major radio axes of more elongated radio sources (K > 2.5, where K is the ratio of lengths of the major and minor axes of the radio images) and for radio sources of type FR II, whereas for less elongated objects (K < 2.5) and for radio sources of type FR I the magnetic fields do not correlate at all with the radio axes. An alternative mechanism for the formation of a radio galaxy from relativistic plasma ejected from the central part of an optical galaxy and moving in its large-scale, dipole magnetic field may be a theoretical basis for classification with respect to the elongation parameter K of the radio image. 相似文献
19.
M. V. Sazhin O. S. Khovanskaya M. Capaccioli G. Longo J. M. Alcalá R. Silvotti M. V. Pavlov 《Astronomy Letters》2005,31(2):73-79
We consider additional arguments in favor of the first observable cosmic string. We discuss candidates for gravitational lensing events near the extragalactic double source CSL-1 (Capodimonte-Sternberg-Lens Candidate no. 1) discovered in the Osservatorio Astronomico di Capodimonte Deep Field (OACDF). The detected excess of candidates for such events cannot be explained in terms of the theory of gravitational lensing by standard extragalactic objects (galaxies, groups of galaxies, etc.) and is in close agreement with the proposed model of gravitational lensing by a cosmic string. 相似文献
20.
We present a study of the statistical properties of extragalactic objects, the differential log N−log S curves in various wavelength intervals in the region of the so-called Cold Spot found on the CMB maps. An analysis of the
distributions obtained shows that the evolutionary properties of extragalactic objects (source counts) in the Cold Spot region
do not differ from the corresponding properties in other space regions. Such a pattern could be expected if the spot is formed
due to a topological defect, namely, a texture. 相似文献