共查询到20条相似文献，搜索用时 109 毫秒
1.
为了研究亮红外星系中分子气体的物理性质,本论文给出了一个小样本近邻亮红外星系初步的观测结果、一个高红移星系IRAS F10214+4724的详细研究以及一个近邻亮红外星系ARP 302的高分辨研究.另外,对Perseus星系团中存在的分子气体给出了高分辨的观测,并研究其气体的运动学状态.对一个小样本的亮红外星系,得到了CO(J=3→2)的成图结果,揭示其气体分布都集中在星系中心或者是并合星系的中心及其星系核的重叠区域.对于其中的一个源NGC 3256,给出了其CO(J=3→2)、 相似文献
2.
利用SDSS光谱,研究了IRAS卫星亮红外源星表中的盘状星系中的恒星形成性质,并着重探讨了棒对星系核区恒星形成活动的影响.利用星族合成的方法得到了每个样本星系核区的恒星组成性质、恒星形成活动的强度等信息,并比较了星系整体和核区恒星形成性质的差异.得到的结论:除去相互作用,样本中的棒星系显示出比非棒旋星系更强的核区恒星形成活动和更多的年轻星族成分. 相似文献
3.
4.
5.
本文对河外IRAS源的最新研究成果作了评述。介绍了河外IRAS源的空间分布,并着重介绍了河外IRAS源中的星暴现象和活动星系核以及它们之间可能存在的联系. 相似文献
6.
使用澳大利亚致密阵 (ATCA)在 1 .4GHz上观测了一个极高光度的IRAS星系样本。在这个样本所包括的 3 7个IRAS星系中 ,探测到 1 9个源的射电发射 ,获得了它们的射电参数 ,如峰值位置 ,射电流量等。该样本的射电功率范围在 2 2 .9相似文献
7.
通过利用CANDELS-EGS(Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey-Extended Groth Strip)场中HST WFC3(Hubble Space Telescope Wide Field Camera 3)F160W高分辨率的观测图像,研究了9个光谱红极亮红外星系的形态结构特征.发现这些星系的形态表现出多样性(从椭圆到多个亮核或弥散的结构),如:双核,气体桥,双不对称体,不规则或椭圆结构.为了定量地研究这些极亮红外星系的形态,测量了它们在静止光学波段的形态参数(基尼系数G和矩指数M20).与近邻极亮红外星系相比,高红移极亮红外星系的G偏小而M20偏大,表明这些星系的星族分布聚集度小且不对称性大.基于对样本中极亮红外星系2维面亮度轮廓的拟合,得到这些星系的有效半径分布在2.4 kpc到5.8 kpc之间,其平均值是(3.9±1.1)kpc.相比较于近邻相似质量的恒星形成星系来说,高红移极亮红外星系的平均大小要小1到2倍.在类似红移和红外光度条件下,得出的这些结果也与其它文献中给出的结论相一致. 相似文献
8.
从Sloan数字巡天第2批释放的数据(SDSS DR2)中选择了395个在r波段亮于15等的面向晚型旋涡星系作为样本,研究了盘的颜色梯度与结构参数的关系.结果表明:盘的颜色梯度与盘的绝对星等(质量)无关;盘的颜色梯度与盘的尺度有关,越大的盘颜色梯度越陡;盘的颜色梯度与盘的颜色有关,越蓝的盘颜色梯度越陡;盘的颜色梯度与盘的表面亮度有关,越亮的盘颜色梯度越陡,并简单讨论了盘的颜色梯度与各结构参数的相关关系对晚型旋涡星系盘恒星形成历史的约束. 相似文献
9.
IRAS在12,25,60和100μm的巡天,给我们提供了研究各类星系红外辐射特性的可能。为了研究具有尘带的E和SO星系的红外辐射特性,我们利用了E.Sadler给出的完备的E和SO星系表。在该星系表中共列出248个夭体,其中38个被证记为IRAS点源,且又有确切的60和100μm的流量值。在这38个天体中有6个被列在K.Ebneter和B.Balik最新发表的具有全带的椭圆星系表中。我们以这6个星系作为具有尘带的E和SO星系的样本,其它32个没有尘带的E和SO星系即作为对照样本。为了讨论具有尘带的椭圆星系的红外辐射特性,我们利用非参数Mann-Whitney检验,对这两个样本的LIR和FIR/FB的分布作了讨论,结果是在对于置信度α=0.05的水平上,我们不能拒绝另一假设:这两个样本的LIR和FIR/FB的分布是相同的。对于同时具有25,60和100μm确切流量的E和SO星系我们讨论了它们的双色图,结果发现,不具尘带的E和SO星系都处于Rowan-Robinson.et al所指出的正常星系区,而一些具有尘和带的ESO星系,则远离这一区域,它们是LINER和SEYFERT星系。 相似文献
10.
11.
For four selected fields in the Catalogue of IRAS Faint Sources we have calculated the two-point correlation function of the galaxies and the correlation fractal dimension. The results show that the galaxies in all the fields are clustered on small angular scales. On larger scales, the distribution can be well expressed by a multi-level fractal. On still larger scales, possible typical scales can be detected using un-normalized pair counts. The average results for the four fields are consistent with previous results for the all-sky IRAS point sources and other sky surveys. 相似文献
12.
We present upper limits on the 850-μm and 450-μm fluxes of the warm hyperluminous (bolometric luminosity galaxies IRAS P09104+4109 and IRAS F15307+3252 , derived from measurements using the SCUBA bolometer array on the James Clerk Maxwell Telescope. Hot luminous infrared sources like these are thought to differ from more normal cold ultraluminous infrared galaxies in that they derive most of their bolometric luminosities from dusty active galactic nuclei (AGNs) as opposed to starbursts. Such hot, dusty AGNs at high redshift are thought to be responsible for much of the mass accretion of the Universe that is in turn responsible for the formation of the supermassive black holes seen in the centres of local galaxies. The galaxy IRAS P09104+4109 is also unusual in that it is a cD galaxy in the centre of a substantial cooling-flow cluster, not an isolated interacting galaxy like most ultraluminous infrared galaxies. Previously it was known to have large amounts of hot dust from IRAS observations. We now show that the contribution of cold dust to the bolometric luminosity is less than 3 per cent. Most ultraluminous infrared galaxies possess large amounts of cold dust, and it is now known that some cooling-flow cluster cD galaxies do as well. Yet this object, which is an extreme example of both, does not have enough cold gas to contribute significantly to the bolometric luminosity. We outline physical reasons why this could have happened. We then provide a discussion of strategies for finding hot dusty AGNs, given the limitations on submillimetre surveys implied by this work. 相似文献
13.
本文对ＩＲＡＳ暗源表中４个选区内的ＩＲＡＳ星系的两点角相关函数，关联分维进行了计算。结果表明，所有选区内的星系呈现小角尺度上的成团。在较大角尺度上，分布可以用多级分形很好地表示。在更大角尺度上，用非归一星系对计数可以探测到密度分布中可能存在的典型尺度。当取４个选区的平均值作为ＩＲＡＳ星系在宇宙中分布情况的代表时，所得结果与用全天ＩＲＡＳ点源表和其他巡天资料得到的结果一致。 相似文献
14.
Loretta Dunne Stephen A. Eales 《Monthly notices of the Royal Astronomical Society》2001,327(3):697-714
This is the second in a series of papers presenting results from the SCUBA Local Universe Galaxy Survey. In our first paper we provided 850-μm flux densities for 104 galaxies selected from the IRAS Bright Galaxy Sample and we found that the 60-, 100-μm ( IRAS ) and 850-μm (SCUBA) fluxes could be adequately fitted by emission from dust at a single temperature. In this paper we present 450-μm data for the galaxies. With the new data, the spectral energy distributions of the galaxies can no longer be fitted with an isothermal dust model – two temperature components are now required. Using our 450-μm data and fluxes from the literature, we find that the 450/850-μm flux ratio for the galaxies is remarkably constant, and this holds from objects in which the star formation rate is similar to our own Galaxy, to ultraluminous infrared galaxies (ULIRGs) such as Arp 220. The only possible explanation for this is if the dust emissivity index for all of the galaxies is ∼2 and the cold dust component has a similar temperature in all galaxies . The 60-μm luminosities of the galaxies were found to depend on both the dust mass and the relative amount of energy in the warm component, with a tendency for the temperature effects to dominate at the highest L 60 . The dust masses estimated using the new temperatures are higher by a factor of ∼2 than those determined previously using a single temperature. This brings the gas-to-dust ratios of the IRAS galaxies into agreement with those of the Milky Way and other spiral galaxies which have been intensively studied in the submm. 相似文献
15.
使用澳大利亚ＡＴ对６个近距中等红外光度的ＩＲＡＳ星系在双频上同时进行了观测．其中ＩＲＡＳ２０２７２－４７３８、ＩＲＡＳ２３１５６－４２３８探测到射电发射．获得了它们的射电流量、峰值位置、源的大小、频谱指数等射电参数,用红外、射电、光学资料对射电源进行了证认．并结合以前的观测资料讨论了这类星系射电发射的特点． 相似文献
16.
Parag Seal 《Astrophysics and Space Science》1985,113(2):391-404
From IRAS (Infrared Astronomical Satellite) Circulars Nos. 4 to 15, 110 infrared sources have been identified. Out of these 110 identified sources 99 are galaxies, nine are nebulae, one is a dark object, and one is a non-stellar object. Thirty-five of these galaxies, have already been studied, mostly are spiral type. The characteristics of sixty-four remaining galaxies, for which the type is not known or uncertain, are studied by compairing their colours and luminosities with known galaxies. The galaxies observed by IRAS are mostly active galaxies. 相似文献
17.
The properties of OH megamaser galaxies in the x-ray region are discussed. Observational data from the XMM-Newton x-ray satellite
are presented for three megamasers, IRAS 01418+1651, IRAS 11010+4107, and IRAS 13218+0552. Based on a sample of OH megamaser
galaxies it is shown that the x-ray and OH emission are closely coupled. Megamaser emission also correlates with the column
density of the medium and the OH emissivity increases as the square of the column density. The results of this study indicate
that in OH megamaser galaxies an active nucleus, x-ray heating of molecules, and saturation of the maser emission can play
an important role. In some megamasers, active star formation may be the dominant source.
__________
Translated from Astrofizika, Vol. 50, No. 2, pp. 171–182 (May 2007). 相似文献
18.
本文发表的是用北京天文台60厘米施密特望远镜进行发射线星系物端棱镜巡天结果的第四篇文章。文中的表1包括100个发射线天体,其中的96个是发射线星系;其余的对象有3个行星状星云,1个发射线星。在这些发射线星系中,属于s,sd型的有69个,d,ds型的有27个,分别占72％和28％。除了4个已知的Seyfert星系之外,至少还有5个也可能是Seyfert星系。这些发射线天体中的23个是IRAS源,它们都与具有强发射的现象相联系. 相似文献
19.
By use of the ANS ultraviolet fluxes, optical (UBV) and IRAS infrared fluxes, several colour indices for a few Markarian galaxies have been investigated. A comparison of these indices with those for normal NGC galaxies has been carried out. Similarities and differences in the indices for the two groups of galaxies have been discussed and possible causes have been indicated. 相似文献
20.
《New Astronomy Reviews》2000,44(7-9):539-541
We present the first results of a search for the presence of rapid optical variability in a sample of five Narrow-Line Seyfert 1 galaxies. We find clear evidence of rapid variability for IRAS 13224-3809 with variations occurring on time scales of an hour. However, the results are less conclusive for the other four sources in our sample, Markarian 766, PG 1244+026, PG 1404+226 and Arakelian 564. While there are several instances among these latter objects where there is a hint that variability may be present, IRAS 13224-3809 provides the only conclusive evidence of rapid optical variability detected to date. 相似文献