共查询到20条相似文献，搜索用时 31 毫秒
1.
一、引言1924年,蔡伯(H.Von Zeipel)提出了一条著名的定理:一个处于流体静力学平衡和辐射平衡的自转星,通过水准面上一面元的总辐射流和该面元处的有效重力成正比.因而,自转星表面的亮度随着纬度的不同而不同,两极区域此赤道区域亮一些,这被称为“重力昏暗”效应.后来,在计算快速自转恒星受自转畸变了的谱线的理论轮廓以及研究密近交食双星的光变时,基于蔡伯定理的重力昏暗得到了应用. 相似文献
2.
The data of the line series CH3CN 8(K) – 7(K) K = 0 – 7 and line CS J = 3 – 2 were taken simultaneously. At beam size of 16 the emissions of CH3CN and CS have a common center position located near IRc2 with deviations -8 and 5. The observed data show that in Orion KL core the integrated intensities of the two species have double peaks separated by a space of 14. The 2-dimension Gaussian fitting plots (FWHM) are ellipses ofD
maj = 26 andD
min = 22 for CH3CN 8(K) – 7(K) K = 3 – 6 andDmaj = 39 Dmin = 31 for CS J = 3 – 2 at a distance about 450 pc. Towards the multiple line emission region of CH3CN 8(K) – 7(K) K = 3 – 6, using a simplified very large velocity gradient model to solve the statistical equilibrium and radiative transfer equations, we find to fit the observed results, the optimum physical parameters and kinetic temperatureT
k 120 K, densityn(H
a) 1.2 × 105 cm–3, velocity gradientV
gr 92 km s–1 pc–1 and the local abundance of CH3CNF
ab 3 × 10–8. However towards the region of single line emission of CS J = 3 – 2 we have to use LTE and the optical thin approximation on the assumption ofT
k= 120 K to obtain the lower limits of column density and then, an averaged abundance of CS of 6 × 10–8. 相似文献
3.
《天文和天体物理学研究(英文版)》2020,(9)
Data of ~(12)CO/~(13)CO/C180 J=1→0 emission toward the Galactic plane region of l=35° to 450 and b=-5° to+ 5° are available with the Milky Way Imaging Scroll Painting(MWISP) project.Using the data,we found a giant molecular filament(GMF) around l≈38°~42°,b≈-3.5°~0°,V_(LSR)≈27~40 km s~(-1),named the GMF MWISP G041-01.At a distance of 1.7 kpc,the GMF is about 160 pc long.With a median excitation temperature about 7.5 K and a median column density about10~(21) cm~(-2),this GMF is very cold and very diffuse compared to known GMFs.Using the morphology in the data cube,the GMF is divided into four components among which three show filamentary structure.Masses of the components are 10~3~10~4 M_☉,with a total mass for the whole filament being about 7×10~4 M_☉from the local thermodynamic equilibrium method.~(13)CO cores inside each component are searched.Virial parameters are about 2.5 for these cores and have a power-law index of -0.34 against the mass.The mass fraction of dense cores traced by ~(13)CO to the diffuse clouds traced by ~(12)CO is about 7% for all components of the GMF.We found signatures of possible large scale filament-filament collision in the GMF. 相似文献
4.
R. J. Dodd 《Astrophysics and Space Science》1976,44(1):85-99
Star counts, from measurements made by the GALAXY measuring machine, in unit B magnitude intervals were made in nine regions, each of 1.75 square degrees distributed about (l, b)= (140°, 0°). The mean density function and the mean variation of interstellar absorption with distance for the various areas were determined using a combination of theoretical and observed cumulative Wolf diagrams. For the same regions multi-colour (UBV) photographic photometry was used to identify early type stars. The distribution of these stars shows three main peaks which correspond well in distance with the Perseus, - and -spiral arms found by Verschuur from radio measurements of neutral hydrogen. The pattern made by the stellar arms in the (l, r) plane shows a discontinuity nearl=140°. From a consideration of both the star counts and the distribution of the reddened early type stars it is suggested that the cause of the discontinuity is a cloud with 0
.
m
7 total obscuration situated much nearer to the Sun than the Perseus arm and terminating on one side atl=140°. 相似文献
5.
本文作者用北京天文台兴隆站２．１６米望远镜及卡焦ＣＣＤ摄谱仪，观测到一颗红移为１．６６的类星体，讨论了该望远镜卡焦摄谱系统的总体光效率。 相似文献
6.
S. Selak 《Astrophysics and Space Science》1989,159(1):153-156
In this Letter we propose to consider the four-energy-space whose coordinates are composed as follows: (i) the coordinate 0 refers to the internal energy of the body (it is involved as an unknown function of the rest-energy and the kinetic energy of the body), and (ii) the coordinates 1, 2, 3 relate to the presence of gravitational, electromagnetic, and thermal energy at the location of the body respectively. We involve yet the proper energy interval d2 by analogy to the four-interval ds
2 in general relativity. From such metric field we calculate the Ricci tensor in the simplest case. In addition, we require its form to be the same one as that considered by Schwarzschild. Comparing both solutions we obtain Einstein's relationE=mc
2. 相似文献
7.
若干恒星形成区的^12CO（J=1—0）与^13CO（J=1—0）观测 总被引：1，自引：0，他引：1
首次利用紫金山天文台青海观测站13.7m毫米波射电望远镜对若干分子云与恒星形成区的~(12)CO(J=1—0)和~(13)CO(J=1—0)分子辐射进行了观测,得到了各自中心位置的谱线轮廓。作为一个实例本文将介绍如何通过对分子云~(12)CO(J=1—0)和~(13)CO(J=1—0)谱线的综合分析与计算得到云中的物理参数。 相似文献
8.
S. Al-Mufti A. H. Olavesen F. Hoyle N. C. Wickramasinghe 《Astrophysics and Space Science》1982,84(1):259-261
Unidentified interstellar absorption bands at =3.2 m and 3.3 m might be due to amino-acids in bacterial grains. 相似文献
9.
为了研究有大质量恒星形成的分子云与其它分子云之间的差异,对北天的59个作为大质量恒星形成区的Spitzer延展绿色天体(Extended Green Objects,简称EGOs)视线方向进行了分子云~(12)CO J=2-1和J=3-2频谱观测,并与文献中对同一批天体方向观测得到的~(12)CO J=1-0频谱数据合并进行分析.对与EGO天体成协的分子云(简称EGO分子云)和其它non-EGO分子云进行了CO多跃迁谱线强度和宽度的统计比较分析.在数据统计的基础上,讨论了这两类分子云的气体温度分布、密度分布、速度场分布对观测数据统计特征的影响.分析结果表明,直接决定是否有大质量恒星形成的关键因素可能并不是巨分子云的质量是否足够大,而是巨分子云的引力塌缩程度足否充分(即分子云团块的体积填充因子是否足够大). 相似文献
10.
使用青海站１３．７米射电望远镜对该望远镜发现的新的水脉泽源进行ＣＯ（Ｊ＝１－０）的观测。本文给出了其中尚未在文献中报道过ＣＯ观测结果的８个源的ＣＯ（Ｊ＝１－０）谱线，并对该观测结果进行了讨论。 相似文献
11.
利用日本名古层大学天体物理系的毫米波电远镜对ＣｅｐｈｅｕｓＡ的Ｃ１８Ｏ（Ｊ＝１－０）分子辐射进行了观测。得到了它的谱线频谱图，强度分布图，速度分段积分等高图和位置速度图，并且得最核区的有关参数。 相似文献
12.
13.
We present new radio observations of molecular lines in the region of high mass star formation, namely G122.0-7.1. A large-scale
map of the emission observed in the 12CO (J = 1−0) and 13CO (J = 1−0) lines covers the area of 15′ × 9′, revealing two dense regions. The molecular bipolar outflows have been resolved
in ASO1 region. It is associated with the known candidate YSO nearby IRAS 0042 + 5530. Also, a new dense region has been discovered
in the North-Western part of the G122.0-7.1 at a distance of 5′ from IRAS 0042 + 5530. Its position is close to the peak of
4850 MHz emission.
The text was submitted by the authors in English. 相似文献
14.
The next list of spectral data on blue stellar objects (BSOs) is presented. 58 FBS objects in a zone with a central declination
δ = + 35° were observed with the 2.6-m telescope at the Byurakan Observatory during 1990–1991. In addition, 3 objects were
observed (3 CCD spectra were obtained) with the BAO 2.6-m and OHP 1.93-m telescopes in 1997–2000 using modern instrumentation.
9 white dwarfs, 47 hot subdwarfs, and 2 HBB stars have been discovered. Spectra of the 10 most interesting objects are given.
__________
Translated from Astrofizika, Vol. 51, No. 2, pp. 277–283 (May 2008). 相似文献
15.
Tsutomu Takashima 《Astrophysics and Space Science》1976,43(1):213-232
The diffuse radiation in the upward direction at the top and at an internal level of an inhomogeneous atmosphere is computed at =0.40 m. The surface is assumed to reflect light in accordance with a hybrid mode of a diffuse and specular reflector. The objective is to estimate the effect of underlying surface characteristics in terms of the diffuse radiation field. By making use of these results, accuracy in monitoring the atmospheric aerosols would be increased for the use of remote sensing satellite techniques. Junge power lawv
*=3 is adopted for the size distribution of aerosols (1963), while the data given by McClatchyet al. (1971) is used for the number density of aerosols with height distribution. It is noted from the computations that the diffuse reflection radiation is affected by the surface characteristics, even if the albedo of the surface is a fixed constant and very small.On leave from the Meterological Research Institute, Tokyo, Japan.bl]References 相似文献
16.
17.
18.
This paper deals with molecular clouds discovered in the absorption spectra (z=2–3) of distant quasars. It is argued that these clouds belong to the gaseous subsystems of young galaxies. We estimate the gas concentration to ben<104 cm–3 in the cloud observed in the direction of the quasar PHL957. It is shown that this cloud is exposed to ultraviolet radiation. The UV-energy flux does not exceed the value typical for our Galaxy by an order of magnitude (F2×10–6 ergs cm–2 s–1 Å–1 at =2000 Å). The mechanisms maintaining the thermal balance in this cloud are discussed. 相似文献
19.
K. C. Howell 《Celestial Mechanics and Dynamical Astronomy》1987,40(3-4):393-407
A timing condition for consecutive collision orbits in the planar, circular three-body problem has been extended to the elliptic restricted problem for =0. The expression developed relates eccentric anomalies at the time of collision. Some families of solutions are presented. 相似文献
20.
Jun Ma ;Richard de Grijs ;Zhou Fan ;Soo-Chang Rey ;Zhen-Yu Wu ;Xu Zhou ;Jiang-Hua Wu ;Zhao-Ji Jiang ;Jian-Sheng Chen ;Kyungsook Lee ;Sangmo Tony Sohn 《天体物理学报》2009,(6):641-652
Mayall Ⅱ = G1 is one of the most luminous globular clusters （GCs） in M31. Here, we determine its age and mass by comparing multicolor photometry with theoretical stellar population synthesis models. Based on far- and near-ultraviolet GALEX photometry, broad-band UBVRI, and infrared JHKs 2MASS data, we construct the most extensive spectral energy distribution of G 1 to date, spanning the wavelength range from 1538 to 20 000A. A quantitative comparison with a variety of simple stellar population （SSP） models yields a mean age which is consistent with G1 being among the oldest building blocks of M31 and having formed within ～1.7 Gyr after the Big Bang. Irrespective of the SSP model or stellar initial mass function adopted, the resulting mass estimates （of order 10^7M⊙） indicate that GI is one of the most massive GCs in the Local Group. However, we speculate that the cluster＇s exceptionally high mass suggests that it may not be a genuine GC. Our results also suggest that G1 may contain, on average, （1.65±0.63） × 10^2L⊙ far-ultraviolet-bright, hot, extreme horizontal-branch stars, depending on the adopted SSP model. In addition, we demonstrate that extensive multi-passband photometry coupled with SSP analysis enables one to obtain age estimates for old SSPs that have similar accuracies as those from integrated spectroscopy or resolved stellar photometry, provided that some of the free parameters can be constrained independently. 相似文献