共查询到19条相似文献,搜索用时 62 毫秒
1.
一个小质量恒星形成区的物理和动力学性质 总被引:1,自引:0,他引:1
利用VLA的观测,我们在猎户座分子云区,发现了11个小质量分子云浓度核。它们的平均有效半径为0.03pc,平均质量为3.5M⊙,分布在呈丝状母云南北走向的轴线上,在浓核区3'的范围内,测到有5kms^-1pc^-1的速度梯度。一个可能的解释是这个核区的慢速转旋。根据我们的NH3(1,1)的观测资料,并与尘埃的毫米波连续辐射和红外辐射比较,我们认为这个区域的大部浓核是还没有星核的年轻分子云核,正处于 相似文献
2.
恒星形成于分子云之中, 分子外向流是恒星形成正在进行的重要动力学特征, 也是研究和认识恒星形成的重要契入点. 利用紫金山天文台青海观测站德令哈13.7m毫米波望远镜, 采用5种分子谱线探针(包括12CO、13CO、C18O、HCO$^+$ $J=1-0$和CS $J=2-1$, J为角动量量子数), 对一个包含IRAS 19230+1506、IRAS 19232+1504和G050.3179--00.4186这3个源的大质量恒星形成复合体进行了成图观测研究. 通过对以上分子谱线数据并结合红外波段巡天数据的分析, 在这3个源中首次探测到了分子外向流活动, 并确定了分子外向流的中心驱动源. 最后对这3个源进行了分子外向流相关物理量参数的计算, 分析了这些物理量参数之间的关系, 结果表明分子外向流的性质与中心驱动源的性质息息相关. 相似文献
3.
利用均匀磁化球模型,对OrionB云中的39个分子云浓核,从它们观测的源半径和分子线线宽,推求它们的数密度和磁场,得到平均磁场110μG,平均密度为8×10^4/cm^3,这些计算值与观测结果一致,对于R〉0.2pc的分子云浓核,利用均匀磁化球模型推求磁场和数密度的方法是一种可行的方法。 相似文献
4.
分子云核与恒星形成区的良好探针—CH3CN 总被引:2,自引:0,他引:2
本文作者通过对猪户座KL区的观测、分析与计算,阐明CH3CN分子转动谱线系作为分子云核与恒星形成区探讨针的可能性和优越性,并对观测该系所需要的仪器条件进行了讨论。 相似文献
5.
利用紫金山天台青海站的13.7m毫米波望远镜,对OrionA分子云中的OMC-3区域,进行了较高分辨率的^13CO(J=1-0)和C^18O(J=1-0)分子辐射的图观测,给出了该分子云中^13CO和C^18O的云核中心分别与最年龄的天体-Class0类源MMSI,MMS4,MMS6和MMS7,MMS8,MMS9成协,此外,通过分析OMC-3整个区域的速度场结构,发现沿C^18O和^13CO云核 相似文献
6.
本文作者通过对猎户座KL区的观测、分析与计算,阐明CH3CN分子转动谱线系作为分子云核与恒星形成区探针的可能性和优越性.并对观测该线系所需要的仪器条件进行了讨论. 相似文献
7.
罗绍光 《中国天文和天体物理学报》1995,(2)
对恒星形成区CepOB4的IRAS观测结果的详细分析和研究表明,与年轻星团Be59相联系的分子云物质的原始分布是高度成块的。Be59诞生于一个平均密度为100─200cm(-3)云的背向太阳一侧。强烈的电离辐射以及星风已经在其诞生地产生了一个半径大约为5pc的"水泡型(Blister)"电离氢区及与之相关的红外源。电离辐射也穿过云际介质到达与母云分离的另两个云的表面,形成了从侧面看到的电离波前及被压缩和加热的中性物质壳。在这个恒星形成区中,虽然有大量年轻恒星存在,但大质量恒星的形成已经停止。红外发射主要起源于标准尘埃粒子的热平衡发射。但在主激发星团Be59附近的HII区中25μm发射的显著增强可能与某种与电离气体相混合的新型尘埃粒子有关。 相似文献
8.
9.
俞志尧 《中国科学院上海天文台年刊》1997,(18):147-150
利用对暗分子云L1211的C^18O(J=1-0)分子发射谱线的首次观测,计算得到了它的核的物理参数,结果表明间分子云处在维里平衡状态下所得到的核的质量要大于暗分子云处在局部热动平衡状态下所得到的核的质量。同时,暗分子云处在维里平衡状态下所得到的外流力要大于暗分子云处在局部热动平衡状态下所得到的外流力。但是如何恰当地选择N(C^18O)/N(H2)的值,则上述两种质量和两种外流力之间是彼此相互一致的。 相似文献
10.
根据(1)和中图1(a)和图1(b)分别对CepB和CepF进行成图处理,得到了它们的强度分布图和速度分段积分等高图,通过对这些强度分布图和速度分段积分等高图的分析和研究,也得到了CepheusOB3巨分子云复合体是成块的。并且这些块是没有被自引力束缚的,同时还得到了CepB和CepF的外流的动力学时标。 相似文献
11.
Zheng Xing-wu 《Chinese Astronomy and Astrophysics》1995,19(4):459-468
Eleven low-mass cores are found in the Orion Molecular Cloud 2 from VLA observations of the line emission of NH3 (1,1). They are perhaps clumps prior to gravitatonal collapse with average radius of 0.03 pc and mass of 3.5 M, distributed along the central axes of filaments in the NS direction. We find a velocity gradient of 5 km s−1 pc−1 in the declination direction within a 3′ region. Based on our NH3(1,1) observations and compared with dust continuum emission at millimilion wavelength as well as in the infrared, we suggest that most of these dense cores are probably protosteller condensations, not yet containing stellar cores, but are self-gravitating systems in thermodynamical equilibrium. 相似文献
12.
Ralph E. Pudritz 《Astrophysics and Space Science》2002,281(1-2):493-496
We present the results of very high resolution CDM simulations of galaxy formation designed to follow the formation and evolution
of self-gravitating, supergiant star-forming clouds. We find that the mass spectrum of these clouds is identical to that of
globular clusters and GMCs; dN/dM ∝ M
-1.7 ± 0.1.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
13.
Daniele Galli 《Astrophysics and Space Science》2005,295(1-2):43-51
We review the basic theoretical elements leading to our current understanding of the role of magnetic fields in the process of star formation. In particular, we concentrate on: (i) the relevance of the mass-to-flux ratio for the stability of molecular clouds; (ii) the consequences of magnetic flux leakage for the evolution of cloud cores; (iii) the phase of anisotropic dynamical collapse following the formation of strongly peaked density distributions; (iv) the mechanism of magnetic braking as a possible solution to the angular momentum problem in star formation. 相似文献
14.
The dynamics of protostellar envelopes around forming massive stars is analysed and the main stages of the process of massive star formation are identified. It is shown that massive stars can be formed in the outer layers of giant molecular cloud cores. Special conditions are necessary for the formation of massive stars. 相似文献
15.
利用紫金山天文台青海站的 13.7 m毫米波望远镜,对 Orion A分子云中的 OMC-3区域,进行了较高分辨率的13CO(J=1-0)和C18O(J=1-0)分子辐射的成图观测.给出了该分子云中13CO和 C18O云核分布的整体结构和平均物理参数.观测发现,该分子云的13CO和 C18O的云核中心分别与最年轻的天体-Class 0类源 MMSI, MMS4,MMS6和MMS7,MMS8;MMS9成协.此外,通过分析OMC-3整个区域的速度场结构,发现沿 C18O和13CO云核方向从南到北有一个~ 1.7km/s的速度场梯度,而分子云的红、蓝移团块则分别趋于云的北部和南部.并对OMC-3区的恒星形成特征进行了讨论. 相似文献
16.
P. A. Tarakanov 《Astrophysics》2004,47(3):343-351
Observations show that molecular clouds in the interstellar medium are fractals with a dimensionality close to 2.35. A model for the formation of clouds from cloudlets ejected from stars is examined in this paper. It is shown that the motion of cloudlets in the interstellar medium is described by a model of generalized brownian motion, so that the resulting clouds should have a fractal structure. We examine the hypothesis that the fractal dimensionality of a cloud is completely determined by the way the mass of the cloudlets varies. The generalized brownian motion of an ensemble of particles is described as a random process with a time dependent parameter. The relationship among the growth of the cloudlet mass, the properties of the process by which the cloudlets move, and the fractal dimensionality of the structures resulting from this process is examined. It is shown that the fractal dimensionality of the formed clouds corresponds to the natural aggregation of mass assuming random cloudlet collisions. 相似文献
17.
E. V. Volkov 《Astrophysics》2004,47(3):335-342
The limitations imposed by the shear instability on the formation of gigantic molecular clouds in the central regions of spiral galaxies are examined. The criteria obtained here are illustrated using the example of six galaxies for which the detailed rotation curves are known. The different mechanisms for formation of molecular clouds which apply in the central and edge regions of disk galaxies are evaluated. 相似文献
18.
Vladimir Garrido Ortega Gladys Lopes Vieira J.A. de Freitas Pacheco 《Astrophysics and Space Science》1998,262(3):271-295
On the basis of Jeans equations we study some dynamical properties of a sample of E galaxies considered as oblate and prolate spheroids. Although the results emphasize the anisotropy as the dominant dynamical factor both for oblate and prolate configurations, the sample contains some oblate galaxies apparently isotropic consistent with full rotational support. Comparisons of the mass-to-luminosity ratios obtained from our models with ratios derived from recent evolutionary synthesis models do not seem to leave room for nonluminous matter within the ranges (of the order of one de Vaucouleurs' radius) of the kinematical observations. Such comparisons suggest that a flatter than the classical Salpeter IMF would lead to better agreement with the dynamical results obtained within the framework of our models. 相似文献
19.
A. L. Gyulbudaghian 《Astrophysics》2009,52(2):168-183
The hypothesis advanced by V. A. Ambartsumyan according to which stars are formed from prestellar superdense objects-- protostars--
was an alternative to the hypothesis of the 1950's (and even now, not much changed) according to which stars are formed by
accretion with subsequent collapse (in various modifications). Ambartsumyan's basic inferences were based on an analysis of
the observational data available at that time. This paper presents both Ambartsumyan's pioneering ideas and some modern hypotheses
of star formation. Some results from studies of molecular clouds and star formation regions are also discussed. One of the
distinctive features of young stellar objects (YSO) is the outflow of matter from these objects (molecular, in the form of
jets, etc.), a phenomenon whose importance for the evolution of stars was noted by Ambartsumyan as long ago as 1937. Radial
systems of dark globules are examined, as well as H-H objects associated with star formation regions, cometary nebulae, and
close Trapeziumtype systems (consisting of YSO).
Translated from Astrofizika, Vol. 52, No. 2, pp. 185–202 (May 2009). 相似文献