【摘 要】
:
We present a statistical analysis of 482 6.7 GHz methanol maser sourcesfrom the available literature, on their maser emission and the characteristics oftheir as
【机 构】
:
National Astronomical Observatories,Shanghai Astronomical Observatory,Department of Astronomy
论文部分内容阅读
We present a statistical analysis of 482 6.7 GHz methanol maser sourcesfrom the available literature, on their maser emission and the characteristics oftheir associated infrared sources. On the color-color diagram, more than 70% ofthe objects fall within a very small region (0.57 ≤ [25 - 12] ≤ 1.30 and 1.30 ≤[60 - 12] ≤ 2.50). This suggests that 6.7 GHz methanol maser emission occurs onlywithin a very short evolutionary phase during the earliest stage of star formation.The velocity ranges of the masers belong to two main groups: one from 1 to 10km s-1, and one from about 11 to 20 km s-1. These velocity ranges indicate thatthe masers are probably associated with both disks and outflows. The correlationsbetween the maser and infrared flux densities, and between the maser and infraredluminosities, suggest that far-infrared radiation is a possible pumping mechanismfor the masers which most probably originate from some outer molecular envelopesor disks.
其他文献
Consider a backward heat equation in a bounded domain Ω R2 with the noisy data in theinitial time geometry. The aim is to find the temperature for 0 <ε< t < T. F
The chemical structure of an exopolysaecharide (EPS) produced by Sorangium cellulosum NUST06 was investigated. The EPS was found to have molecular masses greate
This paper reports the electrochemical properties of sulpiride at a mercury electrode, especially its adsorptive characteristic. Sulpiride dissolved in a suppor
In order to predict the influence of operating temperature on cyclone performance, an experimental investigation on particle separation was conducted in a 300 m
A constitutive model of quasi-Newtonian fluid based on the type of flow is used in abrupt planar contraction flow.The numerical results from finite element anal
The author studies minimal surfaces in 3-dimensional solvable Lie groups with left invariantRiemannian metrics. A Weierstraβ type integral representation formu
The polymerization of amphiphilic self-assemblies is a promising method to synthesize nano-structured materials with novel properties. These materials have many
Sequence comparison leads to a combinatorial optimization problem of sorting permutations by reversals and transpositions. Namely, given any two permutations, f
The correlation between shape and size of linear chains on the simple cubic lattice is investigated using a dynamic Monte Carlo technique. A positive correlatio
利用凝胶排阻层析-火焰原子吸收光谱法研究了Ag+在照相明胶中分子量的分布情况.研究表明,利用葡聚糖凝胶G-75可有效的将明胶中的γ、β、α及小分子蛋白L组分分开.发现Ag+完