共查询到19条相似文献，搜索用时 140 毫秒
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利用青海站的13.7米射电望远镜对河内24个与水脉泽源成协并有红外Spitzer数据的巨分子云核进行12CO(J=1→0),13CO(J=1→0)和C18O(J=1→0)的同时成图观测,平均的成图范围为81×81.并全部探测到了C18O的谱线发射,其中11个源有较大范围(51-81)的C18O成图,这些分子云核均观测到C18O(J=1→0)谱线积分强度极大值的一半处,其余的13个源由于信噪比低或者成图范围较大等原因,没有进行如此大面积的成图观测.对样本中的11个已成图的稠密核进行了云核特性的分析并统计比较了CO与13CO,13CO与C18O及CO与C18O谱线积分强度之比(R12/13,R12/13,R12/18),结果是,C18O是光学薄的,可以探测到云核更加细致的结构.从核中心到边缘,3种谱线积分强度比是逐渐增加的.CO与13CO的谱线积分强度比R12/13的范围在2-6之间;13CO与C18O的比值R13/18范围在4-20之间波动,中心区域其值大部分集中在6-12之间,变化范围波动不是很大;CO与C18O之比R12/18在13-90更大的范围内,在更加致密的云核中心该比值集中在13-50之间. 相似文献
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利用青海站13.7 m毫米波望远镜对17个与星团成协的恒星形成区进行了~(12)CO(J=1-0)、~(13)CO(J=1-0)和C~(18)O(J=1-0)的同时成图观测.除了IRAS04547+4753,这些源均探测到较强的C~(18)O(J=1-0)的谱线发射.由于分子云的大小不同,有13个源观测到~(13)CO(J=1-0)谱线积分强度极大值的一半处,其他源因分子云延展范围较大,没有进行大面积的成图观测.基于观测数据,计算了各云核的谱线线宽、亮温度、尺度、密度和质量等,~(13)CO和C~(13)O云核的维里质量与局部热动平衡(LTE)质量之比分别为0.66和0.74,它们接近于维里平衡状态.为了从形态方面比较云核与星团,将谱线的积分强度图与2MASS的K波段图像叠加.同时,计算了与云核成协的星团的大小和质量,数据采用了2MASS的近红外点源测光结果.基于云核与星团的质量结果,计算了分子云的恒星形成效率,大致在10%～30%的范围. 相似文献
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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
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本文主要论述用25米射电望远镜和自相关频谱仪于1986年4月13—17日(UT)期间在我国陕西眉县首次对哈雷彗星羟基分子1667 MHz射电话线的观测及归算结果。由谱线轮廓的幅度、宽度、形状和面积相继导出的谱线强度为-2.4Jy,膨胀速度为0.92kms~(-1),速度的一级矩为0.20kms~(-1),以及羟基的母分子产生率为1.7×10~(29)mols~(-1)。文中所给出的宇宙羟基源W3和W12的观测结果,分别用来检验设备系统探测射电谱线的功能及对哈雷彗星的羟基谱线进行强度定标。这些结果均同理论预期或以往的有关观测相符合。 相似文献
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利用紫金山天文台青海观测站13.7 m毫米波望远镜对IRAS 23133 6050云核进行~(13)CO、C~(18)O、HCO (J=1-0)谱线观测.~(13)CO、C~(18)O、HCO 分子谱线辐射所对应的云核直径分别为4.0pc、2.1 pc、2.3 pc,质量分别为2.7×10~3M_⊙、0.9×10~3M_⊙、2.3×10~3M_⊙,气体平均密度分别为2.7×10~3 cm~(-3)、5.1×10~3 cm~(-3)、4.6×10~3cm~(-3).用幂律模型n(r)～~(-P)的形式分析了云核的密度分布,得到的指数p分别为1.75、1.56、1.48.分析发现,密度结构谱指数从云核的外部向内部逐渐变平坦.观测得到HCO~ 丰度为4.6×10~(-10),比暗云低一个数量级以上,比巨分子云也略低,而~(13)CO、C~(18)O的相对丰度比X_(13/18)为12.2,这与暗云11.8和巨分子云9.0～15.6的情况一致.该区域发现存在~(13)CO双极外流.由IRAS远红外光度和维里质量得到的光度质量比,分别为18.1,51.1、21.2. 相似文献
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本文作者首次对暗云Ｌ１２１１的Ｃ~（１８）Ｏ（Ｊ＝１－０）分子发射谱线进行了观测，发现了暗云Ｌ１２１１致密核的Ｃ~（１８）Ｏ（Ｊ＝１－０）的宽翼发射谱线和它的结构，得到了核区Ｃ~（１８）Ｏ（Ｊ＝１－０）分子的谱线轮廓图、强度分布图、速度分段积分等高图、速度位置图。 相似文献
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对MSX红外暗云G79.2+0.38的11'×7'的区域范围进行了12CO(1-0)、13CO(1-0)和C18O(1-0)谱线的同时观测.观测到的两个C18O(1-0)谱线所界定的云核峰值分布分别对应MSX A波段的两块高消光区域.该区域的氢分子柱密度N(H2)-(5-12)×1022 cm-2,平均密度n-(3±1)×104cm-3.两块分子云核的13CO的线尺度分别是1.7和1.2 pc,而C18O的线尺度分别是1.2和0.6 pc,它们包含的质量为2×102-2×103M(?).分子云核的视向平均密度结构可用幂函数(?)(p)-p-0.34±0.02表征. 13CO和C18O的丰度和典型的光学暗云相比低了4至11倍,但是目前还没有证据表明13CO和C18O的相对丰度比X13/18随柱密度有显著变化. 相似文献
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暗云L1211的C^18O（J=1—0）分子发射谱线的观测 总被引：1，自引：1，他引：0
本文作者首次对暗云Ｌ１２１１的Ｃ＾１８Ｏ（Ｊ＝１－０）分子发射谱线进行了观测，发现了暗云Ｌ１２１１致密核的Ｃ＾１８Ｏ（Ｊ＝１－０）的宽翼发射谱线和它的结构，得到了核区Ｃ＾１８Ｏ（Ｊ＝１－０）分子的谱线轮廓图、强度分布图、速度分段积分等高图、速度位置图。 相似文献
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We present results of 13CO(1-0),C18O(1-0),and HCO+(1-0) map observations and N2H+(1-0) single point observations directed towards a sample of nine low-luminosity 6.7-GHz masers.N2H + line emission has been detected from six out of nine sources,C18O line emission has been detected from eight out of nine sources,and HCO + and 13CO emission has been detected in all sources.In particular,a blue profile of the HCO + spectrum,a signature of inflow,is found towards one source.From integrated intensity emission map... 相似文献
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从在CepheusE中C18O（J＝1－0）的谱线频谱图发现,相对于峰速度的蓝移成分的积分流量密度明显大于相对于红移成分的积分流量密度．从在它的强度分布图也可以发现强度分布轮廓向西北和向东延伸．为此,研究了在CepheusE中C18O（J＝1－0）的速度分段积分等高图,发现相对于峰速度的蓝移速度分段积分等高图中的C18O（J＝1－0）的积分强度,要大于相对于红移速度分段积分等高图中的C18O（J＝1－0）的积分强度,同时强度分布图中的分子外流的不准直分布是由相对于峰速度的蓝移成分的分布的不准直性所引起的． 相似文献
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利用紫金山天文台青海站的13．7m毫米波望远镜,对NGC1333／IRAS6－9附近的一个10．3'X10'和6．8'X8'的恒星形成区,进行了13CO（1－0）和C18O（1－0）的成图观测,发现了多个新的分子云核和沿SSV12－IRASS方向的13CO（1－O）双极外向流．本文给出了每个云核的观测特性和物理参数．分析了这一区域的云核分布和速度场结构．详细讨论了该区域的云核分布、双极外向流和群集的年轻天体、红外源以及HH天体的关系． 相似文献
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Xin-Jie Mao Xiao-Xia Sun Department of Astronomy Beijing Normal University Beijing maoxj@bnu.edu.cn 《中国天文和天体物理学报》2005,5(2):144-150
We map the dark molecular cloud core of L134 in the C18O (J = 1 - 0) emission line using the PMO 13.7m telescope, and present a contour map of integrated intensity of C18O (J = 1 - 0) emission. The C18O cloud is inside the distribution of extinction AB, the visual extinction of blue light, as well as inside the 13CO cloud in the L134 region. The depletion factors in this C18O cloud are generally greater than unity, which means there is gas depletion onto dust. Since only a minimum AB = 9.7 mag is available, and our observations measure both undepleted and depleted regions along the line of sight, the depletion factors could very likely be larger in the central core than the calculated value. So we conclude that depletion does occur in the bulk of the C18O cloud through a comparison between the C18O and blue extinction maps in the L134 region. There is no direct evidence as yet for star formation in L134, and so cores on the verge of collapse will not be visible in CO and other gas molecules. 相似文献
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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
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Jarken Esimbek 《中国天文和天体物理学报》2005,5(4):363-370
The excitation of H2O masers usually needs very high density gas, hence it can serve as a marker of dense gas in HII region. We selected a sample of H2O maser sources from Plume et al. (four with, and four without detected CS(J = 7-6) emission), and observed them in 13CO(J=1-0) and C18O (J=1-0). C18O (J=1-0) emission was detected only in three of the sources with detected CS(J=7-6) emission. An analysis combined with some data in the literature suggests that these dense cores may be located at different evolutionary stages. Multi-line observation study may provide us clues on the evolution of massive star forming regions and the massive stars themselves. 相似文献
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利用日本名古屋大学天体物理系的毫米波射电望远镜对CepheusC的C18O（J＝1－0）分子辐射首次进行了观测，得到了强度分布图．从强度分布图上，我们发现C18O（J＝1－0）分子的分布呈现三个核．通过计算得到了三个核的物理参数． 相似文献
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With the 13.7 m millimeter wave telescope of Purple Mountain Observatory at Qinghai Station, the simultaneous mapping observations at the 12CO(J=1-0), 13CO(J=1-0) and C18O(J=1-0) lines were performed towards the 24 Galactic high-mass star-forming cores, which are associated with water masers and have available Spitzer's infrared data. The average mapping range was 8′ × 8′. The C18O line emission was detected in all the cores, in which 11 cores were observed to the half maximum of their C18O integrated intensities and the rather extended (5′ − 8′) C18O maps were obtained, while the others were failed to make such a large scale mapping because of the low SNR or the intrinsically extended morphology of the cores. On the 11 completely mapped dense cores, we analyzed their characteristics and made the statistics and comparisons on the integrated intensity ratios between 12CO and 13CO (R12/13), 13CO and C18O(R13/18), as well as 12CO and C18O(R12/18). We concluded that as a tracer of dense gas, C18O is absolutely optically thin and can be used to detect the detailed structures of the cores, and that in general the 3 ratios increase gradually from the core center to the periphery. We found that the integrated intensity ratio R12/13 ranges from 2 to 6; R13/18 fluctuates between 4 and 20, but in central regions it is concentrated in the range 6–12 with a small fluctuation; and R12/18 occupies a wider range 13–90, but it is concentrated between 13 and 50 in the denser regions of the cores. 相似文献
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We have obtained velocity-resolved spectra of the 12C II 157.8 microns 2P3/2-2P1/2 fine structure line in the M42 region of Orion. Observations at 0.8 km s-1 resolution with a laser heterodyne spectrometer show multiple velocity components in some locations, with typical linewidths of 3-5 km s-1. Spectra of theta 1C and BN-KL also show weak emission from the F = 2-1 hyperfine component of the equivalent 13C II line. From the observed 12C II/13C II line intensity ratios, we deduce that the 12C II emission is optically thick with tau approximately 5 at both positions. Excitation temperatures of 128 K and 90 K, together with column densities of approximately 1 x 10(19) cm-2 and approximately 4 x 10(18) cm-2, are derived for theta 1C and BN-KL, respectively. 相似文献