Far-infrared and molecular line observations of Lynds 183 - Studies of cold gas and dust
Far-infrared and molecular line observations of Lynds 183 - Studies of cold gas and dust
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Lynds 183 的远红外和分子线观测 - 冷气体和尘埃的研究
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发表时间：
2001
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通讯作者：
T. Prusti
中科院分区：
文献类型：
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作者：
M. Juvela;K. Mattila;K. Lehtinen;D. Lemke;R. Laureijs;T. Prusti
我们用ISO卫星上的ISOPHOT光度计在100米和200米的远红外波段上绘制了L183暗云的图。这些观测结果首次使我们有可能研究L183中大尘埃颗粒的分布和性质，而不会与小颗粒相混淆。观测结果表明，色温的变化很可能是由尘埃粒子的发射特性变化引起的。在云核中，远红外线的色温降到12 K以下。这些数据允许一个新的确定云的质量和质量分布的基础上粉尘排放。距云中心10 0半径范围内的质量估计为25 M。我们绘制了包括DCO+（2{1）和H13 CO+（1{0）在内的几条分子谱线的云图.这些物质被认为是冷而致密分子物质的示踪剂，我们检测到DCO+发射与尘埃色温之间存在强烈的反相关性。特别地，在色温上升到15 K以上的100 m发射的最大值附近没有检测到DCO+（2{1}）发射。H13 CO+的发射与DCO+的分布密切相关，但CO同位素在100 m处也有较强的发射。DCO+和C 18 O图的详细比较显示了物种相对强度的急剧变化。从形态学上看，200米的尘埃排放追踪了致密分子材料的分布，例如在C 18 O线中看到的。然而，与尘埃柱密度的比较表明，在云核中，C18 O的贫化系数为1.5。本文给出了R-A ndB带星计数的结果。灭绝与200公吨的甲烷和100公吨的甲烷排放有更好的相关性。根据200米的相关性在低消光值，我们推导出一个值为17米的视觉消光对云中心，没有背景恒星观察了。
We have mapped the dark cloud L183 in the far-infrared at 100 m and 200 m with the ISOPHOT photometer aboard the ISO satellite. The observations make it possible for the rst time to study the distribution and properties of the large dust grains in L183 without confusion from smaller grains. The observations show clear colour temperature variations which are likely to be caused by changes in the emission properties of the dust particles. In the cloud core the far-infrared colour temperature drops below 12 K. The data allow a new determination of the cloud mass and the mass distribution based on dust emission. The estimated mass within ar adius of 10 0 from the cloud centre is 25M. We have mapped the cloud in several molecular lines including DCO+(2{1) and H 13 CO+(1{0). These species are believed to be tracers of cold and dense molecular material and we detect a strong anticorrelation between the DCO+ emission and the dust colour temperatures. In particular, the DCO+(2{1) emission is not detected towards the maximum of the 100 m emission where the colour temperature rises above 15 K. The H 13 CO+ emission follows closely the DCO+ distribution but CO isotopes show strong emission even towards the 100m peak. Detailed comparison of the DCO+ and C 18 O maps shows sharp variations in the relative intensities of the species. Morphologically the 200 m dust emission traces the distribution of dense molecular material as seen e.g. in C 18 O lines. A comparison with dust column density shows, however, that C 18 O is depleted by a factor of1.5 in the cloud core. We present results of R -a ndB-band starcounts. The extinction is much better correlated with the 200 mt han with the 100m emission. Based on the 200m correlation at low extinction values we deduce a value of 17 m for the visual extinction towards the cloud centre where no background stars are observed anymore.