摘要
利用毫米波射电天文所(Institut de Radioastronomie Millimétrique,IRAM)30 m射电望远镜在1.3–4.0 mm波段的分子谱线成图,结合70–870μm连续谱数据以及绿岸射电望远镜(Green Bank Telescope,GBT)对NH_(3)(J,K)=(1,1)和(2,2)谱线的成图(J为总角动量量子数,而K描述角动量在分子主轴方向的分量),对G 011.0970-0.1093纤维状分子云末端的一对比邻云团进行了观测.尽管在870μm波段下它们都表现出与连续谱流量峰值成协,但在70μm波段下,它们呈现出明亮与暗弱的对照特性.对这两个云团进行对比分析发现:(1)该极早期大质量恒星形成区的气体尘埃温度高度耦合;(2)70μm明亮云团的气体尘埃温度从中心(约17 K)到包层边缘呈递减趋势,这预示着云团内部可能已经有原恒星形成;70μm暗弱云团中心较边缘更冷(约11K)更致密(约5×10^(22)cm^(-2)),且氢分子柱密度与尘埃温度存在强反相关,故外部辐射可能主导该云团加热;(3)在pc尺度上,气态C^(18)O的耗损率f_(D)(C^(18)O)与HCO^(+)的氘化率存在强正相关,且气态C^(18)O在冷且致密的DCO^(+)主导云团耗损f_(D)(C^(18)O)高达7;(4)在气体尘埃温度从10 K到20 K,氢分子柱密度从10^(22)cm^(-2)到10^(23)cm^(-2)的变化环境里,HCO^(+)、N_(2)H^(+)、HNC在更.为致密冷暗的环境氘化率增丰明显,HCN则在稍温暖且70μm明亮的环境氘化率增丰更大,而NH3氘化率在此环境中没有明显变化.这些不同分子氘化增丰的差异性可能源自其气体尘埃反应路径的差异性.
Using the IRAM(Institut de Radioastronomie Millimetrique)30 m for a molecular line imaging survey at 13-4.0 mm,in conjuntion with archival dust contiunuum images spanning 70-870 pum,and NH_(3)(J,K)=(1,1)and(2,2)images from GBT(Green Bank Telescope),a pair of neighboring clumps within the tail of filamentary molecular cloud G 0110970-0.1093 is studied.While both clumps coincide spatially with the dust continuum emission peak at 870μm,they exhibit contrasting brightnesses at 70μm.Comparative analysis of these two clumps reveals:(1)The gas and dust temperatures are tightly coupled within this extremely youhg high-mass star-forming region.(2)Gas-dust temperatures of the 70 um bright clump decrease from the center(~17 K)to the envelope edge,suggesting the initiation of protostellar activities within the clump;conversely,the central region of the 70 pum dark cloud clump is colder(~11 K)and denser(~5×10^(22)cm^(-2))compared to its periphery,with a strong anti-correlation between the H2 column density and dust temperature pixel by pixel,indicating dominant external heating shaping the temperature profle of this clump.(3)A strong positive correlation exists between the gaseous C^(18)O depletion(f_(D)(C^(18)O))and the deuterium fraction of HCO^(+)at pc scales,with f_(D)(C^(18)O)reaching up to 7 in the cold and dense DCO^(+)dominated region.(4)With gas-dust temperatures ranging from 10 K to 20 K and Hq column densities ranging from 10^(22)cm^(-2)to 10^(23)cm^(-2),HCO^(+),N_(2)H^(+),and HNC exhibit significant deuteration enhancements towards the colder and denser clump,while HCN shows greater deuteration enhancement in slightly warmer and 70 pum brighter clumps,and NHz deuteration shows no significant change.These deuteration differentiation among species are likely related to their gas-dust forming pathways.
作者
师昆鹏
冯思轶
林淑婷
高乐涵
SHI Kun-peng;FENG Si-yi;LIN Shu-ting;GAO Le-han(Department of Astronomy,College of Physical Science and Technology,Xiamen University,Xiamen 361005)
出处
《天文学报》
北大核心
2025年第3期13-29,共17页
Acta Astronomica Sinica
基金
国家自然科学基金项目(12373023)
厦门大学校长基金项目(20720220024)资助。
