In search of infall motion in molecular clumps Ⅱ:HCO+(1-0)and HCN(1-0)observations toward a sub-samp

来源 :天文和天体物理学研究 | 被引量 : 0次 | 上传用户:jiangyao366
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
Gravitational accretion accumulates the original mass.This process is crucial for us to understand the initial phases of star formation.Using the specific infall profiles in optically thick and thin lines,we searched the clumps with infall motion from the Milky Way Imaging Scroll Painting(MWISP)CO data in previous work.In this study,we selected 133 sources as a sub-sample for further research and identification.The excitation temperatures of these sources are between 7.0 and 38.5 K,while the H2 column densities are between 1021 and 1023 cm-2.We have observed optically thick lines HCO+(1-0)and HCN(1-0)using the DLH 13.7-m telescope,and found 56 sources with a blue profile and no red profile in these two lines,which are likely to have infall motions,with a detection rate of 42%.This suggests that using CO data to restrict the sample can effectively improve the infall detection rate.Among these confirmed infall sources are 43 associated with Class 0/1 young stellar objects(YSOs),and 13 which are not.These 13 sources are probably associated with the sources in the earlier evolutionary stage.In comparison,the confirmed sources that are associated with Class 0/I YSOs have higher excitation temperatures and column densities,while the other sources are colder and have lower column densities.Most infall velocities of the sources that we confirmed are between 10-1 to 100 kms-1,which is consistent with previous studies.
其他文献
渤海海域垦利16-1地区沙河街组微体古生物非常发育,大量的数据分析表明,该地区沙河街组具有沉积环境变化快,化石类型丰富,生物序列更替快的特点,沙四段—沙—段共发育四个孢
进入深秋时节,越冬茬黄瓜纷纷定植到棚室中。深秋昼夜温差较大,露水重,随着气温的下降,白天拉开棚膜放风和降温,夜间需要关闭封口保温,这样的生长环境非常适合霜霉病和白粉病
采用XRD、OM、SEM和TEM对铸态V-5Cr-5Ti合金退火处理后组织结构进行分析。结果表明:在退火过程中,随着退火温度升高,铸态V-5Cr-5Ti合金第二相发生分解、扩散、聚集。第二相形
电吹风机是人们日常生活中常用于吹头发和定发型的家用电器,但用它也可用于治疗疾病。〈一〉电吹风治感冒。当出现有轻微头晕头痛、鼻塞、咽痛等感冒症状时,只有用接上电源
7月22日,江苏南通市盆景协会成立大会隆重召开。南通市建设局风景园林处季瑞元处长、南通市科协秘书长及学会部翁汉良部长等出席会议。南通市盆景协会的成立,得到了南通市政
本刊1994年第1期刊登的《自制无需调试的彩电选台有线遥控器》一文介绍的电路,设计完善,制作简单。但其有线控制方式是美中不足,使用起来不太方便。笔者在原电路基础上稍加
1褐腐病病菇幼时受侵染,无法进行分化,后期则形成不规则的灰白色“疙瘩头”。温度在20℃以上时,4~5天病菇色泽变暗,继之腐烂,渗出褐色、酱油状液汁,并腐烂、发臭;若棚温低于20
以往一直认为,脱水、酸中毒是急性腹泻的主要致死原因,最近统计分析表明,低血糖、心和脑血管意外是造成老年人急性腹泻致死的不容忽视的并发症.腹泻时少进食甚至禁食似乎成
Short timescale flux variations are closely related to the energy release process of magnetic reconnection during solar flares.Radio light curves at 1,2,3.75,9.
编辑同志:我自1990年始订阅《家庭医学》。这是我们最引为高兴之事。我是一个医务工作者,又是一位家庭主妇,所以很希望常能读到既能巩固我的事业知识,又能指导我的家庭生活