期刊文献+
共找到4篇文章
< 1 >
每页显示 20 50 100
Molecular Oxygen Abundance in Galactic Massive Star Formation Regions Based on SWAS Observations
1
作者 Bing-Ru Wang Di Li +9 位作者 Paul F.Goldsmith Jingwen Wu Chao-Wei Tsai Donghui Quan Xia Zhang Junzhi Wang Gary J.Melnick Jin-Zeng Li Gary A.Fuller jinjin xie 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第9期83-98,共16页
Molecular oxygen abundance is a key parameter in understanding the chemical network of the interstellar medium.We estimate the molecular oxygen column density and abundance for a sample of Galactic massive star format... Molecular oxygen abundance is a key parameter in understanding the chemical network of the interstellar medium.We estimate the molecular oxygen column density and abundance for a sample of Galactic massive star formation regions based on observations from the Submillimiter Wave Astronomy Satellite(SWAS)survey.We obtained an averaged O_(2)spectrum based on this sample using the(SWAS)survey data(O_(2),487.249 GHz,N=3-1,J=3-2).No emission or absorption feature is seen around the supposed central velocity with a total integration time of t_(total)=8.67×10^(3)hr and an rms noise per channel of 1.45 m K.Assuming a kinetic temperature T_(kin)=30 K,we derive the 3σupper limit of the O_(2)column density to be 3.3×10^(15)cm^(-2),close to the lowest values reported in Galactic massive star formation regions in previous studies.The corresponding O_(2)abundance upper limit is6.7×10^(-8),lower than all previous results based on SWAS observations and is close to the lowest reported value in massive star formation regions.On a galactic scale,our statistical results confirm a generally low O_(2)abundance for Galactic massive star formation regions.This abundance is also lower than results reported in extragalactic sources. 展开更多
关键词 ISM:molecules galaxies:abundances ISM:lines and bands Galaxy:abundances
下载PDF
Updated Inventory of Carbon Monoxide in the Taurus Molecular Cloud
2
作者 Yan Duan Di Li +4 位作者 Laurent Pagani Paul F.Goldsmith Tao-Chung Ching Chen Wang jinjin xie 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第9期56-65,共10页
The most extensive survey of carbon monoxide(CO)gas in the Taurus molecular cloud relied on ^(12)CO and ^(13)CO J=1→0 emission only,distinguishing the region where ^(12)CO is detected without ^(13)CO(named mask 1 reg... The most extensive survey of carbon monoxide(CO)gas in the Taurus molecular cloud relied on ^(12)CO and ^(13)CO J=1→0 emission only,distinguishing the region where ^(12)CO is detected without ^(13)CO(named mask 1 region)from the one where both are detected(mask 2 region)(Goldsmith et al.2008;Pineda et al.2010).We have taken advantage of recent ^(12)CO J=3→2 James Clerk Maxwell Telescope observations,where they include mask 1regions to estimate density,temperature,and N(CO)with a large velocity gradient model.This represents 1395 pixels out of~1.2 million in the mark 1 region.Compared to Pineda et al.(2010)results and assuming a Tkin of 30 K,we find a higher volume density of molecular hydrogen of 3.3×10^(3) cm^(-3),compared to their 250-700 cm^(-3),and a CO column density of 5.7×10^(15)cm^(-2),about a quarter of their value.The differences are important and show the necessity to observe several CO transitions to better describe the intermediate region between the dense cloud and the diffuse atomic medium.Future observations to extend the ^(12)CO J=3→2 mapping further away from the ^(13)COdetected region comprising mask 1 are needed to revisit our understanding of the diffuse portions of dark clouds. 展开更多
关键词 SUBMILLIMETER ISM-ISM clouds-ISM MOLECULES
下载PDF
The Distribution of UV Radiation Field in the Molecular Clouds of Gould Belt
3
作者 Jifeng Xia Ningyu Tang +5 位作者 Qijun Zhi Sihan Jiao jinjin xie Gary A.Fuller Paul F.Goldsmith Di Li 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2022年第8期206-217,共12页
The distribution of ultraviolet(UV)radiation field provides critical constraints on the physical environments of molecular clouds.Within 1 kpc of our solar system and fostering protostars of different masses,the giant... The distribution of ultraviolet(UV)radiation field provides critical constraints on the physical environments of molecular clouds.Within 1 kpc of our solar system and fostering protostars of different masses,the giant molecular clouds in the Gould Belt present an excellent opportunity to resolve the UV field structure in star-forming regions.We performed spectral energy distribution(SED)fitting of the archival data from the Herschel Gould Belt Survey(HGBS).Dust radiative transfer analysis with the DUSTY code was applied to 23 regions in 14 molecular complexes of the Gould Belt,resulting in the spatial distribution of the radiation field in these regions.For 10 of 15 regions with independent measurements of star formation rate,their star formation rate and UV radiation intensity largely conform to a linear correlation found in previous studies. 展开更多
关键词 ISM:clouds (ISM:)dust EXTINCTION radiative transfer
下载PDF
The TMRT K band observations towards 26 infrared dark clouds:NH_3, CCS, and HC_3N
4
作者 jinjin xie Gary A.Fuller +9 位作者 Di Li Longfei Chen Zhiyuan Ren Jingwen Wu Yan Duan Junzhi Wang Juan Li Nicolas Peretto Tie Liu Zhiqiang Shen 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2021年第7期126-136,共11页
We present one of the first Shanghai Tian Ma Radio Telescope (TMRT) K Band observations towards a sample of 26 infrared dark clouds (IRDCs).We observed the (1,1),(2,2),(3,3),and (4,4) transitions of NH_(3) together wi... We present one of the first Shanghai Tian Ma Radio Telescope (TMRT) K Band observations towards a sample of 26 infrared dark clouds (IRDCs).We observed the (1,1),(2,2),(3,3),and (4,4) transitions of NH_(3) together with CCS (2_(1)–>1_(0)) and HC_(3)NJ=2-1,simultaneously.The survey dramatically increases the existing CCS-detected IRDC sample from 8 to 23,enabling a better statistical study of the ratios of carbon-chain molecules (CCM) to N-bearing molecules in IRDCs.With the newly developed hyperfine group ratio (HFGR) method of fitting NH_(3) inversion lines,we found the gas temperature to be between 10 and18 K.The column density ratios of CCS to NH_(3) for most of the IRDCs are less than 10^(-2),distinguishing IRDCs from low-mass star-forming regions.We carried out chemical evolution simulations based on a three-phase chemical model NAUTILUS.Our measurements of the column density ratios between CCM and NH_(3) are consistent with chemical evolutionary ages of 10^(5) yr in the models.Comparisons of the data and chemical models suggest that CCS,HC_(3)N,and NH_(3) are sensitive to the chemical evolutionary stages of the sources. 展开更多
关键词 star formation infrared dark clouds chemical evolution
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部