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Resolution-dependent subsonic non-thermal line dispersion revealed by ALMA
Yue, Nan-Nan1,2,3; Li, Di1,2,4; Zhang, Qi-Zhou3; Zhu, Lei1,5; Henshaw, Jonathan6; Mardones, Diego7; Ren, Zhi-Yuan1
2021
Source PublicationRESEARCH IN ASTRONOMY AND ASTROPHYSICS
ISSN1674-4527
Volume21Issue:1Pages:9
AbstractWe report here Atacama Large Millimeter/submillimeter Array (ALMA) N2H+ (1-0) images of the Orion Molecular Cloud 2 and 3 (OMC-2/3) with high angular resolution (3 '' or 1200 au) and high spatial dynamic range. Combining a dataset from the ALMA main array, Atacama Compact Array (ACA), Nobeyama 45-m Telescope and Very Large Array (VLA) (providing temperature measurement on matching scales), we find that most of the dense gas in OMC-2/3 is subsonic (sigma(NT) / C-s = 0.62) with a mean line width (Delta upsilon) of 0.39 km s(-1) full width at half maximum (FWHM). This is markedly different from the majority of previous observations of massive star-forming regions. In contrast, line widths from the Nobeyama Telescope are transonic at 0.69 km s(-1) (sigma(NT) / C-s = 1.08). We demonstrated that the larger line widths obtained by the single-dish telescope arose from unresolved sub-structures within their respective beams. The dispersions from larger scales sigma(ls) (as traced by the Nobeyama Telescope) can be decomposed into three components such that sigma(2)(ls)=sigma(2)(ss)+sigma(2)(bm)+sigma(2)(rd) , where small-scale sigma(ss) is the line dispersion of each ALMA beam, bulk motion sigma(bm) is dispersion between peak velocity of each ALMA beam and sigma(rd) is the residual dispersion. Such decomposition, though purely empirical, appears to be robust throughout our data cubes. Apparent supersonic line widths, commonly found in massive molecular clouds, are thus likely due to the effect of poor spatial resolution. The observed non-thermal line dispersion (sometimes referred to as 'turbulence') transits from supersonic to subsonic at similar to 0.05 pc scales in the OMC-2/3 region. Such transition could be commonly found with sufficient spatial (not just angular) resolution, even in regions with massive young clusters, such as the Orion molecular clouds studied here.
Keywordstars: formation ISM: clouds ISM: molecules ISM: kinematics and dynamics
Funding OrganizationNational Natural Science Foundation of China ; National Natural Science Foundation of China ; CAS International Partnership Program ; CAS International Partnership Program ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; CAS International Partnership Program ; CAS International Partnership Program ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; CAS International Partnership Program ; CAS International Partnership Program ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; CAS International Partnership Program ; CAS International Partnership Program
DOI10.1088/1674-4527/21/1/24
Language英语
Funding ProjectNational Natural Science Foundation of China[11988101] ; National Natural Science Foundation of China[11725313] ; National Natural Science Foundation of China[11629302] ; CAS International Partnership Program[114A11KYSB20160008]
Funding OrganizationNational Natural Science Foundation of China ; National Natural Science Foundation of China ; CAS International Partnership Program ; CAS International Partnership Program ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; CAS International Partnership Program ; CAS International Partnership Program ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; CAS International Partnership Program ; CAS International Partnership Program ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; CAS International Partnership Program ; CAS International Partnership Program
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000616045400001
PublisherNATL ASTRONOMICAL OBSERVATORIES, CHIN ACAD SCIENCES
Citation statistics
Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/79625
Collection中国科学院国家天文台
Corresponding AuthorYue, Nan-Nan
Affiliation1.Chinese Acad Sci, Natl Astron Observ, Beijing 100101, Peoples R China
2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
3.Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
4.Univ KwaZulu Natal, NAOC UKZN Computat Astrophys Ctr, ZA-4000 Durban, South Africa
5.China Chile Joint Ctr Astron, Chinese Acad Sci South Amer Ctr Astron, Camino Observ 1515, Santiago, Chile
6.Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany
7.Univ Chile, Dept Astron, Casilla 36-D, Santiago, Chile
Recommended Citation
GB/T 7714
Yue, Nan-Nan,Li, Di,Zhang, Qi-Zhou,et al. Resolution-dependent subsonic non-thermal line dispersion revealed by ALMA[J]. RESEARCH IN ASTRONOMY AND ASTROPHYSICS,2021,21(1):9.
APA Yue, Nan-Nan.,Li, Di.,Zhang, Qi-Zhou.,Zhu, Lei.,Henshaw, Jonathan.,...&Ren, Zhi-Yuan.(2021).Resolution-dependent subsonic non-thermal line dispersion revealed by ALMA.RESEARCH IN ASTRONOMY AND ASTROPHYSICS,21(1),9.
MLA Yue, Nan-Nan,et al."Resolution-dependent subsonic non-thermal line dispersion revealed by ALMA".RESEARCH IN ASTRONOMY AND ASTROPHYSICS 21.1(2021):9.
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