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- W3214541736 abstract "HCN is considered a good tracer of the dense molecular gas that serves as fuel for star formation. However, recent large-scale surveys of giant molecular clouds (GMCs) have detected extended HCN line emission. Such observations often resolve the HCN J=1-0 hyperfine structure (HFS). A precise determination of the physical conditions of the gas requires treating the HFS line overlap effects. Here, we study the HCN HFS excitation and line emission using nonlocal radiative transfer models that include line overlaps and new HFS-resolved collisional rate coefficients for inelastic collisions of HCN with both para-H2 and ortho-H2 (computed via the scaled-IOS approximation up to Tk=500 K). In addition, we account for the role of electron collisions in the HFS level excitation. We find that line overlap and opacity effects frequently produce anomalous HCN J=1-0 HFS line intensity ratios (inconsistent with the common assumption of the same Tex for all HFS lines) as well as anomalous HFS line width ratios. Line overlap and electron collisions also enhance the excitation of the higher J rotational lines. Electron excitation becomes important for molecular gas with H2 densities below a few 10^5 cm-3 and electron abundances above ~10^-5. In particular, electron excitation can produce low-surface-brightness HCN emission from very extended but low-density gas in GMCs. The existence of such a widespread HCN emission component may affect the interpretation of the extragalactic relationship HCN luminosity versus star-formation rate. Alternatively, extended HCN emission may arise from dense star-forming cores and become resonantly scattered by large envelopes of lower density gas. There are two scenarios - namely, electron-assisted (weakly) collisionally excited versus scattering - that lead to different HCN J=1-0 HFS intensity ratios, which can be tested on the basis of observations." @default.
- W3214541736 created "2021-11-22" @default.
- W3214541736 creator A5018324173 @default.
- W3214541736 creator A5036135230 @default.
- W3214541736 creator A5042080453 @default.
- W3214541736 date "2022-01-27" @default.
- W3214541736 modified "2023-10-16" @default.
- W3214541736 title "Anomalous HCN emission from warm giant molecular clouds" @default.
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- W3214541736 cites W1980533101 @default.
- W3214541736 cites W1981553890 @default.
- W3214541736 cites W1988894843 @default.
- W3214541736 cites W1991183902 @default.
- W3214541736 cites W1995088170 @default.
- W3214541736 cites W2000083902 @default.
- W3214541736 cites W2003054212 @default.
- W3214541736 cites W2005509839 @default.
- W3214541736 cites W2008638911 @default.
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- W3214541736 cites W2014794389 @default.
- W3214541736 cites W2018038719 @default.
- W3214541736 cites W2020814246 @default.
- W3214541736 cites W2024389974 @default.
- W3214541736 cites W2026096786 @default.
- W3214541736 cites W2030273724 @default.
- W3214541736 cites W2034229231 @default.
- W3214541736 cites W2038536296 @default.
- W3214541736 cites W2060110495 @default.
- W3214541736 cites W2063585257 @default.
- W3214541736 cites W2071862938 @default.
- W3214541736 cites W2073896865 @default.
- W3214541736 cites W2076783262 @default.
- W3214541736 cites W2086284269 @default.
- W3214541736 cites W2093342937 @default.
- W3214541736 cites W2094993439 @default.
- W3214541736 cites W2098004592 @default.
- W3214541736 cites W2101681357 @default.
- W3214541736 cites W2106648105 @default.
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- W3214541736 cites W2141128460 @default.
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- W3214541736 cites W2336117971 @default.
- W3214541736 cites W2366080100 @default.
- W3214541736 cites W2590070952 @default.
- W3214541736 cites W2611006803 @default.
- W3214541736 cites W2615550982 @default.
- W3214541736 cites W3023166431 @default.
- W3214541736 cites W3040989661 @default.
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- W3214541736 cites W3099488523 @default.
- W3214541736 cites W3099571422 @default.
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- W3214541736 cites W3100538755 @default.
- W3214541736 cites W3100541594 @default.
- W3214541736 cites W3100970929 @default.
- W3214541736 cites W3101065350 @default.
- W3214541736 cites W3101396159 @default.
- W3214541736 cites W3101920590 @default.
- W3214541736 cites W3102529632 @default.
- W3214541736 cites W3104013481 @default.
- W3214541736 cites W3104029039 @default.
- W3214541736 cites W3104127602 @default.
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- W3214541736 cites W3105094438 @default.
- W3214541736 cites W3105339184 @default.
- W3214541736 cites W3105926414 @default.
- W3214541736 cites W3106393370 @default.
- W3214541736 cites W3106493273 @default.
- W3214541736 cites W3122655791 @default.
- W3214541736 cites W3123957495 @default.
- W3214541736 cites W3134185300 @default.
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- W3214541736 cites W3162249335 @default.
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- W3214541736 doi "https://doi.org/10.1051/0004-6361/202142210" @default.
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