First results from the herschel and ALMA spectroscopic surveys of the SMC: The relationship between [C II]-bright gas and CO-bright gas at low metallicity
Author
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Jameson, Katherine E.
Author
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Bolatto, Alberto D.
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Wolfire, Mark
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Warren, Steven R.
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Herrera Camus, Rodrigo
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Croxall, Kevin
Author
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Pellegrini, Eric W.
Author
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Smith, John David
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Rubio López, Mónica
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Indebetouw, Remy
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Israel, Frank P.
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Meixner, Margaret
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Roman Duval, Julia
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Loon, Jacco Th. van
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Muller, Erik
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Verdugo, Celia
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Zinnecker, Hans
Author
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Okada, Yoko
Admission date
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2018-07-27T20:09:05Z
Available date
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2018-07-27T20:09:05Z
Publication date
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2018
Cita de ítem
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Astrophysical Journal Volumen: 853 Número: 2 Número de artículo: 111
es_ES
Identifier
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10.3847/1538-4357/aaa4bb
Identifier
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https://repositorio.uchile.cl/handle/2250/150407
Abstract
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The Small Magellanic Cloud (SMC) provides the only laboratory to study the structure of molecular gas at high resolution and low metallicity. We present results from the Herschel Spectroscopic Survey of the SMC (HS3), which mapped the key far-IR cooling lines [C II], [O I], [N II], and [O III] in five star-forming regions, and new ALMA 7 m array maps of (CO)-C-12 and (CO)-C-13 (2-1) with coverage overlapping four of the five HS3 regions. We detect [C II] and [O I] throughout all of the regions mapped. The data allow us to compare the structure of the molecular clouds and surrounding photodissociation regions using (CO)-C-13, (CO)-C-12, [C II], and [O I] emission at less than or similar to 10 '' (<3 pc) scales. We estimate A(V) using far-IR thermal continuum emission from dust and find that the CO/[C II] ratios reach the Milky Way value at high A(V) in the centers of the clouds and fall to similar to 1/5-1/10x the Milky Way value in the outskirts, indicating the presence of translucent molecular gas not traced by bright (CO)-C-12 emission. We estimate the amount of molecular gas traced by bright [C II] emission at low A(V) and bright (CO)-C-12 emission at high A(V). We find that most of the molecular gas is at low A(V) and traced by bright [C II] emission, but that faint (CO)-C-12 emission appears to extend to where we estimate that the H-2-to-H I transition occurs. By converting our H-2 gas estimates to a CO-to-H-2 conversion factor (X-CO), we show that X-CO is primarily a function of A(V), consistent with simulations and models of low-metallicity molecular clouds.
es_ES
Patrocinador
dc.description.sponsorship
ADS/JAO.ALMA
2015.1.00581.S
2013.1.00652.S
APEX data from project
C-093.F-9711-2014
Universities Space Research Association, Inc. (USRA), under NASA
NAS2-97001
Deutsches SOFIA Institut (DSI) under DLR
50 OK 0901
NASA-USRA
SOF030120
SOF040151
CAREER grant
NSF-AST0955836
NSF-AST1139998
NASA-JPL
1454733
NRAO Student Observer Support program
347065
CONICYT (Chile) through FONDECYT
1140839
project BASAL
PFB-06
USRA-SOF030120
First results from the herschel and ALMA spectroscopic surveys of the SMC: The relationship between [C II]-bright gas and CO-bright gas at low metallicity