| Online-Ressource |
Verfasst von: | Lebouteiller, Vianney [VerfasserIn]  |
| Cormier, D. [VerfasserIn]  |
| Madden, S. C. [VerfasserIn]  |
| Galametz, M. [VerfasserIn]  |
| Hony, Sacha [VerfasserIn]  |
| Galliano, F. [VerfasserIn]  |
| Chevance, Mélanie [VerfasserIn]  |
| Lee, M.-Y. [VerfasserIn]  |
| Braine, J. [VerfasserIn]  |
| Polles, F. L. [VerfasserIn]  |
| Requeña-Torres, M. A. [VerfasserIn]  |
| Indebetouw, R. [VerfasserIn]  |
| Hughes, A. [VerfasserIn]  |
| Abel, N. [VerfasserIn]  |
Titel: | Physical conditions in the gas phases of the giant H II region LMC-N 11 |
Titelzusatz: | II. Origin of [C II] and fraction of CO-dark gas |
Verf.angabe: | V. Lebouteiller, D. Cormier, S.C. Madden, M. Galametz, S. Hony, F. Galliano, M. Chevance, M.-Y. Lee, J. Braine, F.L. Polles, M.A. Requeña-Torres, R. Indebetouw, A. Hughes, and N. Abel |
E-Jahr: | 2019 |
Jahr: | 10 December 2019 |
Umfang: | 30 S. |
Fussnoten: | Gesehen am 06.03.2020 |
Titel Quelle: | Enthalten in: Astronomy and astrophysics |
Ort Quelle: | Les Ulis : EDP Sciences, 1969 |
Jahr Quelle: | 2019 |
Band/Heft Quelle: | 632(2019) Artikel-Nummer A106, 30 Seiten |
ISSN Quelle: | 1432-0746 |
Abstract: | Context. The ambiguous origin of the [C II] 158μ m line in the interstellar medium complicates its use for diagnostics concerning the star-formation rate and physical conditions in photodissociation regions. Aims. We investigate the origin of [C II] in order to measure the total molecular gas content, the fraction of CO-dark H<sub>2<sub/> gas, and how these parameters are impacted by environmental effects such as stellar feedback.<i>Methods.<i/> We observed the giant H II region N 11 in the Large Magellanic Cloud with SOFIA/GREAT. The [C II] line is resolved in velocity and compared to H I and CO, using a Bayesian approach to decompose the line profiles. A simple model accounting for collisions in the neutral atomic and molecular gas was used in order to derive the H<sub>2<sub/> column density traced by C<sup>+<sup/>.<i>Results.<i/> The profile of [C II] most closely resembles that of CO, but the integrated [C II] line width lies between that of CO and that of H I. Using various methods, we find that [C II] mostly originates from the neutral gas. We show that [C II] mostly traces the CO-dark H<sub>2<sub/> gas but there is evidence of a weak contribution from neutral atomic gas preferentially in the faintest components (as opposed to components with low [C II]/CO or low CO column density). Most of the molecular gas is CO-dark. The CO-dark H<sub>2<sub/> gas, whose density is typically a few 100s cm<sup>−3<sup/> and thermal pressure in the range 10<sup>3.5−5<sup/> K cm<sup>−3<sup/>, is not always in pressure equilibrium with the neutral atomic gas. The fraction of CO-dark H<sub>2<sub/> gas decreases with increasing CO column density, with a slope that seems to depend on the impinging radiation field from nearby massive stars. Finally we extend previous measurements of the photoelectric-effect heating efficiency, which we find is constant across regions probed with <i>Herschel<i/>, with [C II] and [O I] being the main coolants in faint and diffuse, and bright and compact regions, respectively, and with polycyclic aromatic hydrocarbon emission tracing the CO-dark H<sub>2<sub/> gas heating where [C II] and [O I] emit.<i>Conclusions.<i/> We present an innovative spectral decomposition method that allows statistical trends to be derived for the molecular gas content using CO, [C II], and H I profiles. Our study highlights the importance of velocity-resolved photodissociation region (PDR) diagnostics and higher spatial resolution for H I observations as future steps. |
DOI: | doi:10.1051/0004-6361/201936303 |
URL: | Bitte beachten Sie: Dies ist ein Bibliographieeintrag. Ein Volltextzugriff für Mitglieder der Universität besteht hier nur, falls für die entsprechende Zeitschrift/den entsprechenden Sammelband ein Abonnement besteht oder es sich um einen OpenAccess-Titel handelt.
Volltext ; Verlag: https://doi.org/10.1051/0004-6361/201936303 |
| Volltext: https://www.aanda.org/articles/aa/abs/2019/12/aa36303-19/aa36303-19.html |
| DOI: https://doi.org/10.1051/0004-6361/201936303 |
Datenträger: | Online-Ressource |
Sprache: | eng |
K10plus-PPN: | 1691810819 |
Verknüpfungen: | → Zeitschrift |
Physical conditions in the gas phases of the giant H II region LMC-N 11 / Lebouteiller, Vianney [VerfasserIn]; 10 December 2019 (Online-Ressource)