First hyperfine resolved far-infrared OH spectrum from a star-forming region
CHAVARRIA, L.
Observatoire aquitain des sciences de l'univers [OASU]
Université Sciences et Technologies - Bordeaux 1 [UB]
Laboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
Observatoire aquitain des sciences de l'univers [OASU]
Université Sciences et Technologies - Bordeaux 1 [UB]
Laboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
VAN DISHOECK, E. F.
Max-Planck-Institut für Extraterrestrische Physik [MPE]
Leiden Observatory [Leiden]
Max-Planck-Institut für Extraterrestrische Physik [MPE]
Leiden Observatory [Leiden]
VAN DER TAK, F. F. S.
Kapteyn Astronomical Institute [Groningen]
SRON Netherlands Institute for Space Research [SRON]
Kapteyn Astronomical Institute [Groningen]
SRON Netherlands Institute for Space Research [SRON]
HERPIN, Fabrice
Observatoire aquitain des sciences de l'univers [OASU]
Université Sciences et Technologies - Bordeaux 1 [UB]
Laboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
< Leer menos
Observatoire aquitain des sciences de l'univers [OASU]
Université Sciences et Technologies - Bordeaux 1 [UB]
Laboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
Idioma
en
Article de revue
Este ítem está publicado en
Astronomy and Astrophysics - A&A. 2011, vol. 531, p. id.L16
EDP Sciences
Resumen en inglés
OH is an important molecule in the H2O chemistry and the cooling budget of star-forming regions. The goal of the Herschel key program 'Water in Star-forming regions with Herschel' (WISH) is to study H2O and related species ...Leer más >
OH is an important molecule in the H2O chemistry and the cooling budget of star-forming regions. The goal of the Herschel key program 'Water in Star-forming regions with Herschel' (WISH) is to study H2O and related species during protostellar evolution. Our aim in this letter is to assess the origin of the OH emission from star-forming regions and constrain the properties of the emitting gas. High-resolution observations of the OH 2Pi1/2 J = 3/2-1/2 triplet at 1837.8 GHz (163.1 micron) towards the high-mass star-forming region W3 IRS 5 with the Heterodyne Instrument for the Far-Infrared (HIFI) on Herschel reveal the first hyperfine velocity-resolved OH far-infrared spectrum of a star-forming region. The line profile of the OH emission shows two components: a narrow component (FWHM approx. 4-5 km/s) with partially resolved hyperfine structure resides on top of a broad (FWHM approx. 30 km/s) component. The narrow emission agrees well with results from radiative transfer calculations of a spherical envelope model for W3 IRS 5 with a constant OH abundance of approx. 8e-9. Comparison with H2O yields OH/H2O abundance ratios of around 1e-3 for T > 100 K and around unity for T < 100K, consistent with the current picture of the dense cloud chemistry with freeze-out and photodesorption. The broad component is attributed to outflow emission. An abundance ratio of OH/H2O > 0.028 in the outflow is derived from comparison with results of water line modeling. This ratio can be explained by a fast J-type shock or a slower UV-irradiated C-type shock.< Leer menos
Palabras clave en inglés
astrochemistry
stars: formation
ISM: magnetic fields
ISM: individual objects: W3 IRS 5
ISM: jets and outflows
Orígen
Importado de HalCentros de investigación