OH far-infrared emission from low- and intermediate-mass protostars surveyed with Herschel-PACS

Autor: Javier R. Goicoechea, Alain Baudry, S. F. Wampfler, Simon Bruderer, C. McCoey, Lars E. Kristensen, Steven D. Doty, Gregory J. Herczeg, E. F. van Dishoeck, Agata Karska, T. Giannini, Arnold O. Benz, B. Larsson
Přispěvatelé: Institute of Astronomy [ETH Zürich], Department of Physics [ETH Zürich] (D-PHYS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Max-Planck-Institut für Extraterrestrische Physik (MPE), foreign laboratories (FL), CERN [Genève], Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Department of Physics and Astronomy [Granville, OH], Denison University, FORMATION STELLAIRE 2013, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Jazyk: angličtina
Rok vydání: 2013
Předmět:
astro-ph.SR
010504 meteorology & atmospheric sciences
astro-ph.GA
Young stellar object
FOS: Physical sciences
Excitation temperature
Astrophysics
01 natural sciences
Luminosity
Far infrared
0103 physical sciences
Radiative transfer
Protostar
010303 astronomy & astrophysics
Astrophysics::Galaxy Astrophysics
Solar and Stellar Astrophysics (astro-ph.SR)
0105 earth and related environmental sciences
Line (formation)
Physics
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
Astronomy and Astrophysics
[PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
Astrophysics - Astrophysics of Galaxies
Astrophysics - Solar and Stellar Astrophysics
13. Climate action
Space and Planetary Science
Astrophysics of Galaxies (astro-ph.GA)
Excitation
Zdroj: Astronomy & Astrophysics, 552, A56
Astronomy and Astrophysics-A&A
Astronomy and Astrophysics-A&A, EDP Sciences, 2013, 552, pp.id.A56. ⟨10.1051/0004-6361/201219929⟩
Wampfler, S F, Bruderer, S, Karska, A, J. Herczeg, G, F. van Dishoeck, E, E. Kristensen, L, R. Goicoechea, J, O. Benz, A, D. Doty, S, McCoey, C, Baudry, A, Giannini, T & Larsson, B 2013, ' OH far-infrared emission from low-and intermediate-mass protostars surveyed with Herschel-PACS ', Astronomy & Astrophysics, vol. 552, A56 . https://doi.org/10.1051/0004-6361/201219929
ISSN: 0004-6361
Popis: OH is a key species in the water chemistry of star-forming regions, because its presence is tightly related to the formation and destruction of water. This paper presents OH observations from 23 low- and intermediate-mass young stellar objects obtained with the PACS integral field spectrometer on-board Herschel in the context of the Water In Star-forming Regions with Herschel (WISH) key program. Most low-mass sources have compact OH emission (< 5000 AU scale), whereas the OH lines in most intermediate-mass sources are extended over the whole PACS detector field-of-view (> 20000 AU). The strength of the OH emission is correlated with various source properties such as the bolometric luminosity and the envelope mass, but also with the OI and H2O emission. Rotational diagrams for sources with many OH lines show that the level populations of OH can be approximated by a Boltzmann distribution with an excitation temperature at around 70 K. Radiative transfer models of spherically symmetric envelopes cannot reproduce the OH emission fluxes nor their broad line widths, strongly suggesting an outflow origin. Slab excitation models indicate that the observed excitation temperature can either be reached if the OH molecules are exposed to a strong far-infrared continuum radiation field or if the gas temperature and density are sufficiently high. Using realistic source parameters and radiation fields, it is shown for the case of Ser SMM1 that radiative pumping plays an important role in transitions arising from upper level energies higher than 300 K. The compact emission in the low-mass sources and the required presence of a strong radiation field and/or a high density to excite the OH molecules points towards an origin in shocks in the inner envelope close to the protostar.
Accepted for publication in Astronomy and Astrophysics. Abstract abridged
Databáze: OpenAIRE
Externí odkaz: