Herschel observations of the hydroxyl radical (OH) in young stellar objects
Journal article, 2010

Aims: \ldquoWater In Star-forming regions with Herschel\rdquo (WISH) is a Herschel key program investigating the water chemistry in young stellar objects (YSOs) during protostellar evolution. Hydroxyl (OH) is one of the reactants in the chemical network most closely linked to the formation and destruction of H_2O. High-temperature (T \gap 250 K) chemistry connects OH and H_2O through the OH + H_2 Leftrightarrow H_2O + H reactions. Formation of H_2O from OH is efficient in the high-temperature regime found in shocks and the innermost part of protostellar envelopes. Moreover, in the presence of UV photons, OH can be produced from the photo-dissociation of H_2O through H_2O + γ_UV Rightarrow OH + H. Methods: High-resolution spectroscopy of the 163.12 µm triplet of OH towards HH 46 and NGC 1333 IRAS 2A was carried out with the Heterodyne Instrument for the Far Infrared (HIFI) on board the Herschel Space Observatory. The low- and intermediate-mass protostars HH 46, TMR 1, IRAS 15398-3359, DK Cha, NGC 7129 FIRS 2, and NGC 1333 IRAS 2A were observed with the Photodetector Array Camera and Spectrometer (PACS) on Herschel in four transitions of OH and two [O i] lines. Results: The OH transitions at 79, 84, 119, and 163 µm and [O i] emission at 63 and 145 µm were detected with PACS towards the class I low-mass YSOs as well as the intermediate-mass and class I Herbig Ae sources. No OH emission was detected from the class 0 YSO NGC 1333 IRAS 2A, though the 119 µm was detected in absorption. With HIFI, the 163.12 µm was not detected from HH 46 and only tentatively detected from NGC 1333 IRAS 2A. The combination of the PACS and HIFI results for HH 46 constrains the line width (FWHM \gap 11 km s^-1) and indicates that the OH emission likely originates from shocked gas. This scenario is supported by trends of the OH flux increasing with the [O i] flux and the bolometric luminosity, as found in our sample. Similar OH line ratios for most sources suggest that OH has comparable excitation temperatures despite the different physical properties of the sources.

ISM: molecules

stars: formation

astrochemistry

ISM: individual objects: HH 46

ISM: jets and outflows

Author

S. F. Wampfler

Swiss Federal Institute of Technology in Zürich (ETH)

G. J. Herczeg

Max Planck Institute

S. Bruderer

Swiss Federal Institute of Technology in Zürich (ETH)

A. O. Benz

Swiss Federal Institute of Technology in Zürich (ETH)

E. F. van Dishoeck

Max Planck Institute

Leiden University

L. Kristensen

Leiden University

R. Visser

Leiden University

S. Doty

Denison University

M. Melchior

Swiss Federal Institute of Technology in Zürich (ETH)

University of Applied Sciences Northwestern Switzerland, School of Enginnering

T. A. van Kempen

Harvard-Smithsonian Center for Astrophysics

U. A. Yildiz

Leiden University

C. Dedes

Swiss Federal Institute of Technology in Zürich (ETH)

J. R. Goicoechea

Centro de Astrobiologia (CAB)

A. Baudry

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

G. J. Melnick

Harvard-Smithsonian Center for Astrophysics

R. Bachiller

Spanish National Observatory (OAN)

M. Benedettini

University of Rome Tor Vergata

E. A. Bergin

University of Michigan

Per Bjerkeli

Chalmers, Earth and Space Sciences, Onsala Space Observatory

G. A. Blake

California Institute of Technology (Caltech)

S. Bontemps

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

J. Braine

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

P. Caselli

University of Leeds

Arcetri Astrophysical Observatory

J. Cernicharo

Centro de Astrobiologia (CAB)

C. Codella

Arcetri Astrophysical Observatory

F. Daniel

Centro de Astrobiologia (CAB)

A. M. di Giorgio

University of Rome Tor Vergata

C. Dominik

Anton Pannekoek Institute for Astronomy

Radboud University

P. Encrenaz

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

M. Fich

University of Waterloo

A. Fuente

Spanish National Observatory (OAN)

T. Giannini

Osservatorio Astronomico di Roma

T. de Graauw

Netherlands Institute for Space Research (SRON)

F. Helmich

Netherlands Institute for Space Research (SRON)

F. Herpin

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

M. R. Hogerheijde

Leiden University

T. Jacq

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

D. Johnstone

National Research Council Canada

University of Victoria

J. K. Jorgensen

University of Copenhagen

B. Larsson

Stockholm University

D. Lis

California Institute of Technology (Caltech)

René Liseau

Chalmers, Department of Radio and Space Science, Radio Astronomy and Astrophysics

M. Marseille

Netherlands Institute for Space Research (SRON)

C. McCoey

Western University

University of Waterloo

D. A. Neufeld

Johns Hopkins University

B. Nisini

Osservatorio Astronomico di Roma

Michael Olberg

Chalmers, Department of Radio and Space Science, Radio Astronomy and Astrophysics

B. Parise

Max Planck Institute

J. C. Pearson

Jet Propulsion Laboratory, California Institute of Technology

R. Plume

University of Calgary

C. Risacher

Netherlands Institute for Space Research (SRON)

J. Santiago-García

Instituto de Radioastronomía Milimétrica

P. Saraceno

University of Rome Tor Vergata

R. Shipman

Netherlands Institute for Space Research (SRON)

M. Tafalla

Spanish National Observatory (OAN)

F. F. S. van der Tak

University of Groningen

Netherlands Institute for Space Research (SRON)

F. Wyrowski

Max Planck Institute

P. Roelfsema

Netherlands Institute for Space Research (SRON)

W. Jellema

Netherlands Institute for Space Research (SRON)

P. Dieleman

Netherlands Institute for Space Research (SRON)

E. Caux

University of Toulouse

Institut National des Sciences de l'Univers

J. Stutzki

University of Cologne

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 521 1 Art. Nr. L36- L36

Subject Categories

Astronomy, Astrophysics and Cosmology

Roots

Basic sciences

DOI

10.1051/0004-6361/201015112

More information

Latest update

5/23/2019