Herschel/HIFI detections of hydrides towards AFGL 2591 Envelope emission versus tenuous cloud absorption
Journal article, 2010

The Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory allows the first observations of light diatomic molecules at high spectral resolution and in multiple transitions. Here, we report deep integrations using HIFI in different lines of hydrides towards the high-mass star forming region AFGL 2591. Detected are CH, CH+, NH, OH+, H2O+, while NH+ and SH+ have not been detected. All molecules except for CH and CH+ are seen in absorption with low excitation temperatures and at velocities different from the systemic velocity of the protostellar envelope. Surprisingly, the CH(J(F,P) = 3/2(2),(-) - 1/2(1,+)) and CH+(J = 1-0, J = 2-1) lines are detected in emission at the systemic velocity. We can assign the absorption features to a foreground cloud and an outflow lobe, while the CH and CH+ emission stems from the envelope. The observed abundance and excitation of CH and CH+ can be explained in the scenario of FUV irradiated outflow walls, where a cavity etched out by the outflow allows protostellar FUV photons to irradiate and heat the envelope at larger distances driving the chemical reactions that produce these molecules.

stars: formation





ISM: molecules




objects: AFGL 2591

ISM: individual


star-forming regions



S. Bruderer

A. O. Benz

E. F. van Dishoeck

M. Melchior

S. Doty

F. F. S. van der Tak

P. Stauber

S. F. Wampfler

C. Dedes

U. A. Yildiz

L. Pagani

T. Giannini

T. de Graauw

N. Whyborn

D. Teyssier

W. Jellema

R. Shipman

R. Schieder

N. Honingh

E. Caux

W. Bachtold

A. Csillaghy

C. Monstein

R. Bachiller

A. Baudry

M. Benedettini

E. A. Bergin

Per Bjerkeli

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

G. A. Blake

S. Bontemps

J. Braine

P. Caselli

J. Cernicharo

C. Codella

F. Daniel

A. M. di Giorgio

C. Dominik

P. Encrenaz

M. Fich

A. Fuente

J. R. Goicoechea

F. Helmich

G. J. Herczeg

F. Herpin

M. R. Hogerheijde

T. Jacq

D. Johnstone

J. K. Jorgensen

L. Kristensen

B. Larsson

D. Lis

René Liseau

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

M. Marseille

C. McCoey

G. J. Melnick

D. A. Neufeld

B. Nisini

Michael Olberg

Chalmers, Earth and Space Sciences, Onsala Space Observatory

B. Parise

J. C. Pearson

R. Plume

C. Risacher

J. Santiago-García

P. Saraceno

M. Tafalla

T. A. van Kempen

R. Visser

F. Wyrowski

Astronomy and Astrophysics

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

Vol. 521 1 Article Number: L44 - L44

Subject Categories

Astronomy, Astrophysics and Cosmology



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