Volume 425, Number 1, October I 2004
|Page(s)||151 - 162|
|Section||Interstellar and circumstellar matter|
|Published online||10 September 2004|
Interstellar absorption lines toward Cep OB4*
Max-Planck Institut für Astronomie (MPIA), Königstuhl 17, 69117 Heidelberg, Germany e-mail: email@example.com; firstname.lastname@example.org
Accepted: 10 June 2004
An analysis of optical echelle spectra towards nine stars in the Cep OB4 association is presented. Interstellar absorption lines which arise in the (1, 0) and (2, 0) bands of the CN A – X red system towards BD+66° 1661, BD+66° 1674, and BD+66° 1675 are used to infer accurate CN column densities N(CN). A comparison with earlier measurements in the CN violet system allows to infer a CN Doppler b parameter of b(CN km s-1. Molecular carbon absorption lines which arise in the (1, 0), (2, 0) and (3, 0) bands of the C2 A – X Phillips system is used to infer gaskinetic temperatures of K and densities of cm-3 towards BD+66° 1661 and BD+66° 1675, and a temperature of K and a density of cm-3 towards BD+66° 1674. The R(1) line of the (0, 0) band of the CH A system is detected towards 6 stars. A tight correlation exists between N(C2) and N(CH). N(CN) increases with N(CH) and with N(C2). Interstellar CH+ is marginally detected towards four stars. Inferred CH+ column densities are significantly lower than towards other lines of sight with similar reddening. The velocity structure towards Cep OB4 and the chemical abundances suggest that CN, C2, CH, and CH+ are formed in quiescent material. A previous suggestion that the molecules form in a photon-dominated region close to the stars is not supported by the observations.
Key words: ISM: abundances / ISM: clouds / ISM: molecules / ISM: lines and bands
© ESO, 2004
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.