Astron. Astrophys. 346, 936-946 (1999)

Distribution of gas, dust and the 6613 Å DIB carrier in the Perseus OB2 association ^*

P. Sonnentrucker ^1,2, B.H. Foing ^2,3, M. Breitfellner ⁴ and P. Ehrenfreund <sup>5

1</sup> Observatoire de Strasbourg, 11 rue de l'Université, F-67000 Strasbourg, France
² Solar System Division, ESA Space Science Department, ESTEC/SO, PB 299, 2200 AG Noordwijk, The Netherlands
³ Institut d'Astrophysique Spatiale, CNRS, Bat 121, Campus d'Orsay, F-91405 Orsay, France
⁴ ISO Data Center, Astrophysics Division, Space Science Department of ESA, Villafranca, P.O. Box 50727, E-28080 Madrid, Spain
⁵ Leiden Observatory, P.O. Box 9513, 2300 RA Leiden, The Netherlands

Received 16 December 1998 / Accepted 12 March 1999

Abstract

We present a study of the spatial distribution of the 6613 Å DIB carrier in the Perseus OB2 association based on high resolution observations toward lines of sight representing different interstellar environments. We determined that in the studied region, the 6613 Å DIB carrier is concentrated in two distinct clouds with velocities of 1.4 ( 0.4) and 12.0 ( 0.9) km s^-1. We compared the 6613 Å DIB carrier's velocity with the NaI velocity distribution derived from our survey measurements, as well as with CO, OH, HI and CaII measurements from the literature. We conclude that the behaviour of the carrier of the 6613 Å DIB follows the overall expansion motion of the gas in the association. The DIB velocity is directly linked to that of CaII and HI . The DIB total column density is proportional to the total column density of CaII and HI making those atoms good tracers of the 6613 Å DIB carrier. Those new results support the assumption that the 6613 Å DIB would arise from a gas phase molecule, possibly single-ionized (Sonnentrucker et al. 1997). We also conclude that the DIB carrier is distributed in shell structures over the whole association. We finally show from the DIB velocity structure that the DIB carrier, gas and dust are well mixed toward the association but that the DIB shells have an angular extent twice larger than that of the dust.

Key words: line: profiles ISM: clouds ISM: dust, extinction ISM: lines and bands ISM: molecules

* Based on observations with OHP 1.52m Telescope and Aurélie spectrograph.

Send offprint requests to: P. Sonnentrucker

© European Southern Observatory (ESO) 1999

Online publication: June 17, 1999

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