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Astron. Astrophys. 346, 199-204 (1999)


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Diffuse band shifts: a possible explanation

J. Kreowski 1 and J. MayoGreenberg 2

1 Nicolaus Copernicus University, Center for Astronomy, Gagarina 11, PL-87-100 Toru, Poland (jacek@astri.uni.torun.pl)
2 Raymond and Beverly Sackler Laboratory for Astrophysics, University of Leiden, P.O.Box 9513, 2300 RA Leiden, The Netherlands (greenber@strw.leidenuniv.nl)

Received 30 April 1998 / Accepted 2 March 1999

Abstract

We discuss the behaviour of broad and narrow diffuse interstellar bands inside the Orion association. The peculiarities, observed in this region, such as enormous weakness of some features as well as wavelength shifts of others suggest that the diffuse band carriers - most probably some sort of complex molecules - accrete onto grain surfaces. It appears that the processes which occur upon accretion make the narrow DIBs vanish while the broader features are less attenuated but always red-shifted. The observed shapes of interstellar extinction curves suggest that where this happens the small dust grains which are responsible for the FUV extinction are also reduced in numbers which naturally goes along with gas accretion and increased ratio of total to selective extinction.

Key words: ISM: dust, extinction – ISM: lines and bands – ISM: molecules

Send offprint requests to: J. Kreowski

© European Southern Observatory (ESO) 1999

Online publication: May 6, 1999

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