On the relation between diffuse bands and column densities of H, CH and CO molecules ^*

¹ Kazimierz Wielki Academy, Faculty of Physics, Weyssenhoffa Sqr. 11, 85-072 Bydgoszcz, Poland e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
² Special Astrophysical Observatory, Nizhnij Arkhyz 357147, Russia e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
³ Isaac Newton Institute of Chile, SAO Branch e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
⁴ Center for Astronomy, Nicolaus Copernicus University, Gagarina 11, 87-100 Toruń, Poland e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Corresponding author: T. Weselak, This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 7 February 2003
Accepted: 11 September 2003

Abstract

Mutual relations between column densities of H₂, CH and CO molecules as well as between the latter and strengths of the major 5780 and 5797 diffuse bands are presented and discussed. The CH radical seems to be a good H₂ tracer, possibly better than CO. It is also demonstrated that the molecular fraction of the H₂ molecule is correlated with an intensity ratio of 5797 and 5780 DIBs, suggesting the possible formation of narrow DIB carriers in denser clouds, dominated by molecular hydrogen and reasonably shielded from ionizing UV radiation by small dust grains.