Surface brightness measurements of
extended galactic nebulae

Ronald Stark
Klaus Reif

Max-Planck-Institut fÓÌr Radioastronomie, Auf dem HÓÌgel 69, D-53121 Bonn, Germany
stark@mpifr-bonn.mpg.de
Sternwarte, UniversitÓ?t Bonn, Auf dem HÓÌgel 71, D-53121 Bonn, Germany
reif@astro.uni-bonn.de

Abstract:

We discuss the importance of digitised sky-limited Schmidt B- and R-band, and H images of extended translucent ( mag) and dark ( mag) clouds. In translucent clouds (e.g. high-latitude cirrus) photons can penetrate through the whole cloud and control the physical and chemical processes. Comparison of the B images with far-infrared/submillimetre CO, [CÒš], and [CÒš] emission provides important information on the non-homogeneous cloud structure, carbon chemistry, and energy balance. In dark clouds the interior is completely shielded from the interstellar radiation field. L1204 is a dark cloud with at its edge the well-known HÒš rim S140. The R-band image shows S140 as well as the diffuse extended HÒš region around the exciting B-type star. However, the sensitivity for H in the R-band is rather low and there is contamination with diffusely scattered red light from dust. Deep H and R-band imaging of an field has recently been done with the 1m Hoher List telescope of Bonn University. A wealth of small-scale structures can been seen on continuum subtracted images which provide new insight on the geometry of this cloud.

Keywords: ISM: clouds, dust, individual (cirrus, S140/L1204), reflection nebulae, structure

Ò? Copyright Astronomical Society of Australia 1997