The following contribution was included in the
1993 Annual Report of the Kapteyn Astronomical Institute
of the Rijksuniversiteit Groningen, p. 33

Measurements of dust extinction in highly inclined galaxies

R.A. Jansen, J.H. Knapen, J.E. Beckman (I.A.C., La Laguna, Tenerife), R.F. Peletier and R. Hes have studied the extinction properties of dust in the well-defined dust lanes of four highly inclined galaxies using U, B, V, R and I band CCD and J and K' band Near-Infrared array images. For three of these galaxies, they have used the symmetry of the underlying light profile to obtain absolute extinction values in the dust lanes. Maximum values for the dust extinction near the centre of the galaxies range between 2 and 3 magnitudes in B.
They have studied the extinction law in these three galaxies by investigating the extinction ratios A\lambda / AV . Assuming that the dust is uniformly mixed with the stars they find good agreement with the extinction law in our Galaxy and in the Sombrero galaxy (NGC 4594). They can discard a model of a screen of dust, thus eliminating the possibility that the scale-length of the dust is larger than that of the stellar population. The measured extinction values decrease rapidly with radius when going outward.

Figure 1 Figure 2

Figure 1. (left)Minor axis extinction profiles over the dust lane in UGC 3065.
Figure 2. (right) Extinction ratios A\lambda / AV as a function of wavelength \lambda for the four galaxies, compared to the Galactic extinction law (from Rieke & Lebofsky) and that for the Sombrero galaxy (from Knapen et al.). Errors are typically 0.05 magnitude.

Book Reviews, Popular Articles

R.A. Jansen, ``De ware vorm van de Melkweg'', 1993, Zenit 20, 153 - 156

Participation in Scientific Meetings

R.A. Jansen, 48e Nederlandse Astronomen Conferentie (De Haan aan Zee, Oostende,
        Belgium, 6 - 7 May '93): ``Extinction by Dust in Highly Inclined Galaxies'' (poster paper)

Work Visits

R.A. Jansen, I.A.C. (La Laguna, Tenerife, Spain): 12 - 26 July '93

Popular Lectures

R.A. Jansen, ``Het Heelal op straat'' (14 - 15 October; Scholierenmanifestatie Nationale
        Wetenschapsweek, R.U.Groningen) (with W.J.G. de Blok, R.A. Swaters, P.A. Woudt,
        R. de Grijs, & J. Gerritsen)

Organization of the Astronomy Department

R.A. Jansen, Astronomy Education Committee   (student member, till 1-09-'93)

Last updated: Nov 15, 2000 (minor style change)