Near-infrared and optical broadband surface photometry of 86 face-on disk dominated galaxies. II. A two-dimensional method to determine bulge and disk parameters*
Kapteyn Astronomical Institute, P.O. Box 800, NL-9700 AV Groningen, The Netherlands
Corresponding author: Send offprint request to: R.S. de Jong, University of Durham, Dept. of Physics, South Road, Durham, DH1 3LE, UK, e-mail: R.S.deJong@Durham.ac.uk
Accepted: 9 October 1995
In this Paper I present a new two-dimensional decomposition technique, which models the surface photometry of a galaxy with an exponential light profile for both bulge and disk and, when necessary, with a Freeman bar. The new technique was tested for systematic errors on both artificial and real data and compared with widely used one-dimensional decomposition techniques, where the luminosity profile of the galaxy is used. The comparisons indicate that a decomposition of the two-dimensional image of the galaxy with an exponential light profile for both bulge and disk yields the most reproducible and representative bulge and disk parameters. An extensive error analysis was made to determine the reliability of the model parameters. If the model with an exponential bulge profile is a reasonable description of a galaxy, the maximum errors in the derived model parameters are of order 20%. The uncertainties in the model parameters will increase, if the exponential bulge function is replaced by other often used bulge functions as the de Vaucouleurs law. All decomposition methods were applied to the optical and near-infrared data set presented by de Jong & van der Kruit (1994), which comprises 86 galaxies in six passbands.
Key words: methods: data analysis / surveys / galaxies: fundamental parameters / galaxies: photometry / galaxies: spiral / galaxies: structure
Based on observations with the Jacobus Kapteyn Telescope operated by the Royal Greenwich Observatory at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias with financial support from the PPARC (UK) and NWO (NL) and with the UK Infrared Telescope at Mauna Kea operated by the Royal Observatory Edinburgh with financial support of the PPARC
© European Southern Observatory (ESO), 1996