NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-03-21 T02:56:42 PDT
Help | Comment | NED Home

For refcode 1994A&AS..104..179G:
Retrieve 56 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by European Southern Observatory (ESO). Reproduced by permission
1994A&AS..104..179G Interstellar matter in Shapley-Ames elliptical galaxies. I. Multicolour CCD surface photometry P. Goudfrooij, L. Hansen, H.E. Jorgensen, K.U. Norgaard-Nielsen, T. de Jong and L.B. van den Hoek Astronomical Institute "Anton Pannekoek", University of Amsterdam, Kruislaan 403, NL1098 53 Amsterdam, The Netherlands Copenhagen University Observatory, Oster Voldgade 3, DK-1350 Kobenhavn K, Denmark Danish Space Research Institute, Gl. Lundtoftevej 7, DK-2800 Lyngby, Denmark Laboratory for Space Research, P.O. Box 800, NL-9700 AV Groningen, The Netherlands Received June 30; accepted August 13, 1993 Abstract. - We present accurate CCD surface photometry in Johnson B and V and Cousins I for a complete, magnitude-limited sample of 56 elliptical galaxies from the RSA catalog. For each galaxy we have determined radial profiles of surface brightness, B - V and/or B - I colour index, ellipticity, position angle, and the third- and fourth order Fourier coefficients that describe the deviations of the B, V, and I isophotes from perfect ellipses, using a full two-dimensional fitting technique. The present sample contains 13 galaxies for which no previous isophote analysis has been published, and 26 without published colour gradients. The radial profiles of the ellipticity, position angle, and the third- and fourth-order Fourier coefficients are found to show considerable detail. The profiles are mostly similar in all passbands, except in cases where dust lanes or patches are present. In this respect, the higher- order Fourier coefficients turn out to be sensitive diagnostic tools for the presence of dust in elliptical galaxies. Isophotal deviations from ellipses on the level of 0.5-1% are found to be common in elliptical galaxies. As noted before by others, these deviations are due to structures that do not necessarily align with the apparent major or minor axes of the galaxies, advocating the use of both the cosine and sine higher-order terms in correlation studies. We show that fitting outer radial intensity profiles of elliptical galaxies is an excellent tool for determining the sky background for the surface photometry. The sky values determined from a power-law fit to the outer intensity profiles are found to be within 0.1% of the sky values at the corners of present-day large CCDs where the contribution of galaxy light is negligible. The average colour gradients for the sample galaxies in B -V and B - I are 0.06 and 0.14 mag arcsec^-2^ per decade in radius, respectively. This compares well with colour gradients in elliptical galaxies found by others. The small uncertainty introduced by the sky background determination method applied here results in an average internal uncertainty of only ~0.01 mag for our colour gradients, which is significantly better than the results of previous studies. The profiles are compared extensively with results from other authors when available. The result is encouraging, especially for the ellipticity and position angle where we find mean RMS differences of 0.01 and 1.8^deg^, respectively. The surface brightness profiles generally agree to within +/-0.05^m^. Key words: galaxies: elliptical - galaxies: fundamental parameters - galaxies: photometry
Retrieve 56 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home