1999/03/23 by T. Bremnes, B. Binggeli, P. Prugniel · 7 citations
Environmental Science · Physics and Astronomy · #Astronomy and Astrophysical Research #Galaxies: Formation, Evolution, Phenomena #Impact of Light on Environment and Health #astro-ph
paper · pdf · doi:10.1051/aas:1999486
15 pages, 4 tables and 13 figures. For a full resolution version see http://www.astro.unibas.ch/galaxies/papers.html To appear in A&AS
arxiv created 1999/03/23 · openalex publication_date 1999/06/01 · arxiv updated 2009/12/01 · openalex created_date 2022/10/04 · openalex updated_date 2026/07/31
We have carried out CCD photometry in the Cousins B and R bands of 21 dwarf galaxies in and around the M101 group. Eleven are members and suspected members of the group and ten are field galaxies in the projected vicinity of the group. We have derived total magnitudes, effective radii, effective surface brightnesses, as well as galaxy diameters at various isophotal levels in both colours. Best-fitting exponential parameters and colour gradients are also given for these galaxies. Some of the galaxies show a pronounced luminosity excess above the best-fitting exponential at large radii, or surface brightnesses fainter than in R. This feature, while non-significant for a single case and technically difficult to interpret, might be an indication of the existence of an extended old stellar halo in dwarf irregulars. The photometric parameters of the galaxies presented here will be combined with previously published data for nearby dwarf galaxies and statistically analysed in a forthcoming paper.