Ages of Galaxies Bulges and Disks From Optical and Near-Infrared Colors

Peletier, R. F.; Balcells, M.
Referencia bibliográfica

Astronomical Journal v.111, p.2238

Fecha de publicación:
6
1996
Número de autores
2
Número de autores del IAC
0
Número de citas
183
Número de citas referidas
154
Descripción
We compare optical and near-infrared colors of disks and bulges in a diameter-limited sample of inclined, bright, nearby, early-type spirals. Color profiles along wedge apertures at 15^deg^ from the major axis and on the minor axis on the side of the galaxy opposite to the dust lane are used to assign nominal colors for the inner disks (at 2 scale length) and for the bulges (~0.5r_eff_), respectively. We estimate that the effects of dust reddening and the cross-talk between the colors of the two components is negligible. We find that color differences (bulge-disk) are very small: {DELTA}(U-R) = 0.126+/-0.165, {DELTA}(R-K)=0078+/-0.165. Disks tend to be bluer by an amount three times smaller than that reported by Bothun & Gregg [ApJ, 350,73(1990)] for S0s. Color variations from galaxy to galaxy are much larger than color differences between disk and bulge in each galaxy. Probably, the underlying old population of disks and bulges is much more similar than the population paradigm would lead us to believe. Implied age differences, assuming identical metallicities, are less than 30%.