Surface Photometry of Edge-on Galaxies. I. NGC 5866

Detailed surface photometry of the edge-on SO galaxy NGC 5866 was carried out in B and V color bands by a computerized digital method. The luminosity distribution was analyzed in the standard manner and then decomposed into the spheroid and the disk components. The main results are: (1) The luminosity profile along the minor axis (spheroid profile) is well represented by either the r^1/4-law or the Hubble law. (2) The reduced luminosity gradients of the spheroid, -3.54(B) and -3.51(V), are indistinguishable from those of elliptical galaxies. (3) The blue color of the ansae (handles), (B- V) ≲ 0^m.6, suggests the presence of a stellar population younger than that in the spheroid. (4) There is a hint of a color gradient, Δ(B-V)/Δr ∼ -O.34 mag arcmin^-1, along the minor axis. (5) Mean profiles except for that along the major axis are well reproduced by three-dimensional mass models for axisymmetric galaxies proposed by Miyamoto and Nagai (1975) and by Satoh (1980). (6) The intrinsic flattening of the spheroid is about 0.44, which corresponds to those of E5-6 galaxies. (7) The effect of the spheroid on B(0)_c value is dominant, relative to the disk, in the face-on luminosity profile derived on the basis of model analysis.