On the triaxiality of elliptical galaxies

Abstract

Ellipticities and position angles are presented as functions of the major axis radius for 32 nearby elliptical galaxies from images obtained with a CCD camera. Comparisons with other observers and with multiple observations of some of the galaxies with a different camera configuration establish the reliability of the measurements. Ellipticity, ellipticity gradient, and position angle gradient are tabulated for each galaxy and statistically compared to projections of triaxial, coaxial, and concentric spheroids whose ellipticities vary with radius. The data are consistent with the galaxies all being triaxial with substantial ellipticity gradients and inconsistent with their all being coaxial, concentric, and axially symmetric.