ABSORPTION LINE GRADIENTS IN THE SPECTRUM OF AN ELLIPTICAL GALAXY NGC 5864A

Abstract

The archival long-slit spectra, covering the wavelength range 4050 ~ 5150 Å, have been used to investigate the radial behavior of absorption line fea-tures (G4300, Fe4383, Ca4455, Fe4531, and Hβ) of an elliptical galaxy NGC 5846A. The heliocentric recession velocity of NGC 5846 has been derived as 1949±87 km/s. Fe absorption lines of NGC 5846A show significant radial gradients with the mean slope of ∆/∆(r")=-0.863±0.202. There is also a significant radial gradient of G band with a slope of -1.109±0.098. On the other hand, no radial gradients has been detected on the Ca4455 and Hβ absorptions of NGC 5846A. A metallicity gradient, which is derived from the Fe line gradients, is similar to the abundance gradient predicted by Larson's (1975) dissipative models for the formation of elliptical galaxies. We also note that a galaxy-galaxy interaction could affect the line gradients of NGC 5864A.