Energy Distributions, K Corrections, and the Stebbins-Whitford Effect for Giant Elliptical Galaxies

The energy d~istribution F(X) in the range 3350 A «= X «= 5850 A has been measured with a spectral resolution of 50 A for a number of nearby giant E and SO galaxies and for M31 and M32. The distribution in the near-infrared to X = 10800 A has been obtained for NGC 3379 and NGC 4472. The various distributions, apart from that for M32, are nearly identical and have been averaged to obtain a standard F(X) from which new KB, K~, and KR corrections for the effects of redshifts are calculated, as listed in Table 4. New observations of B - V colors for the several brightest galaxies in thirty-one clusters, covering the redshift range 0 <z «= 0.20, are listed in Table 6. Figure 2 shows the observed color change with redshift. Agreement of the observations with the predicted color change, KB - K~, shows, following an earlier result by Whitford, that the Stebbins-Whitford effect is absent to the 3 per cent level in the broad-band B - V system and that no variation of the shape of F(X) with time is present larger than that implied by z~(B - V) «= 0 03 mag for redshifts as large as z = 0 20 The shape change of F(X) because of evolution of the stellar content in the lookback time must, therefore, be below the limit of present detectability