Carbon star survey of Local Group galaxies IX. The spheroidal galaxy NGC 185

We used the CFH12K wide field camera to survey the carbon star population of NGC 185 using the CN-TiO technique. 145 C stars are identified with a mean (I) = 19.99 +/- 0.05, corresponding to M-I) = -4.41 +/- 0.05, a mean luminosity similar to what was recently found for the C star population of NGC 147. The stellar surface density profile of NGC 185 follows a power law with an exponential scale length of 2.53 +/- 0.07'. The surface density of C stars follows also a power law but with a smaller scale length, 1.56 +/- 0.06, demonstrating that the intermediate-age population of NGC 185 is more concentrated than its old population. A tidal radius, r(t) = 22.5 +/- 2.2' is determined from red giant star counts. The C/M ratio of NGC 185 is 0.17 +/- 0.02 with no apparent sign of a radial gradient. We compare the carbon star populations of NGC 185 and NGC 147 to conclude that it is unlikely that they form a close pair.