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Session 71 - Globular Clusters.
Display session, Wednesday, January 15
Photometric observations of the globular cluster systems of the two brightest elliptical galaxies in the Eridanus A sub-cluster, NGC 1400 and NGC 1407, have been obtained in the Washington T_1 and Kron-Cousins I filters. The M/L value for Eridanus A appears to be exceptionally high, previously estimated at \sim 3000h, suggesting that this cluster is highly dominated by dark matter. NGC 1400's radial velocity, 549 km/s, is extremely low compared to that of the central galaxy (NGC 1407, v_ødot=1766 km/s) and the other members of Eridanus A, implying that it is a foreground galaxy projected by chance onto the cluster. Using the observed shapes of the globular cluster luminosity functions, we obtain distances of 17.6 \pm 3.1 Mpc to NGC 1407 and 25.4 \pm 7.0 Mpc to NGC 1400, supporting earlier conclusions that NGC 1400 is at the distance of Eridanus A and therefore has a large peculiar velocity. We derive specific frequencies of S_N=4.0 \pm 1.3 and S_N = 5.2 \pm 2.0 for NGC 1407 and NGC 1400 respectively, using an adopted distance to the cluster of 20.5 \pm 1.2 Mpc based on the mean recessional velocity of the cluster members and H_0=80 km s^-1 Mpc^-1.
Program listing for Wednesday