Calibration of the fundamental plane zero - point in the Leo - Igroup and an estimate

نویسندگان

  • Jens Hjorth
  • Nial R. Tanvir
چکیده

We derive new eeective radii and total magnitudes for 5 E and S0 galaxies in the Leo-I group from wide-eld CCD images. These are used in conjunction with recent literature velocity data to construct the fundamental plane (FP) of the Leo-I group. The rms scatter that we nd is only 6 % in distance. The zero point of this relation provides a calibration of the FP as a distance indicator and directly determines the angular diameter distance ratio between the Leo-I group and more distant clusters. In the language of Jerjen and Tammann (1993) we determine a cosmic velocity of the Leo-I group of 757 68 km s ?1 relative to the Coma cluster, or 796 57 km s ?1 relative to a frame of 9 clusters. Combining this velocity with the Cepheid distance to M96, a member of Leo-I, we nd the Hubble constant to be H 0 = 67 8 km s ?1 Mpc ?1 or H 0 = 70 7 km s ?1 Mpc ?1 for each case. The distance we obtain for the Coma cluster itself (108 12 Mpc) is in good agreement with a number of other recent estimates. 1 Based on observations made with INT operated on the island of La Palma by the Royal Greenwich Observatory in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof sica de Canarias.

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Calibration of the fundamental plane zero-point in the Leo-I group and an estimate of the Hubble constant

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تاریخ انتشار 1997