Calibration of the Fundamental Plane Zero Point in the Leo I Group and an Estimate of the Hubble Constant

Abstract

We derive new effective radii and total magnitudes for 5 E and S0 galaxies in the Leo-I group from wide-field 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 find 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 find 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

The Globular Cluster Systems in the Coma Ellipticals. I. The Luminosity Function in NGC 4874 and Implications for Hubble’s Constant

“…However, our determination of 4.06 is similar to other, more recent determinations that rely directly on the giant ellipticals : for example, SBF analysis of ellipticals in Coma and Leo I (Thomsen et al 1997) and the fundamental plane comparison for the Leo and Coma ellipticals (Hjorth & Tanvir 1997) give *k(Coma [ Leo)^4.8È4.9. Subtracting *k(Virgo [ Leo) \ 0.87^0.1 (Ferrarese et al 2000a) then gives *k^4.0 to 4.1 for the Virgo-to-Coma step, in agreement with our Ðndings.…”

COMPTEL upper limits for the $^{\sf 56}$Coγ-ray emission from SN1998bu

“…The host galaxy M 96 had a HST-Cepheid-determined distance of 11.6 ± 0.9 Mpc (Tanvir et al 1995), later revised to 11.3 ± 0.9 Mpc by Hjorth & Tanvir (1997). This makes SN1998bu one of seven SN observed in galaxies with a distance set by Cepheid measurements.…”

“…TJD 10 935 ± 1). The distance to M 96 had been known from HST Cepheid measurements as 11.3 ± 0.9 Mpc (Hjorth & Tanvir 1997), though another value of 9.6 ± 0.6 Mpc had been derived from measurements of planetary nebulae (Feldmeier et al 1997). SN1998bu appears to be a typical type Ia event (Jah et al 1999), its reddening can be attributed to dust in the host galaxy.…”

Unified One‐Dimensional Simulations of Gamma‐Ray Line Emission from Type Ia Supernovae

“…Distance estimates have ranged from 9:6 AE 0:6 Mpc from planetary nebulae (Feldmeier et al 1997) to 11:6 AE 0:9 Mpc from Hubble Space Telescope (HST ) Cepheid period luminosity estimates (Tanvir et al 1995). Subsequent HST Cepheid period luminosity estimates place M96 at 9.9-11.3 Mpc (Gibson & Stetson 2001;Gibson et al 2000;Hjorth & Tanvir 1997), the range we use in this study. The CGRO team was able to begin observations at about maximum light.…”