Steps toward the Hubble constant. VII. Distances to NGC 2403, M101, and the Virgo cluster using 21 centimeter line widths compared with optical methods: The global value of H/sub 0/
The discovery by Tully and Fisher that absolute B magnitudes of galaxies and their 21 cm line widths (corrected to edge-on orientation) are very tightly correlated has opened the way to test the previously determined distances to the M81-NGC 2403 and the M101 groups.The recalibration of the Tully-Fisher relation gives M/sub pg//sup 0//sup ,//sub i/=-6.88..delta..v/sub 21//sub i/-2.36 based on a Hyades modulus of 3.03 mag. Application to the nearby groups gives 21 cm radio moduli of (m-M)/sub 0/=27.64 +- 0.09 for M81-NGC 2403, and 29.08 +- 0.16 for M101, based on adopted distances to M31, M33, and the Hyades alone. Comparison with the previous optical values of (m-M)/sub 0/=27.55 +- 0.13 and 29.30 +- 0.3 provides support for the present local distance scale.Application of the 21 cm method to 19 spirals within the central 6degree (radius) of the Virgo cluster gives (m-M)/sub 0/=31.4 +- 0.2 for distance modulus to the cluster. Data from six optical methods give (m-M)/sub 0/=31.50 +- 0.08 for the Virgo cluster. The agreement with the 21 cm method again provides a satisfactory test of the current distance scale.Adopting a revised Hyades modulus of (m-M)/sub 0/=3.23 gives a weighted mean Virgo modulus of (m-M)/sub 0/=31.70 +- 0.08(D=21.9 1(- 0.9 Mpc). This modulus provides absolute magnitude calibration of first-ranked cluster E galaxies, and calibration of the ridge-line of the velocity-magnitude relation for great clusters. The resulting global value of the Hubble constant is H/sub 0/=50.3 +- 4.3sigmakm s/sup -1/ Mpc/sup -1/, which gives H/sub 0//sup -1/= (19.4 +- 1.6) x 10/sup 9/ years.
- Research Organization:
- Hale Observatories, Carnegie Institution of Washington, California Institute of Technology
- OSTI ID:
- 7240226
- Journal Information:
- Astrophys. J.; (United States), Vol. 210:1
- Country of Publication:
- United States
- Language:
- English
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