Statistical connections between the properties of Type Ia supernovae ( SNe Ia ) and the B–V colors of their parent galaxies are established .
Compared to SNe Ia in blue galaxies [ ( B - V ) _ { T } ^ { o } \la 0.75 ] , SNe Ia in redder galaxies have ( 1 ) a wider dispersion in the blueshifts of their Si II \lambda 6355 absorption features , ten days after maximum light ; ( 2 ) more rapidly declining light curves ; and ( 3 ) lower luminosities .
Even when the spectroscopically peculiar , very subluminous SNe Ia such as SN 1991bg are disregarded , SNe Ia in red galaxies are less luminous than those in blue galaxies by about 0.3 magnitudes .

When SNe Ia that are thought to have been significantly extinguished by dust in their parent galaxies are disregarded , those in blue galaxies have observational absolute–magnitude dispersions of only \sigma _ { obs } ( M _ { B } ) =0.20 and \sigma _ { obs } ( M _ { V } ) =0.17 , which implies that their intrinsic absolute–magnitude dispersions are very small .
We use six SNe Ia whose absolute magnitudes have been calibrated by means of Cepheids , which also indicate that the intrinsic absolute–magnitude dispersions of SNe Ia in blue galaxies are very small , to calibrate SNe Ia in blue galaxies and obtain H _ { 0 } = 57 \pm 4 km s ^ { -1 } Mpc ^ { -1 } .
This value is in excellent agreement with that obtained by Saha et al .
( 1995b ) , in spite of the fact that they do not take into account any dependence of SN Ia absolute magnitude on the nature of the parent galaxy .

Some implications of the statistical connections between SNe Ia and the colors of their parent galaxies , for identifying the progenitor binary systems of SNe Ia and for using high–redshift SNe Ia to measure q _ { 0 } , are briefly discussed .