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We have collected and analyzed the color excess data for the best photometrically studied type Ia supernovae (SNIa) which occurred in late type galaxies. From these data we find a ratio of the B band to selective extinction in the parent galaxies of RB_ = AB_/E (B-V) =3. 35+/-0. 25 (1σ). This indicates that the extinction curves in latetype galaxies have similar properties to that of our Galaxy. We obtain a new calibration for the absolute magnitude at maximum of SNIa in late type galaxies = - 19. 24+/-0. 18 (1σ) + 5 log (H₀_/75), which is marginally brighter than the recent determinations for type Ia supernovae observed in elliptical (dust-free) galaxies, and appears to confirm the potential of SNIa as standard candles for distance determinations. Studying the distribution of the extinction in the parent galaxies we find an average half-width of selective extinction of DELTAE (B-V) =0. 13+/-0. 04 and a dispersion of extinction to SNe of σE (B-V) =0. 15+/-0. 01. Allowing for extinction biases, the total width of the dust disk turns out to be 2τ₀_= 1. 28+/-0. 23 mag. These results imply that SNIa have a considerably broader distribution than the dust disk and confirm that they are older than old disk population objects, i. e. , age > 1-2 billion years. Also, we conclude that total extinction thickness of late type galaxies is very similar to that of the Milky Way.
Valle et al. (Sat,) studied this question.