DELLA VALLE, MassimoMassimoDELLA VALLEPanagia, NinoNinoPanagia2022-09-282022-09-2819920004-6256http://hdl.handle.net/20.500.12386/32657We 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 R_B_ = A_B_/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 <M_B_> = - 19.24+/-0.18(1σ) + 5 log(H_0_/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 {DELTA}[E(B-V)]=0.13+/-0.04 and a dispersion of extinction to SNe of σ[E(B-V)]=0.15+/-0.01. Allowing for extinction biases, the total width of the dust disk turns out to be 2τ_0_= 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.STAMPAenArticle10.1086/1162652-s2.0-0013003066https://api.elsevier.com/content/abstract/scopus_id/0013003066https://ui.adsabs.harvard.edu/abs/1992AJ....104..696D/abstract1992AJ....104..696DFIS/05 - ASTRONOMIA E ASTROFISICA