Date Presented:
2011/07/1
Abstract:
We reexamined the total extinction along the sightline of a quasar (J004457+4123) behind the disk of M31 and used a varying total-to-selective extinction ratio in order to obtain a better agreement between its optical spectrum and a composite SDSS spectrum based on input spectra of quasars from DR7 at similar redshifts. The M31 outermost disk predominates (~85%) the total foreground (Milky Way+M31) selective extinction EB-V = 0.30+/-0.05 mag and the derived gas-to-dust ratio is N(H)/EB-V = (3.5+/-0.7)×10
20 atcm
-2 mag
-1.
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