Interstellar Extinction and Elemental Abundances

Elements in the interstellar medium (ISM) exist form of gas or dust. The extinction and elemental abundances provide crucial constraints on composition, size, quantity Most modeling efforts have assumed total (gas dust) dust-forming elements—known as "interstellar abundances," reference "cosmic abundances"—to be solar gas-phase to environmentally independent. However, it remains unclear whether are an appropriate representation abundances. Meanwhile, known exhibit appreciable variations with local environments. Here we explore viability B stars, protosolar abundances, augmented by Galactic chemical enrichment (GCE) quantitatively examining 10 sight lines for which both curves all major elements (i.e., C, O, Mg, Si Fe) been observationally determined. Instead assuming a specific dust model then fitting observed curves, each line apply model-independent Kramers–Kronig relation, relates wavelength-integrated volume, place lower limit depletion. This, together derived allows us rule out B-star, solar, standard support GCE-augmented viable