X-ray absorption, interstellar reddening, and elemental abundances in the interstellar medium

Abstract

X-ray absorption and interstellar reddening along the line of sight to five supernova remnants are shown to yield the relationship NxIE3 -v = (6.8 j 1.6) x 1021 equivalent H atoms mag . It is also shown that within 1 to 5 kpc of the Sun, the "universal" abundances hold in the interstellar medium. The quoted value of the ratio NxIEB - v may also apply to the galactic center X-ray source; N and EB - V individually are high, probably due to the presence of a large column of molecular hydrogen andlor an abundance gradient of metals (mainly C, N, 0) in the Galaxy. Subject headings: abundances - interstellar matter - supernova remnants - X-ray sources