This picture is proof of interstellar gas and dust clouds between this star and us,  a narrow absorption line of Ca II in the spectrum of epsilon Orionis, a B0 supergiant.  A B0 star is to hot to have Ca II absorption feature, so the Ca II absorption spectrums must be from several different interstellar gas and dust clouds between us and the star.  Each of the interstellar dust clouds is moving with respect to the star, epsilon Orionis, and us a different velocities.