| Popis: |
Gas-phase (including ions and molecules) interstellar measurements of some elements can place tight constraints on their Galactic, or at least their total (gas+dust) local interstellar abundances. The interstellar medium within 1500pc of the Sun seems to be well represented by a single standard reference abundance. Here we discuss the limits placed on that standard abundance by measurements of the elements O, C, N, Kr and Sn in the interstellar medium. These are the elements for which we have some idea of their dust-phase compositions. The abundance of Kr in the local (out to 1500 pc) interstellar medium is subsolar at about 60% of the meteoritic value as compared to H. Oxygen in the same regions appears to have solar abundances. Tin, a primarily s-process element, is supersolar in the local ISM, however we cannot determine to what extent. Nitrogen and carbon abundances are more difficult to ascertain, but they, like oxygen, appear to be solar within measurement errors. |
