Fuse Observations of Capella
نویسندگان
چکیده
Far Ultraviolet Spectroscopic Explorer (FUSE ) observations of the bright binary system Capella (α Aurigae; G1 III + G8 III) reveal a rich emission line spectrum containing neutral and ionic species, among them H i, O i, C iii, Ovi, Svi, Nev and Nevi. In addition the Fexviii 974.85 Å line, formed at temperatures of ≈ 6 × 10 K, is detected. Whereas the chromospheric and transition region emission is dominated by that from the G1 giant, consistent with results from previous ultraviolet observations, Fexviii is formed largely in the G8 giant atmosphere. Line ratios from C iii suggest densities of 2– 8×10 cm, although anomalous line profiles of the λ1176 transition may signal optical depth effects. The hydrogen Lyman series, detected for the first time, displays asymmetric emission consistent with an expanding atmosphere. Subject headings: stars: chromospheres–stars: coronae–stars: individual (Alpha Aur)– stars: late-type–ultraviolet: stars
منابع مشابه
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